HIERDIE EKSEMPlAAR MAG ONDER UOVS - SASOL-BIBLIOTEEK
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BIBLIOTEEK VERWYDER \VORD NIE I~~~I~~~~~~I~~~I~I~~~~~~199800464301220100013
VEGETATION ECOLOGY OF THE SOUTHERN FREE STATE
by
PIETER WILLEM MALAN
Submitted in fulfilment of the requirements
for the degree
PHILOSOPHIAE DOCTOR (BOTANY)
in the Faculty of Science
(Department of Botany & Genetics)
University of the Orange Free State
Bloemfontein
November 1997
Promotor: Prof. Dr. H.J.T. Venter
Co-promotor: Dr. P.J. du Preez
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I can do all things through Christ which strengthens me
- Philippians4: 13
I dedicate this dissertation to my parents.
i
ABSTRACT
VEGETATION ECOLOGY OF THE SOUTHERN FREE STATE
by
PIETERWILLEM MALAN
Promotor: Prof. Dr. H.J.T. Venter
Co-promotor: Dr. P.J. du Preez
Department of Botany & Genetics
University of the Orange Free State
PHILOSOPHIAEDOCTOR (BOTANY)
A detailed phytosociological investigation of the southern Free State was
conducted as part of the Grassland Biome Project which aims at a detailed
synecological and syntaxonomical synthesis of the Biome. The main purpose
of this study was to identify, classify, describe and ecologically interpret the
different vegetation types in the southern Free State. Braun-Blanquet
procedures and multivariate analysis were used in this study. A
phytosociological classification and synecological synthesis of the
vegetation of the southern Free State is presented. A DCA (DECORANA)
ordination was also applied to the floristic data set in order to determine
environmental attributes. This data should be used for future land-use
planning, management, research and conservation of the natural recourses
of the southern Free State.
CONTENTS
1.Introductory Background 1
1.1 Introduction 2
1.2 Aims 2
1.3 Methods 3
1.4 Distribution, number and size of sample plots .4
1.5 Floristic Analysis 5
1.6 Habitat Analysis 6
1.7 Thesis exposition 6
1.8 References 8
2. Physical environment and major plant communities of the southern Free State 16
2.1 Introduction 17
2.2 Study Area 18
2.2.1 Biomes in the southern Free State 18
2.2.1.1 Grassland Biome 19
2.2.1.1.a Vegetation 20
2.2.1.2 Nama-Karoo Biome 21
2.2.1.2.a Vegetation 22
2.2.2 Veld Types 22
2.2.2.1 Veld Type 51: Orange River Nama-Karoo 23
2.2.2.2 Veld Type 50: UpperNama-Karoo : 23
2.2.2.3 Veld Type 32: Kimberley Thorn Bushveld 23
2.2.2.4 Veld Type 52: Eastern Mixed Nama-Karoo .24
2.2.2.5 Veld Type 37: Dry Sandy Highveld Grassland 24
2.2.2.6 Veld Type 39.:Moist Cool Highveld Grassland 25
2.2.2.7 Veld Type 40: Moist Cold Highveld Grassland 25
Il
2.2.3 Geology 25
2.2.3.1 The Beaufort Group 26
2.2.3.1.aThe Adelaide Subgroup 26
2.2.3.1.b The Tarkastad Formation 26
2.2.3.2 The Ecca Group 27
2.2.3.2.a The Tierberg Shale Formation 27
2.2.3.3 The Stormberg Group 27
2.2.3.3.a The Molteno Formation 27
2.2.3.3.b The Elliot Formation 28
2.2.3.3.c The Clarence Formation 28
2.2.3.4 Alluvium, Sand and Calcrete · 28
2.2.3.5 Karoo Dolerite 29
2.2.4 Physiography ·· ··························.·2·9··
2.2.5 Ridges, Koppies and Mountains 30
2.2.6 Soils and Land Types 30
2.2.6.1 Soils 30
2.2.6.2 Land Types 32
2.2.6.2.1 ALand Type : 33
2.2.6.2.2 C Land Type , 33
2.2.6.2.3 D Land Type 34
2.2.6.2.4 E Land Type : 35
2.2.6.2.5 F Land Type , 36
2.2.6.2.6 I Land Type 36
2.2.7 Climate 37
2.2.7.1 Precipitation ··················7·3
2.2.7.2 Temperature 38
1ll
2.2.7.3 Climate Diagrams 38
2.3 Methods ; ··.· ···· ······.·.···· 39
2.4 Results and Discussion 39
2.5 Concluding Remarks ··..· ··· .49
2.6 References 51
3. Vegetation ecology of the southern Free State: Plant communities of the
Zastron area ·······································5··9·····
3.1 Introduction ·····..·.·······.·.·..···········..······ ·······.·60
3.2 Study area 61
3.3 Methods : 62
3.4 Results and discussion , , 63
3.5 References 82
4. Vegetation ecology of the southern Free State: Dry shrubland communities
of the rocky outcrops : ····..····..·..········.·.··..·····..·86
4.1 Introduction : 88
4.2 Study area : 88
4.3 Methods 89
4.4 Results and discussion..; ···..·····..·..·..·· ·· ·······9·0
4.5 References 122
5. Acacia communities and related shrub communities of the dry south-western
Free State 125
5.1 Introduction 126
5.2 Study area 127
5.3 Methods · · ··..······.·.···..··· ·······128
5.4 Results and discussion - 128
5.5 References 146
iv
6. Vegetation ecology of the southern Free State:
Riparian shrub communities ·..·····································.·1·5··0··
6.1 Introduction ··································.1··5·1··
6.2 Study area 153
6.3 Methods · 154
6.4 Results and discussion · ······································1·5··4···
6.5 References 166
7. Phytosociology of the southern Free State:
Overgrazed and retrogressed vegetation · ····························.1··7·0·
7. 1 Introduction : ·..·······································1··7·1····
7.2 Stratification ····..········.·.·..··············.·.· · 175
7.3 Study area 175
7.4 Methods · 176
7.5 Results and discussion ·..········································1··7·7····
7.6 References ' 196
8. Vegetation ecology of the southern Free State: Grassland. communities 204
8.1 Introduction , 205
8.2 Studyarea · ···..······ 208
8.3 Methods ·..····..····· · 209
8.4 Results and discussion . · 209
8.5 References 233
9. Phytosociology of the southern Free State: The wetlands · ·239
v
9.1 Introduction 240
9.2 Study area 241
9.3 Methods - 242
9.4 Results and discussion .243
9.5 References .259
10. Phytosociology of the southern Free State:
Pan vegetation of the dry south-western Free State 263
10.1 Introduction 264
10.2 Study area ,. 267
10.3 Methods · ·.··..·..······..··..·..··..·..··..···.268
10.4 Results and discussion 268
10.5 References 276
Il. Vegetation classes of the southern Free State 279
11.1 Introduction ·.·..···· ·····..···.280
11.2 Methods ~ : 281
11.3 Results and discussion ·..····..·..·······.·.··283
11.4 References 321
12 A floristic analysis of the plant species present in the entire dataset of the
southern Free State · 330
13 General discussion and concluding rernarks 368
13.1 General discussion.. 369
13.2 Concluding remarks · 372
13.3 References 374
vi
Opsomming 376
Summary 378
Acknowledgements 3 80
References 382
1
CHAPTER 1
Vegetation ecology of the southern Free State
Introductory Background
2
CHAPTER 1
INTRODUCTORY BACKGROUND
1.1 INTRODUCTION
Since the large scale classification of vegetation by Acocks (1953, 1988),
much progress has been made towards more detailed classifications, but a
detailed description of the vegetation of the southern Free State does not
exist yet. In view of the fast degradation of the vegetation in the southern
Free State and because of widespread ploughing of arable land, together
with livestock grazing pressure, it has become necessary that planning,
management and conservation strategies should become based on sound
ecological principles.
To enable optimal resource utilization and conservation, a vegetation
classification programme has been implemented in the Grassland Biome
(Mentis & Huntley 1982; Scheepers 1987). Figure 1.1 shows the position of
the study area in relation to the Grassland Biome. A detailed
phytosociological classification and synecological study of the vegetation of
the southern Free State for management and conservation purposes is
therefore long overdue. This study thus also forms an integral part of the
long-term aim to compile a synecological and syntaxonomical synthesis of
the Grassland Biome of southern Africa (Scheepers 1987).
1.2 AIMS
The aims of this study are: .
(1) To identify, classify, describe and ecologically interpret the different
. plant communities of the southern Free State,
(2) to compile a synecological synthesis of the southern Free State, and
(3) to concur with the goals of the Grassland Biome Project namely to
identify, describe and determine the location of major vegetation types
within the Grassland Biome (Mentis & Huntley 1982).
3
1.3 METHODS
The methods used during this study were, to a certain extent, dictated by
the availability of natural vegetation in this predominantly over-exploited
area. Large areas were found to be severely degraded due to inappropriate
agricultural land use. Extensive farming is by far the main form of land use
in South Africa (Tomlinson 1970, Edwards 1972, Edwards & Werger 1972,
Werger 1980). According to Werger (1980) it is generally accepted that
mismanagement of' veld through overstocking, trampling and incorrect
grazing systems are the main reasons for this situation.
The floristic-sociological (Zurich-Montpellier) approach or Braun-Blanquet
method (Braun-Blanquet 1932, 1964; Poore 1955 a, b, c; 1956; Becking
1957; Pawlowski 1966; Shimwell 1971; Werger 1974; Mueller-Dombois &
Ellenberg 1974; Whittaker 1978; Kent & Coker 1996) was used in this
study.
The purpose of the methodology of Braun-Blanquet is to construct a
global classification of plant communities (Kent & Coker 1996). Werger
(1973) stated that this method satisfies the three basic essential
requirements of a vegetation ecological study, namely: (i) it is scientifically
sound, (ii) it fuifiIIs the necessity of classification at an appropriate level, and
(iii) it is the most efficient and versatile amongst comparable approaches.
The approach is, however, not without 'its problems. Egler (1954) presented
one of the most eloquent criticisms, claiming that the method was over-
simplified and represented the forcing of a weak methodology onto a much
more complex real world. A major reason for Egler's comments was that he
was a follower of the Gleasonian individualistic view of the plant
community. He himself, however, admitted that much valuable work had
been completed by Braun-Blanquet and his colleagues in Europe (Kent &
Coker 1,996).
Since the introduetton of this method to South African phytosociologists
it was successfully applied in the Grassland Biome by Coetzee (1974),
Bredenkamp (1975), Scheepers (1975), Jarman (1977), Bredenkamp &
~----------------------------------~-------------------------------_. --
4
Theron (1978, 1980), Du Preez (1979), Potgieter (1982), Rossouw (1983),
Bosch et al. (1986), Du Preez (1986), Muller (1986), Van Wyk &
Bredenkamp (1986), Behr & Bredenkamp (1988), Bezuidenhout (1988),
Bredenkamp et al. (1989), Turner (1989), Bezuidenhout & Bredenkamp
(1990), Bredenkamp & Bezuidenhout (1990), Du Preez-& Venter (1990 a &
b), Kooij (1990), Kooij et al. (1990 a, b, c & d), Bezuidenhout &
Bredenkamp (1991 a & b), Breytenbach (1991), Du Preez (1991), Du Preez
& Bredenkamp (1991 a & b), Du Preez et al. (1991), Kooij et al. (1991,
1992), Matthews (1991), Malan (1992), Bezuidenhout (1993), Coetzee
(1993), Eckhardt (1993), Fuls (1993), Myburgh (1993) and many others. In
the Nama-Karoo Biome Werger (1973), Palmer (1989) and Smitheman &
Perry (1990) also applied this method.
Since a mass of field data was collected during this study, and
augmented by data from previous studies in the southern Free State, it
became necessary to consolidate and incorporate data of relevant plant
communities into a comprehensive and suitable data-base. It is difficult and
impractical to handle phytosociological tables of this dimension by standard
Braun-Blanquet procedures, especially where syntaxa are characterized by
different species or specific combinations of species or species groups. The
objective demarcation of data into various classes based on numerical
classification methods alone is ineffective, mainly due to the heterogeneity
of the data and also because of the presence of many species with limited
occurrences in the total data set (Du Preez 1991). A proposed procedure for
the analysis of large phytosociological data sets in the classification of
South African grasslands was recently published by Bredenkamp &
Bezuidenhout (1995). This technique was used to compile a synoptic table
from 2 370 relevés, representing 394 plant communities ..
1.4 DISTRIBUTION, NUMBER AND SIZE OF SAMPLE PLOTS
The sample plots in the study area were as far as possible, randomly
distributed in stratification units. The stratification was based firstly on land
types and secondly oh terrain units. Topographic maps ( scale - 1: 250 000)
were also used in order to better the stratification. In each sample plot total
L-- j
5
floristic composition, using the Braun-Blanquet cover-abundance scale
(Mueller-Dombois & Ellenberg 1974) was noted. Although land types were
used as a first stratification unit, these units were not seen as completely
separate vegetation units. Major ecosystems or vegetation types of
ecologically homogeneous areas were used as guidelines on a regional and
farm-level scale and represent a refinement of Acocks 's (1953, 1988) veld
type vegetation (Fuls 1993).
The total data set of this study consists of 2 370 relevés and more than
600 species.
Plot sizes were fixed on 16 m2 for grassland vegetation and 100 m2 for
woodland (shrubland), which is in accordance with Bredenkamp & Theron
(1978), Du Preez (1979), Van Wyk (1983), Malan (1992), Bezuidenhout
(1993) and Fuls (1993).
1.5 FLORISTIC ANAL VSIS
The floristic survey included a list of all the plant species present in a
sample plot. A cover-abundance value was estimated for each of these
species according to the Braun-Blanquet scale (Mueller-Dombois & Ellenberg
1974) which is as follows:
r - one or a few individuals (rare) with less than 1% cover of total sample
plot area;
+ - infrequent with less than 1% cover of total sample plot area;
1 - frequent with low cover, or infrequent, but with higher cover; 1%-5%
cover of total sample plot area;
2 - abundant with > 5%-25 % cover of total sample plot area, irrespective
of the number of individuals;
3 - > 25%-50% cover of total sample plot area, irrespective of the number
of individuals;
4 - > 50%-75 % cover of total sample plot area, irrespective of the number
of individuals;
6
5 - 75% cover of total sample plot area, irrespective of the number of
individuals.
Taxa names conform to those of Arnold & De Wet (1993).
1.6 HABITAT ANALYSIS
Bezuidenhout (1993) stated that the distribution of plant communities is
closely related to environmental conditions. Environmental data recorded
during this study include land type, geology, terrain unit, soil type and
depth, soil texture, aspect, slope, rockiness of the soil surface, erosion and
utilization by herbivores (Fuls 1993).
1.7 THESIS EXPOSITION
This dissertation is divided into two parts (Parts 1 & 2). Part 1 contains
detailed descriptions of the relevant vegetation groups in each chapter,
while Part 2 contains a" the relevant figures and tables used in this
dissertation. Part 2 should thus be seen as complementary to Part 1.
This study consists of a number of chapters a" of which are presented in
the form of (as yet) unpublished research papers.
Each chapter or unpublished research paper forms an entity in itself.
Although the references relevant to a specific chapter are listed at the end
of that chapter, a comprehensive list of references is presented at the back
of this dissertation.
This thesis reports on a number of detailed vegetation ecology surveys of
the major vegetation units of the southern Free State as identified in Chapter
2. Hiqrophvllous vegetation of the stream beds and wetlands identified as
vegetation" unit 4 is split into the wetland vegetation of the southern Free
State (Chapter 9) and pan vegetation of the dry south-western Free State
(Chapter 10). Chapter 2 also contains a detailed description of the study
7
area. For a detailed description of the relevant area studied in each chapter,
please refer to Chapter 2.
This dissertation also contains a comprehensive phytosociological
synthesis of the vegetation of the southern Free State which includes data
compiled by other researchers within the study area (Scheepers 1975, Du
Preez 1991, Kooij 1990, Eckhardt 1993, Fuls 1993).
8
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10
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I
_I
11
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12
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Pretoria.
PALMER, A.R. 1989. The vegetation of the Karoo Nature Reserve, Cape
Province. I. A phytosociological reconnaissance. S.Afr.J.80t. 55: 215-
230.
PAWLOWSKI, B. 1966. Review of terrestrial plant communities. A.
Composition and structure of plant communities and methods of their
study. In: Szafer, W. (ed.) The Vegetation of Poland. Pergamon
Press/PWN Polish Scientific Publishers, Warshaw: 241-281.
POORE,M.E.D. 1955 a. The use of phytosociological methods in ecological
investigations: The Braun-Blanquet system. J. Ecol. 43: 226-244.
POORE, M.E.D. 1955 b. The use of phytosociological methods in ecological
investigations: Practical issues involved in an attempt to apply the Braun-
Blanquet system. J. Ecol. 43: 245-269.
14
POORE, M.E.D. 1955 c. The use of phytosociological methods in ecological
investigations: Practical implications. J. Ecol. 43: 606-651.
POORE, M.E.D. 1956. The use of phytosociological methods in ecological
investigations. IV. General discussion of phytosociological problems. J.
Ecol. 43: 606-651.
POTGIETER, J.W. 1982. 'n Plantekologiese studie van die Golden Gate
Hoogland Nasionale Park, Clarens, Oranje-Vrystaat. Unpublished M.Sc.
thesis, University of the Free State, Bloemfontein.
ROSSOUW, L.F. 1983. 'n Plantekologiese studie van die
boomgemeenskappe van die Bloemfonteinomgewing, Oranje-Vrystaat.
Unpublished M.Sc. thesis, University of the Free State, Bloemfontein.
SCHEEPERS,J.C. 1975. The plant ecology of the Kroonstad and Bethlehem
areas of the Highveld Agricultural Region. Unpublished D.Sc.
dissertation. University of Pretoria, Pretoria.
SCHEEPERS, J.C. 1987. Grassland Biome Project: Proceedings of the
workshop on the classification and mapping. S. Afr. Ecosys. Prog. Rep.
Series 16: 1-31.
SHIMWELL, D.W. 1971. Description and classification of vegetation.
Sidgewick and Jackson, London ..
SMITHEMAN, J. & PERRY, P. 1990. A vegetation survey of the Karoo
National Garden Reserve, Worcester. S. Afr. J. Bot. 56 (5): 525-541.
TOMLINSON, F.R. 1970. Optimale bodembenutting in die Landbou -'n nuwe
benadering. In: Optimale bodembenutting in die Landbou. pp. 7-11. Dept
of Agric. Tech. Serv., Pretoria.
TURNER, B.J. 1989. A phytosociological study of the south-eastern
Transvaal grasslands. M.Sc. thesis. University of Pretoria, Pretoria.
15
VAN WYK, S. 1983. 'n Plantekologiese studie van die Abe-Bailey-
Natuurreservaat. M.Sc. thesis, Potchefstroom University for C.H.E.,
Potchefstroom.
VAN WYK, S. & BREDENKAMP,G.J. 1986. 'n Braun-Blanquet klassifikasie
van die plantegroei van die Abe Bailey-Natuurreservaat. S. Afr. J. Bot.
52: 321-331.
WERGER, M.J.A. 1973. Phytosociology of the Upper Orange River Valley,
South Africa. Unpublished Ph.D. dissertation. University of Nijmegen.
WERGER, M.J.A. 1974. On concepts and techniques applied in the Zurich-
Montpellier method of vegetation survey. Bothalia 11: 309-323.
WERGER, M.J.A. 1980. Phytosociology of the Upper Orange River Valley,
South Africa. Mem. bot. Surv. S. Alr. 46: 1-222.
WHITTAKER, R.H. 1978. Classification of plant communities. W. Junk, The
Hague.
16
CHAPTER 2
Vegetation ecology of the southern Free State
Physical environment and major plant communities of the southern Free
State .
.. Submitted: Navorsinge vim die Nasionale Museum, Bloemfontein
17
CHAPTER 2
Physical environment and major plant communities of the southern Free
State.
2.1 INTRODUCTION
Ecosystems are organizations consisting of a unified group of components
forming a systematized whole (Kormondy 1996). According to 0' Neill et al.
(1986) an ecosystem consists of two or more components that interact and
is surrounded by an environment with which it mayor may not interact.
According to Acocks (1988) vegetation changes to the way it is treated.
This is the essential fact that must be grasped if one is to understand the
vegetation of a settled country like South Africa. There is little or no
vegetation in South Africa which is in its original condition (Acocks 1988).
Mentis & Huntley (1982) predicted that at the present rate of population
growth, being higher in South Africa than any other country in the world,
South Africans will have less cultivated land per person at the turn of the
century than is now available to the average person on earth. This situation
will lead to less natural pastures for cattle and game, and the demands on
the natural resources will still increase.
Since the large scale classification of vegetation by Acocks (1953, 1988)
much advance has been made towards more detailed classifications. Man
and animals are dependent on the natural resources and the need to
maximize the optimal use for these resources will definitely increase with
the growth of the human population. Grazing areas in particular need to be
. subdivided into ecologically homogeneous grazing units to ensure optimal
and sustainable utilization of forage resources (Tainton 1984, Danckwerts
& Teague 1989).
To enable optimal resource utilization and conservation, a vegetation
classification programme has been implemented in the Grassland Biome
(Mentis & Huntley 1982, Scheepers 1987). This Biome supports a major
portion of the country's maize, dairy, beef and timber industry and is
agriculturally the most productive biome in South Africa (Mentis & Huntley
18
1982, Rutherford & Westfall 1994). Optimal use of natural resources can
not be taken care of without adequate knowledge of the ecosystems
involved (Edwards 1983). Therefore, a classification of the vegetation of the
southern Free State was undertaken, as little is known about this
vegetation.
2.2 STUDY AREA
The present study includes the southern Free State and is situated to the
south of the 29° 00' S latitude and to the west of the 27° 00' E longitude,
encompassing approximately 27 000 km2 (Figure 2.1). Important cities and
towns situated in this area are Bloemfontein, Petrusburg, Fauresmith,
Bethulie and Zastron (Fi.gure2.1).
Acocks (1953, 1988) d.ivided the vegetation of the study area into 6
different veld types, while low & Rebelo identified 7 vegetation types within
the region (Figure 2.1). Two biomes can be distinguished, namely the
Grassland and Nama-Karoo Biomes (Rutherford & Westfall 1994) (Figure
2.2).
2.2.1 BIOMES IN THE SOUTHERN FREESTATE
Many attempts have been made to reduce the great spatial and temporal
complexity of man's natural environment into conceptually manageable
units. Many conflicting divisions of natural systems have been proposed and
mapped and most authors appear unperturbed by the plethora of differently
mapped units (Rutherford & Westfall 1994). Du Rietz (1965) counters that,
contrary to those biologists, who do not see .the forest for all its trees, the
phytosociologists of the present day agree that division of the living world
into biocoenoses (biomes) is necessary for conceiving, describing and
explaining the enormous diversity and variation of the mixed organism
populations (Rutherford & Westfall 1994).
19
According to Odum (1971) a biome is the largest land community unit
recognized at a continental or subcontinental level. A biome can therefore
not be restricted to a small localized area. A limit on scale for biomes is
essential to comply with the requirements of large natural areas in the
original definition and eliminates local types, such as fringing ravine forests,
cliff faces and various aquatic bodies in southern Africa. Kuchier (1949) is
one of the very few authors who take map scale into account when
applying physiognomic classifications of vegetation. Odum (1971) also
suggests that a biome should include an animal component as well.
According to Odum (1971) a biome is distinguished from other biomes
primarily on the basis of those climatic features that most affect the biota.
A very different view in the use of the term "biome" is that put forward
by Waiter & Box (1976) and Waiter (1979). A hierarchical system of
ecological units is presented where the term "biome" is used at various
levels together with a prefix. Hence we have, for example zonobiomes
(climate zones), orobiomes (mountains), pedobiomes (systems primarily
dependent on the soil), lithobiomes, halobiomes and peinobiomes. The
lowest levels of the hierarchy are denoted simply as biomes.
In formulating the criteria to determine the biome status of areas in
southern Africa, it appears that the animal component as a whole is not
necessarily a reliable criterion and that the primary criterion remains
dominant plant life form(s) (Rutherford & Westfall 1994).
2.2.1.1 GRASSLAND BIOME
The term "grassland" is well established, is effectively descriptive and is
preferred to the vernacular "grassveld", because of the former's local and
international acceptance (Rutherford & Westfall 1994). The topography is
mainly flat to rolling but can also be mountainous.
The main geological units are the Beaufort and Ecca Groups followed by
the Molteno, Elliot and Clarens formations, all of the Karoo Sequence, as
well as the Ventersdorp Supergroup (Figure 2.4).
20
Major rivers draining into the Atlantic Ocean are the perennial Vaal,
Caledon and Orange Rivers of which only the Caledon and Orange Rivers
flow through the study area.
The most common soil group in the Grassland Biome, accounting for just
under 50 % of the area, is the red-yellow-grey latosol plinthic catena. Soil
erosion in the Grassland Biome is limited in the higher rainfall areas due to
the high vegetation cover. However, where vegetation cover is reduced
through veld mismanagement, erosion can be severe, especially on steeper
slopes and erodable solonetzic duplex soils such as are found in Natal
(Rutherford & Westfall 1994).
The Grassland Biome (Figure 2.2) is limited to the summer and strong
summer rainfall areas with mean annual rainfall mostly between 400 and 2
000 mm per annum. The mean annual rainfall in the Grassland Biome within
the study area varies between 500 and 700 mm per annum (Figure 2.9).
The part of the Grassland Biome that has been invaded by karroid
elements is included in the Nama-Karoo Biome (Veld Type 36 of Aceeks.
1988) (Rutherford & Westfall 1994). There is some uncertainty regarding
the position of the south-western limits of the original grassland in this Veld
Type (Rutherford & Westfall 1994).
2.2.1.1.a VEGETATION
The vegetation of the Grassland Biome is physiognomically monolithic and is
characterized by strong dominance of hemicryptophytes of the Poaceae.
Canopy cover is moisture dependent and decreases with mean annual
rainfall. Grazing has a decisive influence on canopy structure (Rutherford &
Westfall 1994).
The vegetation of the Grassland Biome follows a rainfall gradient which
generally corresponds to the relative contributions to the plant cover by
"sweet" and "sour" grasses. Probably the most noteworthy species with
21
wide distribution in the Grassland Biome is Themeda triandra Forssk. The
number of rare plants in the Grassland Biome is not particularly large, but
increases in the wetter areas and mainly includes non-graminoid plants
especially geophytes (Hilton- Taylor 1996).
2.2.1.2 NAMA-KAROO BIOME
The term "Nama-Karoo" is a concatenation of Namaland of southern
Namibia and the Karoo of South Africa (Rutherford & Westfall 1994).
The Nama-Karoo Biome is found on the central plateau of the Cape
Province, north and the easterly tip of the western Cape folded mountain
belt, the southwestern Free State and the southern interior of Namibia. Most
of the area consists of extensive to undulating plains, interspersed with
mesas, hills or the occasional mountain (Rutherford & Westfall 1994).
The main stratigraphic units are the Beaufort and Ecca groups.
The most common soil group in the Nama-Karoo Biome, accounting for
over 80% of the area in South Africa, is lime-rich weakly developed soils.
Other soil groups include sands, combinations ot red clays and solonetzic
soils, and undifferentiated rocks and lithosols (Rutherford & Westfall 1994).
The soils are generally alkaline (pH 7.0 to 8.3) (Vorster & Roux 1983).
Accumulation of silt or clay is common in depressions and pans. Many of
the soil surfaces of the Nama-Karoo area are easily eroded by water and
wind. Where vegetation cover has been reduced by persistent overgrazing,
erosion of soil has reached an advanced level of degradation in many parts
(Rutherford & Westfall 1994). Where the sand veneer of some areas of arid
grassland is eroded away, dwarf shrubs invade (Tinley 1977).
This biome is limited to strong summer, summer and evenly spread
rainfall areas. Mean annual rainfall for most of the area ranges from about
100 to 500 mm (Rutherford & Westfall 1994). The Nama-Karoo· Biome
I
I
I
I
J
22
within the study area mainly falls within the 200-400 mm and 400-600 mm
per annum rainfall intervals (Figure 2.9).
2.2.1.2.a VEGETATION
The vegetation of the Nama-Karoo Biome is dominated by chamaephytes
and hemicryptophytes and can be described as a grassy, dwarf shrubland
(Edwards 1983). The hemicryptophytes of the biome are mainly C4
graminoids (Vogel et al. 1978). Plant species diversity and the number of
rare and endangered species in the biome are relatively low (Hall et al.
1980). Retrogression of plant composition is usually taken to start after
disturbance by overgrazing. The usual progression, given a significant
reduction in grazing pressure and a suitable distribution of rainfall (Vorster &
Roux 1983), is a steady increase in hemicryptophyte cover and a more
variable decrease in chamaephyte cover.
2.2.2 VEGETATION TYPES
Acocks (1953) compiled a veld type map of southern Africa. Since the
release of Acocks' "Veld Types of South Africa" in 1953, there was a quest
for a more detailed vegetation map. A vegetation map of South Africa,
Lesotho and Swaziland was compiled by Low & Rebelo (1996) and the
following vegetation types (from west to east) are present within the
southern Free State (Figure 2.1):
Vegetation type 51: Orange River Nama-Karoo
Vegetation type 50: Upper Nama-karoo
Vegetation type 32: Kimberley Thorn Bushveld
Vegetation type 52: Eastern Mixed Nama-karoo
Vegetation type 37: Dry Sandy Highveld Grassland
Vegetation type 39: Moist Cool Highveld Grassland
Vegetation type 40: Moist Cold Highveld Grassland
~ ---------_J II
23
DESCRIPTION OF THE VEGETATION TYPES
2.2.2.1 VEGETATION TYPE 51: Orange River Nama-karoo
This vegetation type is situated in the extreme western part of the study
area (Figure 2.1). Acocks (1988) refers to this area as the Orange Broken
Veld and it occurs within the hot, arid drainage basin of the Orange River
(Hoffman 1996 b). According to Acocks (1988) it takes the form of invasion
of the Vryburg scrub bush veld by Acacia mellifera and Acacia tortilis with
more or less of the Karoo constituent of the Orange River Broken Veld
prevailing in the Vaal River Valley.
2.2.2.2 VEGETATION TYPE 50: Upper Nama-karoo
This vegetation type is occupying the western part of the study area
between the Orange River Nama-karoo and the Eastern Mixed Nama-karoo
(Figure 2.1). This region occupies the central part of the upper plateau at an
altitude of between 1 050 and 1 700 m. The topography is generally flat
and stony but the area is dotted with hills and mountains (Hoffman 1996 c).
The vegetation is fairly grassy Karoo with Eragrostis lehmanniana and
Aristida congesta prominent. Bigger shrubs, such as Lycium spp. and
Rhigozum trichotomum randomly occur.
The flood plains sometimes retain a very dense, grassy, short Karoo
vegetation of which two forms occur: (i) dense short grassland and (ii)
dense short Karoo (Acocks 1988).
2.2.2.3 VEGETATION TYPE 32: Kimberley Thorn Bushveld
The Kimberley Thorn Bushveld occupies the north-western corner of the
study area (Figure 2.1). The summer rainfall varies between 400 and 500
mm per year. Sandy to loamy soils underlain by calcrete are prominent.
L_ . -
24
This is an open savanna with Acacia torti/is and A. erioloba prominent.
The shrub layer is poorly developed with Tarchonanthus camphoratus and
Acacia mellifera having scattered distributions. Natural grazing is important
in this vegetation type. The most important grasses present include
Enneapogon scoparius, Eragrostis lehmanniana, Elionurus muticus and
Cymbopogon plurinodis (Leistner 1967 & Bezuidenhout 1994).
2.2.2.4 VEGETATION TYPE 52: Eastern Mixed Nama-karoo
This vegetation type occupies the biggest part of the study area (Figure 2.1)
and scarcely differs in appearance from the Upper Nama-karoo. The Eastern
Mixed Nama-karoo reflects an extensive ecotone between the Nama-karoo
Biome in the west and the Grassland Biome in the east (Hoffman 1996 a). It
has more grassiness, especially in the eastern parts.
According to Acocks (1988), the hills are still essentially of grassland
type and complete grassland occurs in protected areas.
A complex mix of grass- and shrub-dominated vegetation types, which
are subject to dynamic changes in species composition dependent on
seasonal rainfall events, occur within this vegetation type (Hoffman 1996).
2.2.2.5 VEGETATION TYPE 37: Dry Sandy Highveld Grassland
This vegetation type lies in the eastern and south-eastern parts of the study
area (Figure 2.1). This is a dry grassland with a few Sweet Thorn Acacia
trees occurring only occasionally along water courses (Bredenkamp & Van
Rooyen 1996 al. The soils are mainly deep, red to yellow, apedal, aeolian
sand, often covering limestone. The presence of Karoo elements in the west
probably represent cuttiers of Karoo vegetation, but this should not
necessarily be considered as encroachment (Bredenkamp & Van Rooyen
1996 a).
25
2.2.2.6 VEGETATION TYPE 39: Moist Cool Highveld Grassland
This vegetation type occupies wetter country than the preceding type and is
located in the eastern parts of the study area (Figure 2.1). Deep, red
(Hutton) and yellow (Clovelly) soils, moistly of the Karoo Sequence
sediments occur. These soils are excellent for agronomy, and extensive
areas are cultivated for maize and other crops (Bredenkamp & Van Rooyen
1996 b). This Turf Highland is being strongly dominated by Themeda
triandra.
2.2.2.7 VEGETATION TYPE 40: Moist Cold Highveld Grassland
This is the veld of the sandy parts of the wetter, higher elevated portion of
the highveld in the Free State. This vegetation type falls within the high
rainfall regions of the study area which ranges from 600-800 mm/a (Figure
2.9). The vegetation is a moderately dense grassland and maintains its
density well.
Deep, yellow and grey sandy-loam soils derived from sandstones and
shales of the Beaufort Group occurs (Bredenkamp et al. 1996). The Karoo
invasion is well under way in this veld with patches of Pentzia globosa and
Felicia muricata developing on the heavier soil along eroded shale hillsides
(Acocks 1988).
2.2.3 GEOLOGY
Scheepers (1975) considers the geology of an area to be the basic
environmental factor of prime importance on an extensive scale, because
the geology influences the topography and thereby has an influence on the
climate, parent materials, soils and the vegetation (Du Preez 1991).
The study area is primarily underlain by the Beaufort, Ecca and
Stormberg Groups of the Karoo Sequence (Figure 2.4).
26
2.2.3.1 THE BEAUFORT GROUP
The Beaufort Group is subdivided into three divisions, i.e. the lower, middle
and upper series and consists primarily of red mudstone with cross-bedded
sandstone occurring frequently. The beds are rich in reptilian remains and
these fossils have been used as a basis for dividing the series into
paleontological zones (Du Toit 1954).
This group is subdivided into two subgroups i.e. the Adelaide Subgroup
which was deposited during the Upper Permian, and the Tarkastad
Subgroup which was deposited during the Lower Triassic (Figure 2.4, Du
Toit 1954).
2.2.3.1.a THE ADELAIDE SUBGROUP
This subgroup of the Beaufort Group is indicated on the map (Figure 2.4 ).
In the central part of the Free State, the Adelaide Formation consists of a
succession of fine-grained sandstone and coarse arkose, alternating with
green and brownish-red mudstone. The positioning of the accompanying'
Estcourt Formation is problematical, in the sense that, lithologically, it
resembles the rocks of the Ecca Group quite closely, but it is a time
equivalent of the Adelaide Subgroup and lies' directly below the Tarkastad
Formation. The Estcourt Formation is composed of an alternation of mainly
dark bluish-grey to nearly black, carbonaceous shale and pole-coloured, fine
to course-grained sandstone. Fossils occur fairly generally, and remains of
reptiles, fishes, insects and plants are known (Visser 1984).
2.2.3.1.b THE TARKASTAD FORMATION
This subgroup, with common lateral variation, forms the boundary between
the Palaeozoic and Mesozoic and was probably deposited during the Early
Triassic. In the lower part of this succession the percentage of sandstone is
higher than in the upper part (Du Toit 1954).
L_ __
27
2.2.3.2 THE ECCA GROUP
The Ecca Series mainly consists of shale and sandstone, with red mudstone
being absent. It is mainly dark-grey and Carbon-rich. The most important
coal deposits in South Africa are found in the Ecca Series, but only in Natal,
Free State and the Transvaal (Du Toit 1954). It also contains fossil plants
and shells, and tracks of small animals. Ryan (1967) recognized four faces
of the Ecca, namely the southern, western, central and northern.
2.2.3.2.a THE TIERBERG SHALE FORMATION
This formation is present in the western and northern marginal area of the
Karoo basin and is situated in the western parts of the study area (Figure
2.4). It represents the Central or Blue.Ecca and is almost entirely composed
of dark bluish-grey, laminated shale, rhythmically bedded shale and
siltstone, and a few thin layers of dark-grey sandstone (Du Toit 1954).
2.2.3.3 THE STORMBERG GROUP
The Stormberg Group consists of the Molteno, Elliot and Clarens formations
(Du Toit 1926).
2.2.3.3.a THE MOLTENO FORMATION
The Molteno Formation crops out within the Karoo basin and encircles the
Lesotho Highlands. This is the first formation of the Stormberg Group and
lies on top of the Beaufort Group. It consists of thick layers of glittering
sandstones, grits with subordinate grey and black shale, mudstones and
coals (Dingle et al. 1983).
28
2.2.3.3.b THE ELLIOT FORMATION
In the Karoo basin the Elliot Formation follows conformably on the Molteno
Formation and is composed of brownish-red and greenish-grey mudstone,
siltstone and shale, alternating with reddish sandstone (Dingle et al. 1983).
2.2.3.3.c THE CLARENCE FORMATION
Wherever the Karoo Sequence is fully developed, this formation is also
present. It consists of fine-grained, aeolian sandstone, which bears
testimony of the fact that the Late Triassic desiccation reached its climax in
this formation. The Clarens Formation lies on top of the Elliot Formation
(thus is not indicated in Figure 2.4) and its thickness varies considerably.
Fossils are uncommon in the Clarens Formation (Dingle et al. 1983).
2.2.3.4 ALLUVIUM, SAND AND CALCRETE
These are quaternary formations and include river-terrace gravel, vlei
deposits, deposits around springs, surface limestone, calcified dune sand,
alluvium and surface sand (Van Eeden 1972). Small patches are situated in
the north-western parts of the study area and in the southern part in the
region of Aliwal North. Due to only a limited occurrence it is not indicated in
Figure 2.4.
According to Du Toit (1926), the Ecca Series furnishes greyish and
brownish soils which are often more loamy than sandy and are better for
cultivation purposes. Shales of both the Ecca and Beaufort Series on
weathering give rise to clay minerals. When soils of the Beaufort Series
weather, sandy soils are derived from sandstone.
29
2.2.3.5 KAROO DOLERITE
This is a dark-grey to neatly black, dense ig_neousrock, which invaded the
rocks of the Karoo Sequence on a grand scale. Dolerite is mainly found as
dykes and sills. The southern folded part of the Karoo Sequence is, however
free from dolerite intrusions (Du Toit 1926). The most conspicuous form in
which dolerite weathers, is sandstone. This can be seen typically on the dry
northern koppie slopes. Principically as a result of mechanical weathering
the northern hill and koppie slopes are usually a mass of weathered rounded
doleritic boulders and stones without the formation of deep soils. The
southern slopes of the large and steep koppies and hills are usually
characterised by the presence of deeper soil. The deep nature of the soil on
the southern slopes is mainly due to the cooler and more humid conditions
which are characteristic of these slopes.
The Upper Orange River virtually flows only over strata of the Karoo
System, which are packed upon each other practically horizontally. In the
lower parts of the Upper Orange River downstream from the Vanderkloof
Dam, red to grey dune sand deposits locally occur (Werger 1973).
2.2.4 PHYSIOGRAPHY
Landscapes are of great importance for understanding the development and
distribution of soil and vegetation types (Scheepers 1975).
The study area can be classified into different terrain-morphological
classes (Figure 2.5, Eloff 1984).
To the south-west of the study area large pans are prominent
characteristics, while outliers of the Maluti Mountains contribute to the
mountainous appearance of the south-eastern parts. Dolerite outcrops in the
central parts produce. chains of hills, which are marked landscape features
over long distances.
L_ .__
30
According to Figure 2.5 the central and western parts of the study area
mainly consists of flat plains with a moderate to high relief, while the south-
eastern corner mainly consists of plateaux (landscapes where 50-80% of
the area have slopes of less than 8% and where the local relief differences
are greater then 90 ml with a moderate relief. The ridge veld and valley
landscape between Philippolis and Aliwal-North mainly occurs on Beaufort
sediments.
Plateaux don't occur regularly, but are prominent east of Zastron. These
plateaux mainly consist of different terraces which descend towards the
Orange River. Plateaux with a great local relief are found at Fauresmith and
luckhoff. The central and north-western parts of the study area mainly
consist of even plains with widely. dispersed hills and ridges. Uneven plains
with dispersed high ridges are restricted to the Philippolis area and the
Tussen-die-Riviere Game Farm near Bethulie (Eloff 1984).
2.2.5 RIDGES, KOPPIES AND MOUNTAINS
This terrain unit covers a·very small area mainly in the form of mountain
ranges and isolated mountains in the south-eastern Free State.' All of the
landscapes where 20-50% of the area contains slopes of less than 8%, fall
within this category. According to Eloff (1984) a terrain unit only qualifies
as a mountain when the relief differences are bigger than 300 m. The Thaba
'Nchu mountain near Thaba 'Nchu and Aasvoëlberg mountain near Zastron
are the most important elevations of this landscape in the southern Free
State.
2.2.6 SOilS AND LAND TYPES
2.2.6.1 SOILS
Soil is a natural entity which results from a complex of interactions between
climate, organisms, topography, parent material and time (Van der Merwe
1973). Jenny (1980) defines soil as a body of nature that has its own
31
internal organization and history of geneses. According to Eloff (1984) the
increase in rainfall from west to east plays an important role in the geneses
(development) of soil. Soils in the study area are heterogeneous due to the
great variation in parent material and topography (Figure 2.6).
Soils of the southern Free State are highly dissected and are drained by
the Orange, Riet, Modder and Caledon rivers. Alluvium brought down by
these rivers is deposited along the lower reaches and serves as arable soils.
The non-arable soils are of the Sterkspruit, Arcadia, Estcourt, Valsrivier and
Bonheim forms. Arable soils may be divided into two broad groups (i) soils
of alluvial or colluvial origin and (ii) soils of aeolian origin.
Alluvial soils are mainly of the Dundee soil form (Van der Merwe 1973)
and are classified as Fluvisols (FAO UNESCO 1987). Colluvial soils represent
various soil farms, e.g. Arcadia (Vertisals, FAO UNESCO 1987), Bonheim,
Shortlands (Luvisois, FAO UNESCO 1987) etc. (Van der Merwe 1973).
Dundee soils are deposited along river banks and are utilized under
irrigation. Arcadia soils under very careful management may be irrigated but
extreme care must be taken on account of the high clay content (Van der
Merwe 1973). Soils associated with streambeds are usually poorly drained.
Soils of the Estcourt (Planosols). Sterkspruit, Valsrivier (Luvisois),
Arcadia, Bonheim and Dundee farms are aften cultivated as drylands. The
first three mentioned forms are extremely suspectable to erosion and all
have horizons of high clay content (Van der Merwe 1973). The A-horizon is
easily washed away, exposing the erodable clayey B-horizon. According to
RusseIl (1997), soil can hold water because of the pores between soil
particles. The more pores the soil has, the more water can be stored
between the particles for use by the plant. The water hold efficiency of
sandy soils mainly depends on the amount of clay and humus it contains.
The clay and humus particles are the first to be removed by erosion (RusseIl
1997). Donga erosion follows as a rule, because of the collapse of the
highly sodium saturated B-horizon. Valsrivier soils have an orthic A- and red
pedocutanic B-horizon. This is mainly a sandy-clayish to clavish soil and is
underlain by a layer of sand loam (Eloff 1984). Bonheim and Arcadia soils
32
are more stable and the stability of the Dundee soils depend much upon the
nature of the alluvial layers. These soils are easily trampled. When denuded
from their natural grass cover, recovery is exceptionally slow and difficult.
Soils of aeolian origin are mainly of the Hutton and Bainsvlei forms
(Ferralsols, FAO UNESCO 1987). A notable feature of Hutton soils is the
dominance of a fine sand fraction. Fine sand often comprises over 80% of
the total sand and is well sorted round 0.1 mm. The clay content of these
soils increases with depth. The deeper the soil profile, the easier the
drainage of excess rainwater away from the roots (RusseIl 1997). These
soils are, furthermore, usually well-drained (Eloff 1984).
Soils of the Bainsvlei form have the same mother material as Hutton
soils, but the soft plinthic horizons of this soil form differentiate it from the
Hutton form. Hutton soils are generally well-drained, while Bainsvlei soils are
regarded as moderately drained (Eloff 1984).
2.2.6.2 LAND TYPES
The soils in the study area are classified on the basis of land types.
Researchers such as Bredenkamp & Theron (1978) and Bezuidenhout (1988)
have established that geology, soil and climate are important abiotic factors
which correlate well with vegetation communities. Therefore the land type
plays an important role in the first stratification of the study area
(Bezuidenhout 1993). Bezuidenhout (1993) compiled separate plant
sociological tables for each land type.
A land type denotes an area specific uniformity of pattern with respect to
terrain form, soil pattern and climate. Consequently one land type is
distinguished from another in terms of one or a combination of the following
parameters: terrain form, soil pattern or climate (Land Type Survey Staff
1985). Ten different land types are distinguished in the study area, namely
the Ae, Ag, Ca, Da, Db, De, Ea, Fa, Fb and Ib land types. Because of the
size of the study area and the resulted reduction of land type maps (2924
Koffiefontein, 2926 Bloemfontein, 3024 Colesberg and 3026 Aliwal North)
L- _
33
to be compiled into a single map, too much detail would have been lost. It
was thus decided not to include a detailed land type map. The distribution
of land types A, B, C, 0, E, F and I in the Free State are shown in Figure
2.7. The B land type, absent in the southern Free State (Figure 2.7), is thus
not discussed below.
DESCRIPTION OF THE LAND TYPES
2.2.6.2.1 A LAND TYPE
The A land type is generally found in the northern and north-western parts
of the study area (Figure 2.7) with Hutton and Clovelly soils being the most
prominent (Land Type Survey Staff, in press). Shallow, stony Glenrosa and
Mispah soils are prominent in the rocky areas, while Oakleaf, Sterkspruit
and other cutanic soils are associated with the plains and pans. These
apedal soils are well-drained and favoured for the production of cash crops
like maize. Thunder storms with high rainfall intensity result in a loss of soil
water by deep drainage, increasing production risk in the already dry
western Free State. The terrain units of the A land types of the southern
Free State are mostly plains with a low relief « 130 mm) and pans. They
generally have straight slopes of less than 5% with a low drainage density
and low stream frequency (Potgieter et al. 1995).
The Ae land type consists of red soils with a high base status. The
colour being due to ferric oxide around the particles (Werger 1978). The
soils are generally deeper than 300 mm and no dunes occur. The Ag land
type also has red soils with a high base status, but is generally less than
300 mm deep (Land Type Survey Staff, in press).
2.2.6.2.2 C LAND TYPE
C land types are found in the central northern parts. of the study area, west
of Bloemfontein and in the south-eastern corner of the study area in the
Zastron-District (Figure 2.7). This unit indicates land that qualifies as a
34
plinthic catena and indicates soil which in its perfect form is represented by
(in order from highest to lowest in the upland landscape) Hutton, Bainsvlei,
Avalon and Longlands forms. It has, in upland positions, margalitic (soils
with melanic and vertic horizons) and/or duplex soils (Swartland and
Sterkspruit soil forms) that combined cover more than 10% of the land type
(Land Type Survey Staff, in press). The C land type is more sensitive to
waterlogging than the A land type making it less suitable for irrigation
(Potgieter et al. 1995).
Dolerite outcrops of the Ca land type are conspicuous in the general
topography of the study area. Gravel and Sterkspruit- and Valsrivier soil
forms are prominent on slopes. The Valsrivier, Milkwood and Dundee soil
forms are dominant on the low-lying plains (Malan et al. 1995).
In the low-lying areas the soils are deep (> 1000 mm) and clayey
(Alfisois, Soil Survey Staff 1992). On the slopes the soils are shallow and
mainly of the Mispah form (Land Type Survey Staff, in press). These soils
are classified as Lithic Quartzipsamments (Soil Survey Staff 1992) and
Lithosols (FAO UNESCO1987) (Malan et al. 1995).
2.2.6.2.3 D lAND TYPE
D land types are prominent in the southern Free State (Figure 2.7). Units
Da, Db and Dc accommodate land where duplex soils occur and
prismacutanic and/or pedocutanic diagnostic horizons are prominent. Upland
soils that play duplex character include Estcourt, Sterkspruit, Swartland,
Valsrivier and Kroonstad farms. Kroonstad and Estcourt soils are limited to
the wetter areas of the Free State (Potgieter et al. 1995). These soils have
sandy A-horizons with clayey B-hortzons, The soils are drier than the plinthic
or apedal soils and therefore usually less productive. The "wet" soil forms,
Estcourt and Kroonstad, have a positive water balance resulting in subsoil
saturation for some time after the rainy season. This attribute can lead to
increased productivity of selected crops. Deep ploughing (more than 200
mm) results in the dispersive clays of the B-horizon being brought to the
L-____________________________________________________________________________ --
35
surface. A crust forms and penetration of water is slowed down. Runoff is
accelerated, erosion increased and a drier soil results (Potgieter et al. 1995).
Da refers to land where duplex soils with red B horizons comprise more
than half of the area covered by duplex soils while Db refers to land where
duplex soils with non-red B horizons comprise more than half of the area
covered by duplex soils. The Dc land type also has duplex soils, but more
than 10 % of the land type is made up of soil forms that have one or more
of the following diagnostic horizons: vertic, melanic and red structured
(Land Type Survey Staff, in press). According to Eloff (1984), limited
effective soil depth is the largest single limiting factor of duplex soils.
2.2.6.2.4 E LAND TYPE
E land types indicate land with a high base status and accommodate the
expansive soils. These soils are generally described with the term "vertic" .
The most abundant soil farms are the Arcadia and Rensburg farms. They
have a strong structure and form cracks in the dry state which close in the
rainy season. Generally, the clay content of these vertic soils is high.
Usually they are 800-1000 mm deep, but are often shallow and stony where
associated with outcrops of baste rocks like dolerite. These soils dry out
quickly and therefore have a low crop potential compared to sandy soils.
They are effectively utilized with crops like sunflower which are much better
adopted to these conditions; Vertic soils are difficult to manage and
although they are relatively fertile, they are considered marginal soils in the
drier parts of the Free State. Vertic soils in the dry Free State take up water
quickly as the water infiltrates through the cracks. Once expanded the
infiltration rate is low and the risk of erosion by runoff water higher. The
soils generally are resistant to dispersion, crust formation and degradation
(Potgieter et al. 1995).
__ . I
36
2.2.6.2.5 F LAND TYPE
The F land type is intended to accommodate pedologically young landscapes
that are not predominantly rock and not predominantly alluvial or aeolian
and in which the dominant soil forming processes have been rock
weathering, the formation of orthic topsoil horizons and commonly, clay
illuviation, giving rise to typically lithocutanic horizons. The soil forms which
epitomize these processes are Glenrosa and Mispah. The potential for crop
production is very low and cultivation should be avoided. Degradation risks
are water and wind erosion when the veld is degraded (Potgieter et al.
1995).
Fa refers to land in which lime .in the soil is not encountered regularly in
any part of the landscape while Fb indicates land where lime occurs
regularly in one or more valley bottom soils (Land Type Survey Staff, in
press).
2.2.6.2.6 I LAND TYPE
The I land types are miscellaneous soil groups varying from mountain slopes
to alluvial river banks. The attributes, potential and risk for degradation vary
with soil type (Potgieter et al. 1995).
The lb land type indicates land with exposed rock covering 60-80% of
the area. These rocky portions may be underlain by soil which would have
Qualified the unit for inclusion in another broad soil pattern was it not for the
surface rockiness (Land Type Survey Staff, in press). The Dundee and
Oakleaf soil forms are the most common soils associated with this land type
(Potgieter et al. 1995).
2.2.7 CLIMATE
Climate plays an important role in the land- and soil forming processes
(Strahler 1975). The entire study area is subjected to a summer rainfall
37
climate, although there are significant differences along the east-west
gradient. According to Acocks (1988) climate has a major influence on the
distribution of vegetation.
Precipitation and temperature are the most significant climatic factors in
vegetation development (Schultze & McGee 1978, Woodward & Williams
1987) and are therefore discussed below.
2.2.7.1 PRECIPITATION
Rainfall statistics are available from four weather stations in the study area.
Data are given in Figure 2.8.
The mean monthly rainfall for the weather stations Bloemfontein (1 351
m), Gariep Dam (1 291 m), Fauresmith (1 363 m) and Wepener (1 438 m) is
presented in Figure 2.8. This is mainly a summer rainfall area with most of
the annual rain falling during the summer months of November to April.
Precipitation is lowest during the winter months with June and July the
periods of minimum rainfall (Figure 2.8).
Strong precipitation gradients extend across the study area (Figure 2.9).
The average annual precipitation increases from west to east (Figure 2.9).
This is caused by the increasing relief and decrease of average daily
temperatures from west to east (Van der Wall 1976,· Schulze & McGee
1978).
According to Figure 2.9, the driest part of the study area is situated
within the 200-400 mm/a rainfall interval with the wettest part within the
600-800 mm/a interval. Figure 2.9 also shows the iso-evaporation lines in
the Free State. Evaporation decreases from west to east. In the south-
western corner (where the lowest rainfall also prevails) evaporation is as
high as 2 794 mm per annum, while it decreases systematically towards the
east (1 778 mm per annum). The lower rainfall accompanied with higher
evaporation rates explain the higher aridity of the western parts.
~----------------------------------------------------------------------------- -
38
2.2.7.2 TEMPERATURE
Topography has a definite influence on the temperature of the study area,
especially along the rivers (Barker 1985). The hottest months of the year are
from December to February with June and July the coldest months (Figure
2.10).
Although there is no big temperature difference between the western and
eastern parts of the study area, the western parts tend to be warmer (Figure
2.10).
In the study area the Gariep Dam has the highest mean annual
temperature of 16.7 °C, with Wepener the coldest at 15.5 °C. Figure 2.10
shows that the months of December and January are the months with the
highest extreme daily maximum temperatures and June and July the months
with the coldest extreme temperatures. Fauresmith is the town in the study
area with the biggest difference between the two extreme temperatures, 37
°C in June and 38°C during July. This is probably due to the topography in
which the town is situated.
2.2.7.3 CLIMATE DIAGRAMS
The climate diagrams of the four weather stations used in this study, are
presented in Figure 2.11 .
Figure 2.11 also indicates that the humid period (where rainfall exceeds
temperature in the diagram) in Bloemfontein stretches from middle
September to the end of April.
Wepener has the shortest period of drought (where temperature exceeds
rainfall in the diagram) and also has the highest annual rainfall of the
weather stations (Figure 2.11).
~--------------------~
39
2.3 METHODS
Relevés were compiled in 924 sample plots. Stratification was based on land
type, topographical position (crest, plateau or slope), aspect and geology.
Plot sizes were fixed on 16 m2 for grassland vegetation and 100 m2 for
woodland (shrubland) which is in accordance with Scheepers (1975),
Bredenkamp & Theron (1978), Du Preez (1979), Rossouw (1983), Van Wyk
(1983), Turner (1989), Malan (1992), Bezuidenhout (1993), Eckhardt
(1993), Fuls (1993) and Malan et al. (1995). In each sample plot, all species
present were recorded and their respective canopy cover values and/or
abundance recorded, according to the Braun-Blanquet cover-abundance
scale (Mueller-Dombois & Ellenberg 1974). Other environmental variables
such as soil type, land type, rockiness of the soil surface, erosion and
degree of utilization by herbivores were also recorded.
Two-way indicator species analysis (TWINSPAN) (Hill 1979 b) was
applied to the floristic data set in order to derive a first approximation of the
vegetation units of the area. Refinement was done by the application of
Braun-Blanquet procedures (Braun-Blanquet 1932 & 1964) and resulted in a
phytosociological table. From the final phytosociological table, seven major
plant communities were identified. A synoptic table was compiled for the
communities (also see Fuls 1993). A procedure of successive
approximation, including the recently proposed method for large data sets
(Bredenkamp & Bezuidenhout 1995), was applied to the data set.
An ordination algorithm, DECORANA (Hill 1979 a), was also applied to
the floristic data to illustrate the floristic relationships between plant
communities. Taxa names conform to those of Arnold & De Wet (1993).
2.4 RESULTS AND DISCUSSION
A schematic presentation of the hierarchical classification and associated
environmental interpretation of the seven major vegetation units of the
study area is presented in Figure 2.12. Unit numbers refer to the numbers in
Table 2.1.
40
A simplified terrain form sketch, compiled from Land Type Survey Staff
(In press), is presented in Figure 2.13. Terrain unit 1 represents plateaux,
terrain unit 2 the crests, terrain unit 3 and 4 rocky slopes of hills and terrain
unit 5 the lower-lying plains as well as drainage channels.
By far the most dominant species in the study area is the grass,
Themeda triandra (species group 80, Table 2.1). Other species with high
constancies are Protasparagus suaveolens, P. laricinus, Eragrostis
lehmanniana, E. curvula, Melolobium candicans, Chenopodium album,
Sporobolus fimbriatus, Chrysocoma ci/iata and Lycium cinereum (species
group 80, Table 2.1).
Conspicuous trees and shrubs occasionally encountered include Acacia
torti/is, Tarchonanthus camphoratus (species group 13), A. mellifera
(species group 14), Rhus erose, Grewia occidentalis, Osyris lanceolata, Rhus
pyroides subsp. pyroides, Rhamnus prinoides (species group 25), Felicia
filifolia, Rhigozum obovatum, Euclea crispa subsp. ovata (species group 49),
Diospyros austro-africana (species group 50), Rhus burchetlii, R. lancea, R.
ciliata, Ehretia rigida (species group 51), A. karroo (species group 71), D.
Iycioides (species group 79), Protasparagus suaveolens, Lycium cinereum
and P. laricinus (species group 80, Table 2.1).
The following major vegetation units were distinguished (Figure 2.12):
(1) shrubland of the rocky outcrops;
(2) shrubland of the drainage lines;
(3) grassland of the undulating plains and crests of rocky outcrops; and
(4) hygrophylic vegetation of the stream beds and wetlands.
1 SHRUBlAND OF THE ROCKY OUTCROPS
This vegetation unit includes the tree and shrub communities associated
with the rocky outcrops within the study area. The vegetation type occurs
on isolated dolerite or sandstone rocky outcrops (Terrain units 1, 2, 3 and 4,
41
Figure 2.13). Dolerite hills and ridges occur throughout the study area, but
sandstone ridges are nearly restricted to the south-eastern corner of the
study area in the Zastron district. In some cases the exposed rocks may
consist of a combination of dolerite and sandstone with mudstone and/or
shale sometimes present.
Species of species group 19 are diagnostic within this vegetation group
and include the fern Pellaea ca/ome/anos and the forbs Hermannia modesta,
Po/yga/a hottentottica and Arqvrotobium pauciflorum (species group 19,
Table 2.1).
This vegetation unit can be divided into three distinct sub units (Table
2.1) .
1.1 LEUCOSIDEA SERICEA - STOEBE PLUMOSA SHRUBLAND OF
THE MOIST EASTERN PARTS
This vegetation unit is restricted to the south-eastern parts of the study area
near Zastron. The Molteno Formation is the most important geological unit
and the Avalon soil form is the most prominent.
The vegetation often is very dense, especially in the ravines where
Leucosidea sericea (species group 11),· Myrsine africana, Euc/ea crispa
subsp. crispa, the exotic Rosa eg/anteria (species group 1) and Rhus dentata
(species group 3) dominate (Table 2.1).
Diagnostic species are listed in species group 1 (Table 2.1) and include
the trees and shrubs Euc/ea crispa subsp. crispa, Rhus dregeana, Budd/eja
sa/viifolia and Rhus pyroides subsp. gracilis. Passerina montana, Myrsine
africana, Cliffortia nitidute, Rosa eg/anteria and the fynbos shrub C/iffortia
paucistaminea (species group 1) are the most abundant shrubs. Diagnostic
grasses are scarce with only Tristachya /eucothrix (species group 1) present
(Table 2.1).
'--- 1
42
Other prominent trees and shrubs include Rhus erosa, Grewia
occidentalis, Osyris lanceolata, Rhamnus prinoides, Olea europaea (species
group 12), Felicia filifolia (species group 46), Diospyros austro-africana
(species group 47), Rhus burchellii (species group 48) and Diospyros
Iycioides (species group 80). Pellaea calomelanos (species group 6) and
Cheilanthes eckloniana (species group 46) are the most important ferns
present. Important grasses encountered include Digitaria eriantha (species
group 35), Heteropogon contortus (species group 46), Cymbopogon
plurinodis (species group 77), Tnemeae triandra and Eragrostis curvula
(species group 81).
A detailed description of this vegetation type is presented in Chapter 3 of
this dissertation.
1.2 BUDDLEJA SAlIGNA - OLEA EUROPAEA SHRUBLAND OF THE
DRY CENTRAL PARTS
This shrubland is restricted to the steep slope (generally > 30°) (Terrain
units 1 & 4) with a high percentage of surface rock. Geologically this area is
underlain by the Beaufort and Ecca Groups in the drier parts (rainfall < 500
mm/a) of the study area (Figure 2.9).
The diagnostic species within this vegetation unit are listed in species
group 2 (Table 2.1) and are virtually restricted to graminoids. The only
woody species present are Boscia albitrunca, Protasparagus cooperi, P.
denudatus and May tenus heterophylla (species group 2, Table 2.1).
Other dominant species within this vegetation unit include: the woody
species, Buddleja saligna (species group 3), Rhus erosa, Osyris lanceolata,
Olea europaea subsp. africana, Euclea crispa subsp. ovata, Protasparagus
striatus, Felicia filifolia (species group 46), Diospyros austro-africana, Ehretia
rigida (species group 47), Rhus burchellii, R. ciliata, R. lancea (species group
48) and Diospyros Iycioides (species group 80). Solanum coccineum
(species group 12), Protasparagus suaveolens and P. laricinus (species
group 81) are the most important semi-woody species.
43
Among the graminoids Eustachys paspaloides (species group 45),
Elionurus muticus (species group 38), Aristida congesta, Heteropogon
contortus (species group 46), Aristide diffusa (species group 48),
Fingerhuthia africana (species group 68), Cymbopogon plurinodis (species
group 77), Enneapogon scoparius (species group 79), Themeda triandra,
Eragrostis lehmanniana, Sporobolus fimbriatus and Eragrostis curvula
(species group 81) are the most abundant (Table 2.1).
The ferns Pellaea calomelanos (species group 19) and Cheilanthes
eckloniana (species group 49) are sometimes very abundant, especially in
high-lying rocky habitat.
This vegetation type is discussed in more detail in Chapter 4 of this
dissertation.
1.3 ACACIA MELLIFERA - ACACIA TORTILIS SHRUBLAND OF THE
DRY WESTERN PARTS OF THE STUDY AREA
This vegetation unit occurs on the upper slopes and plateaux of rocky hills
and ridges as well as on the rocky crests of high undulating terrain (terrain
units 2 & 3, Figure 2.13).
The diagnostic species of this vegetation unit are listed in species group
4 (Table 2.1) of which the shrub, Grewia flava, is the most important.
Prominent woody species include Acacia erioloba and A. hebeclada (species
group 4, Table 2.1). The rest of the species listed in species group 4 all
have low constancies (Table 2.1).
Ziziphus mucronata (species group 36), Rhigozum obovatum (species
group 46) and Ehretia rigida (species group 48) are the, most important
woody species with the shrub Protasparagus laricinus (species group 81),
the most abundant semi-woody species.
44
The herbaceous layer is presented by Eriocepha/us ericoides (species
group 35), E. spineseens (species group 58), Barleria rigida, (species group
67), Pentzia g/obosa (species group 69), Talinum caffrum (species group
78), Protasparagus suaveo/ens, Chrysocoma ciliata and Chenopodium a/bum
(species group 81). Important grasses Cymbopogon excavatus (species
group 13), Digitaria eriantha (species group 35), Aristida congesta,
Heteropogon contortus (species group 46), Aristida diffusa (species group
48), Fingerhuthia africana (species group 68), Enneapogon scoparius
(species group 79), Themeda triandra, Eragrostis lehmanniana, E. curvula
and Sporobo/us fimbriatus (species group 81).
A more detailed discussion on this vegetation type is presented in
Chapter 5 of this dissertation.
2 SHRUBlAND OF THE DRAINAGE CHANNELS
This shrubland occurs throughout the study area on terrain unit 4 (Figure
2.13) which constitutes gradually sloping terrain.
This vegetation unit occurs on all soil types within the study area and is
characterized by the species listed in species group 7 (Table 2.1), with the
exotic Sa/ix baby/onica the most important.
The drainage channels are dominated by the trees Acacia karroo (species
group 69), Diospyros Iycioides (species group 80) and the shrub,
Protasparagus laricinus (species group 81).
Prominent trees encountered, include Rhus pyroides subsp. pvroides,
Ce/tis africana, Olea europaea subsp, africana (species group 12), Ziziphus
mucronata (species group 36), Diospyros austro-africana (species group 47)
and Rhus /ancea (species group 48).
Dominant shrubs are scarce with only Rhus burchellii, R. ciliata (species
group 48), Lycium cinereum (species group 81) and L. hirsutum (species
group 65) present (Table 2.1).
45
Species typically associated with wetlands and periodically waterlogged
areas, are Cyperus longus, Salix mucronata and Phragmites australis
(species group 54), further characterize this vegetation unit.
Numerous forbs are also present and include Zinnia peruviana (species
group 12), Hermannia coccocerpe, Verbena bonariensis (species group 32),
Artemisia afra (species group 43), Rumex lanceolatus (species group 55),
Xanthium strumarium (species group 61), Tribulus terrestris (species group
69), Berkheya pinnatifida, Tagetes minuta, Walafrida saxatilis (species group
76), Protasparagus suaveolens, Melolobium candicans, Chenopodium album
and the Karoo encroacher species Chrysocoma ciliata (species group 81).
Important graminoids include Eragrostis obtusa, Panicum maximum
(species group 69), Themeda triandra, Eragrostis lehmanniana, E. curvula
and Sporobolus fimbriatus (species group 81).
More detail of this vegetation type is presented in Chapter 6 of this
dissertation.
3 GRASSLAND VEGETATION OF THE UNDULATING PLAINS AND
CRESTS OF ROCKY OUTCROPS
The -grassland vegetation of the study area covers approximately 80% of
the study area and is restricted to terrain units 1, 2, 3 and 4 (Figure 2.13).
This vegetation unit occurs on all soil types. Species of species group 26
are diagnostic of this vegetation unit and include the forbs Becium
angustifolium, Flaveria bidentis, Hermennie linearifolia, Senna italica and
Kyllinga alba (species group 38, Table 2.1).
Numerous graminoids with a wide ecological amplitude characterize this
grassland. The most important are Aristida congesta (species group 46), A.
diffusa (species group 48), Eragrostis obtusa (species group 69), E.-
lehmanniana and E. curvula (species group 81). Important dwarf shrubs
include Nidorella resedifolia (species group 64), Pentzia globosa {species
'-------------- __ 1
46
group 69), Walafrida sexetilis (species group 76) and Chrysocoma ciliata
(species group 81, Table 2.1). All of the above mentioned species have a
constancy of 20% and higher (Table 2.1). These species, singly or
collectively; often comprise more than 80% of the total vegetation cover.
This vegetation unit does not have a strongly developed woody component
and can be further divided into two distinct plant communities (Table 2.1).
3.1 ARISTIDA CONGESTA - ARISTIDA DIFFUSA GRASSLAND OF THE
DISTURBED AND RETROGRESSED AREAS
This vegetation unit is restricted to terrain units 1, 3 and 4 (Figure 2.13) and
are restricted to poorly drained soil in disturbed and retrogressed areas. The
diagnostic species are listed in species group 14 which includes only one
tree species, the exotic Prosopis velutina and two grass species, Eragrostis
bergiana and E. truncata (Table 2.1).
This vegetation type is rather characterized by the scarcity of woody
species. The only shrubs present are Eberlanzia spinosa, Euphorbia
mauritanica (species group 17), Euryops multifidus (species group 24),
Tercnonenthus camphoratus (species group 35),· Rhigozum obovatum,
Euclea crispa subsp. ovata (species group 46), Rhus ciliata and R. burchel/ii
(species group 48), all of which have a low constancy (Table 2.1). Tree
species encountered include the exotic Schinus molle (species group 18),
Acacia torti/is (species group 35), and Rhus lancea (species group 48).
Nearly all the graminoids encountered have a low constancy and include
Tetrachne dregei (species group 27), Enneapogon cenchroides (species
group 29), Tragus koelerioides, Urochloa panicoides (species group 31),
Cenchrus cilieris, Digitaria eriantha (species group 35), Setaria sphacelata,
Eragrostis nindensis, Melinis repens, Triraphis andropogonoides (species
group 42), Aristida congesta, Heteropogon contortus, Eragrostis superba
(species group 46), Fingerhuthia africana (species group 68) and Setaria
incrassata (species group 73).
47
Numerous forb species occur, all of which have low constancies and
include Becium angustifo/ia, Flaveria bidentis, Hermannia /ineare, Senna
ita/ica, Kyllinga a/ba (species group 26), Mestok/ema tuberosum (species
group 29), Hermannia coccocarpa, Verbena bonariensis, Nenax microphylla
(species group 32), Eriocepha/us ericoides (species group 35), Sa/via
disermas (species group 41), Melianthus comosus (species group 42), Oxalis
depressa, Se/ago a/bida (species group 44), Sesamum capense and So/anum
incanum (species group 46).
Forbs normally associated with overgrazed vegetation with constancy
values of 40% and higher include Schkuhria pinnata (species group 66),
Pentzia g/obosa (species group 69), Berkheya onopordifolia (species group
75), B. pinnatifida, Tagetes minutaand Sa/via verbenaca (species group 76).
The grasses Ch/oris virgata (species group 68) and Eragrostis obtusa
(species group, 69) are also indicative of overgrazed conditions.
This vegetation type is discussed in more detail in Chapter 7 of this
dissertation.
3.2 THEMEDA TRIANDRA - DIGITARIA ERIANTHA GRASSLAND ON
WELL-DRAINED SOIL
This vegetation unit is primarily associated with moist and well-drained soils.
The habitat is mostly relatively undisturbed south-facing slopes (terrain units
1, 3 & 4).
In contrast with the Aristida congesta - Aristida diffusa grassland, this
grassland is dominated by Themeda triandra (species group 81) and Digitaria
eriantha (species group 35, Table 2.1). Other important graminoids
encountered, include Setaria. sphace/ata (species group 42), Aristida
congesta, Heteropogon contortus (species group 46), A. diffusa (species
group 48), Eragrostis obtusa (species group 69), Cymbopogon pturinodis
(species group 77), Panicum cotoretum (species group 79), Eragrostis
/ehmanniana, Sporobo/us fimbriatus and E. curvu/a (species group 81).
48
The diagnostic species are listed in species group 25 (Table 2.1). Trees
and shrubs are scarce and inconspicuous. The herbaceous layer further
characterizes this vegetation unit with Nidorella resedifolia (species group
64), Schkuhria pinnata (species group 66), Pentzia globosa (species group
69), Berkheya onopordifolia (species group 75), Walafrida saxatilis,
Berkheya pinnatifida, Tagetes minuta and Salvia verbenaca (species group
76) and Chrysocoma ciliata (species group 81) the most important (Table
2.1).
This vegetation type is discussed in more detail in Chapter 8 of this
dissertation.
4 HYGROPHILlC VEGETATION OF THE STREAM-BEDS AND
WETLANDS
This vegetation unit is typical of streambeds and wetlands and is restricted
to the low-lying areas of the study area (terrain unit 5, Figure 2.13). Most
species associated with this vegetation unit occur on seasonally or
permanently waterlogged soils.
The diagnostic species are listed in species group 49 with Juncus
kraussii, Portulaca oleracea and Persicaria serrulata the only species
attaining a constancy of 40%.
Broadly, this wetland can be classified as the Asclepias fruticosa -
Juncus kraussii wetland with Asclepias fruticosa (species group 76) having
a constancy of 60% (Table 2.1). Forb species contribute most to the
species richness of the wetlands. The species composition varies greatly
between the different wetland habitats, especially when the vegetation of
the stream-beds is compared with that of the drier habitats such as pans of
the flat to undulating areas.
Species of species groups 49-81 are all associated with this vegetation
type (Table 2.1). The most important are Cyperus rupestris (species group
50), Sporobolus ioclados (species group 52), Lobelia thermalis (species
49
group 53), Cyperus longus (species group 54), Lactuca dregeana (species
group 55), Cirsium vulgare (species group 63), Nidorella resedifolia,
Mariscus congestus (species group 64), Cyperus marginatus, Cynodon
incompletus (species group 65) and Senecio consanguineus (species group
79, Table 2.1).
Woody species are virtually absent from this vegetation unit. The most
important are the shrub, Rhigozum trichotomum (species group 68), and the
trees, Acacia karroo (species group 69) and Diospyros Iycioides (species
group 80).
The hygrophilic vegetation of the stream-beds and wetlands of the
southern Free State is discussed in more detail in Chapter 9 and the pan
vegetation in Chapter 10 of this dissertation .
. ORDINATION
In the scatter diagram the distribution of the syntaxa along the first and
second axes of the DECORANA ordination is given (Figure 2.14). Along the
first axis the woodland syntaxa (1.1, 1.2, 1.3 & 2) are to the left and middle
of the diagram, the grassland syntaxa (3.1 & 3.2) to the middle and right
and the syntaxa associated with wetlands and pans (4) to the right of the
diagram. Also illustrated on the first axis is a gradient which is related to
altitude and rockiness of the soil .surtace. Axis 2 illustrates a moisture
gradient. Syntaxa to the top of the diagram are associated with relatively
wetter habitat conditions than those to the bottom of the diagram (Figure
2.14).
2.5 CONCLUDING REMARKS
The seven vegetation sub-units (four major vegetation units, Figure 2.12)
are easily distinguishable in the southern Free State. All these plant
communities have their own sets of environmental and ecological variables
and conditions, but overlapping exists (Figure 2.14). Consequently, each of
50
these plant communities should be regarded as an unique managerial and
ecological unit.
A detailed classification and ecological interpretation of each of these
plant communities will be presented and will form an integral part of the
long-term goal to compile a comprehensive synecological and
syntaxonomical synthesis of the Grassland Biome of southern Africa
(Scheepers 1987).
Table 2.1: Synoptic table ot the rnalor vegetation units ot the southern Free
State.
Vegetation unit number 1112334
123 12
SPECIES GROUP 1
Passerina montana 3
Stoebe plumosa 3
Cliffortia nitidula 2
Cliffortia paucistaminea 2
Euclea crispa subsp. crispa 2
Myrsine africana 2
Rosa eglanteria 2
Senecio isatideus 2
Aloe ferox 1
Buddleja salviifolia 1
Crassula capitella 1
Dicoma anomala 1
Gnidia microcephala 1
Helichrysum appendiculatum 1
Helichrysum nudifolium 1
Helichrysum pilosellum 1
Indigofera nigromontana 1
Linum thunbergii 1
Pelargonium alchemilloides 1
Peucedanum capense i
Rhus dregeana 1
Rhus pyroides subsp. gracilis 1
Tristachya leucothrix 1
V~rnonia capensis 1
SPECIES GROUP 2
Achyranthes aspera 1
Aloe broomii 1
Boophane disticha 1
Boscia albitrunca 1
Bromus catharicus 1
Cheilanthes hirta 1
Cineraria lobata 1
Comrnelinabenghalensis 1
Cotyledon orbiculata 1
Crassula nudicaulis 1
Crassula setulosa 1
Dimorphotheca cuneata 1
Ehrharta erecta 1
Eriochloa parvispiculata l
Garuleum pinnatifidum 1
Gerbera piloselloides 1
Homeria pallida 1
Kleinia longifolia 1
Lepidium africanum 1
1112334
Plant community number
123 12
Lithospermum cinereum 1
May tenus heterophylla 1
Mohria caffrorum 1
Opuntia vulgaris 1
Peliostomum leucorrhizum 1
Pennisetum sphacelatum 1
Pentarrhinum insipidum 1
Protasparagus capensis 1
Protasparagus cooperi 1
Protasparagus denudatus 1
Rhynchosia totta 1
Salvia repens 1
Schoenoxiphium sparteum 1
Silene undulata
Sisymbrium capense 11
Stapelia grandiflora 1
Trachyandra aspera
Urtica dioica 1
Vicia sativa 11
Withania somnifera 1
SPECIES GROUP 3
Buddleja saligna
Clutia pulchella 1321
Cussonia paniculata
Rhus dentata 2121
Sutera filicaulis 21
Cotoneaster sp: 11
Delosperma pottsii
Eragrostis racemosus 1111
Haemanthus humiIis 11
Kalanchoe paniculata 11
Prunus persica 11
Rhynchosia nervosa 11
Turbina oblongata 11
SPECIES GROUP 4
Grewia flava
Abutilon pycnodon 2
Acacia erioloba 1
Acacia hebeclada 11
Alternanthera pungens
Commicarpus pentandrus 1
Dimorphotheca zeyheri 1
Heliophila carnosa 1
Justicia protracta 1
Melhania rehmannii 11
1112334
Plant community number
123 12
SPECIES GROUP 5
Corbichonia decumbens 11
Kedrostis africana 11
Pachypodium succulentum 11
Pupalia lappacea 11
Scilla nervosa 11
SPECIES GROUP 6
Pellaea calomelanos 321
Argyrolobium pauciflorum 111
Herrnannia modesta 111
Polygala hottentotta 111
SPECIES GROUP 7
Salix babylonica 3
Conium chaerophylloides 1
Datura ferox 1
Equisetum ramosissimum 1
Gomphostigrna virg.atum 1
Hernarthria altissima 1
Leucas martinicensis . 1
Mentha longifolia 1
Polygonum kitaibelianum 1
Scirpus inanis 1
SPECIES GROUP 8
Polygala uncinata 11
SPECIES GROUP 9
Crassula lanceolata 1 2
Achyranthes aquati~a 1 1
Cineraria lyrata 1 1
Heteromorpha trifoliata 1 1
Phyla nodiflora 1 1
Pollichia campestris 1 1
Setaria verticillata 1 1
SPECIES GROUP 10
Sonchus oleraceus 111
SPECIES GROUP 11
Leucosidea sericea 3 1
SPECIES GROUP 12
Rhus erosa . 53 1
Grewia occidentalis 31 1
Osyris lanceolata 32 1
Rhus pyroides subsp. pyroides 11 3
1112334
Plant community number
123 12
Rhamnus prinoides 31 1
Melica decumbens 11 1
Clematis brachiata 11 3
Celtis africana 21 3
Zinnia peruviana 11 2
Olea europaea subsp. africana 33 3
Solanum coccineum 12 1
SPECIES GROUP 13
Cymbopogon excavatus 2111
Pavonia burchellii 2111
Lantana rugosa 1111
SPECIES GROUP 14
Amaranthus thunbergii 1
Aptosimum marlothii 1
Aptosimum spinescens 1
Convolvulus boedeckerianus 1
Deverra denudata 1
Drosanthemum species 1
Eragrostis bergiana 1
Eragrostis truncata 1
Galenia africana 1
Geigeria ornativa 1
Hertia ciliata 1
Mariscus capensis 1
Phyllanthus maderaspatensis 1
Plinthus karooicus - 1
Prosopis velutina 1
Psilocaulon junceum 1
Pteronia incana 1
Pterothrix spinescens 1
Rosenia humiIis 1
Ruschia rigida 1
Salsola calluna 1
Sarcocaulon salmoniflorum 1
Stachys hyssopoides 1
Suaeda fruticosa 1
Zygophyllum macrocarpon 1
Zygophyllum microphyllum 1
SPECIES GROUP 15
Blepharis diversispina 1 1
Eriocephalus aspalathoides 1 1
Justicia cuneata 1 1
Saltera sarcocolla 1 1
Schmidtia kalahariensis 1 1
Schmidtia pappophoroides 1 1
1112334
Plant community number ... ..
123 12
Thesium strictum 1 1
SPECIES GROUP 16
Aptosimum indivisum 1 1
Lightfootia nodosa 1 1
panicum stapfianum 1 1
Senecio longifolia 1 1
SPECIES GROUP 17
Eberlanzia spinosa 11 1
Euphorbia mauritanica 11 1
Pteronia glauca 11 1
Stipagrostis namaquensis 11 1
SPECIES GROUP 18
Schinus molle 1 11
SPECIES GROUP 19
Sutera pinnatifida 1 1
SPECIES GROUP 20
Sutera atropurpurea 1 11
SPECIES GROUP 21
Viscum rotundifolium 12 1
Lightfootia albens 11 1
SPECIES GROUP 22
Teucrium trifidum 11 11
SPECIES GROUP 23
Indigofera sessilifolia 111 1
SPECIES GROUP 24
Euryops multifidus 11111
SPECIES GROUP 25
Amrnocharis coranica 1
Chasmatophyllum musculinum 1
Cullen obtusifolia 1
Dipcadi glaucum 1
Helichrysum species 1
Hermannia cuneifolia 1
Hypoxis filiformis 1
Lotononis listii 1
Microchloa caffra 1
Oenothera indecora. 1
Papaver aculeatum 1
1112334
Plant community number
123 12
Senecio erubescens 1
Tragopogon dubius 1
Veronica anagilis-aquatica 1
Wahlenbergia undulata 1
SPECIES GROUP 26
Becium angustifolium 11
Flaveria bidentis 11
Hermannia linearifolia 11
Kyllinga alba 11
Senna italica 11
SPECIES GROUP 27
Tetrachne dregei 111
SPECIES GROUP 28
Kyphocarpa angustifolia 1 1
Pogonarthria squarrosa 1 1
SPECIES GROUP 29
Enneapogon cenchroides 1 11
Mestoklema tuberosum 1 11
Prosopis chilensis 1 11
SPECIES GROUP 30
Argemone ochroleuca 1 1
Arctotis venusta 1 1
Bidens bipinnata 1 1
Brunsvigia radulosa 1 1
Crotalaria eremicola 1 1
Elephantorrhiza elephantina 1 1
Enneapogon scaber 1 1
Eragrostis chloromelas 1 1
Eragrostis gummiflua 1 1
Euphorbia rectirama 1 1
Helichrysum dregearium 1 1
Helichrysum zeyheri 1 1
Indigofera alternans 1 1
Monsonia angustifolia 1 1
Moraea spathulata 1 1
Opuntia sp. 1 1
Pelargonium abrotanifolium 1 1
Pseudognaphalium luteo-album i 1
Solanum supinum 1 1
Sphaeralcea bonariensis 1 1
Sporobolus discoporus 1 1
Turbina oenotheroides 1 1
~ . __ I
1112334
Plant community number
123 12
SPECIES GROUP 31
Tragus koelerioides 1 Il
Urochloa panicoides 1 Il
SPECIES GROUP 32
Hermannia coccocarpa 1 211
Verbena bonariensis 1 211
Nenax microphylla 1 111
SPECIES GROUP 33
Acacia mellifera 14 1
Commelina africana Il 1
Hermannia comosa Il 1
Plexipus pinnatifidus Il 1
Senecio hastatus Il 1
SPECIES GROUP 34
Convolvulus arvensis 1 1 1
Sida dregei 1 1 1
SPECIES GROUP 35
Digitaria eriantha 32 14
Eriocephalus ericoides 12 21
Acacia tortilis 14 Il
Tarchonanthus camphoratus 24 11
Hermannia vestita 12 Il
Stachys rugosa 21 11
Cenchrus ciliaris 13 Il
Commelina eckloniana Il 11
SPECIES GROUP 36
Ziziphus mucronata 22311
Osteospermum muricatum 11111
SPECIES GROUP 37
Helichrysum rugulosum 2 1
Delosperma cooperi 1 1
Eragrostis capensis 1 1
SPECIES GROUP 38
Elionurus muticus 12 1
Hibiscus pusillus 11 1
Populus canescens Il 1
Salvia namaensis 11 1
Salvia stenophylla 11 1
Senecio burchellii 11 1
Tragus racemosus 11 1
1112334
Plant community number
123 12
SPECIES GROUP 39
Melolobium microphyllum 1 1 1
SPECIES GROUP 40
Scabiosa columbaria 1 1 1
SPECIES GROUP 41
Salvia disermas 1 11
SPECIES GROUP 42
Setaria sphacelata 11 12
Eragrostis nindensis 11 Il
Melianthus comosus Il
Melinis repens 1111 11
Triraphis andropogonoides 11 11
SPECIES GROUP 43
Artemisia afra 11 3 1
Oxalis corniculata 21 1 1
Pentzia sphaerocephala 21
Thesium sp. 1 111 1 1
SPECIES GROUP 44
Oxalis depressa 21 111
Selago albida 11 111
SPECIES GROUP 45
Eustachys paspaloides 121
Geigeria filifolia 1111
Phyllanthus parvulus 1111
Melinis nerviglume 1111 1
Solanum panduriforme 111 1
SPECIES GROUP 46
Felicia filifolia 531
Rhigozum obovatum 11213 11
Aristida congesta 232 23
Cheilanthes eckloniana 331 11
Euclea crispa subsp. ovata 141 11
Heteropogon contortus 344 12
Protasparagus striatus 121
Eragrostis superba 11211 11
Helichrysum callicomum 111 11
Opuntia ficus-indica
Sesamum 111 Ilcapense
Solanum 111 11incanum 111 11
SPECIES GROUP 47
1112334
Plant community number
123 12
Diospyros austro-africana 5212 1
SPECIES GROUP 48
Rhus burchelIii 341211
Aristida diffusa 233122
Ehretia rigida 123111
Rhus lancea 121411
Hermannia bryoniifolia 112111
Rhus ciliata 141211
SPECIES GROUP 49
Juncus kraussii 2
Persicaria serrulata 2
Portulaca oleracea 2
Alternanthera nodiflora 1
Barleria rnacrostegia 1
Cichoriurn intybus 1
Convolvulus sagittatus 1
Cyperus eragrostis 1
Cyperus laevigatus 1
Cyperus sp. 1
Diplachne fusca 1
Eragrostis bicolor 1
Medicago polyrnorpha 1
Phragrnites rnauritianus 1
Pulicaria scabra 1
Schoenoplectus paludicola 1
Scirpus dioecus- 1
Sporobolus tenellus 1
Walafrida densiflora 1
SPECIES GROUP 50
Cyperus rupestris 12
Agrostis lachnantha 11
Eragrostis plana 11
Fuirena hirsuta 11
Juncus rigidus 11
Scirpus nodosus 11
Sporobolus virginicus 11
SPECIES GROUP 51
Cynodon dactylon 1 11
SPECIES GROUP 52
Sporobolus ioclados 1 2
Aristida canescens 1 1
Atriplex nummularia 1 1
Osteospermurn spineseens 1 1
1112334
Plant community number
123 12
Zygophyllum incrustatum 1 1
SPECIES GROUP 53
Lobelia thermalis 112
Medicago sativa 111
panicum schinzii 111
SPECIES GROUP 54
Cyperus longus 5 2
Phragmites australis 3 1
Salix mucronata 3 1
Juncus exsertus 1 1
Miscanthus capensis 1 1
Nicotiana glauca 1 1
Ranunculus multifidus 1 1
Typha capensis 1 1
SPECIES GROUP 55
Rumex lanceolatatus 2 11
Lactuca dregeana 1 12
SPECIES GROUP 56
Lycium pilifolium 11 1
SPECIES GROUP·57
Rumex crispus 1111
SPECIES GROUP 58
Eriocephalus spinescens 221
SPECIES GROUP 59
Helichrysum lineare 1 111
SPECIES GROUP 60
Solanum retroflexum 1 11
Sutera aurantiaca 1 11
SPECIES GROUP 61
Oenothera rosea 1 1
Xanthium strumarium 11 3 1
SPECIES GROUP 62
Bulbine narcissifolia 1 1 1
Limeum aethiopicum 1
Stipagrostis ciliat~ 1 11 1 1
SPECIES GROUP 63
Cirsium vulgare 1 1 12
1112334
Plant community number
123 12
SPECIES GROUP 64
Hertia pallens 1 211
Nidorella resedifolia 1 122
Mariscus congestus 1 112
Atriplex semibaccata 1 111
Conyza bonariensis 1 111
SPECIES GROUP 65
Cynodon incompletus 1 1112
Cyperus marginatus 1 1112
Lycium hirsutum 1 3111
SPECIES GROUP 66
Schkuhria pinnata 11 21
Xanthium spinosum 11 11
SPECIES GROUP 67
Barleria rigida 12 1 1
Thesium hystrix 11 2 1
Lycium horridum 12 2 1
Eragrostis echinochloidea 11 1 1
Protasparagus mucronatus 11 1 1
SPECIES GROUP 68
Sal sola glabrescens 11 311
Pentzia incana 11 211
Chloris virgata 11 121
Fingerhuthia africana 13 211
Helichrysum pentzioides 11 111
Rhigozum trichotomum 11 111
Sal sola kali 11 111
Stipagrostis obtusa 11 111
Stipagrostis obtusa 11 111
SPECIES GROUP 69
Acacia karroo 115111
Eragrostis obtusa 112331
Pentzia globosa 231431
Tribulus terrestris 123111
Panicum maximum 113111
SPECIES GROUP 70
Helictotrichon turgudulum 2 1
SPECIES GROUP 71
Hyparrhenia hirta 21 1
Sutherlandia microphylla 11 1
1112334
Plant community number
123 12
1112334
Plant community number
123 12
Eragrostis curvula 3223231
Protasparagus suaveolens 1343211
Melolobium candicans 1112211
Chenopodium album 1132111
Sporobolus fimbriatus 1232121
Lycium cinereum 1113311
Protasparagus laricinus 1225111
51
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58
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-
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59
CHAPTER 3
Vegetation ecology of the southern Free State
Vegetation ecology of the southern Free State: Plant communities of
the Zastron area
* Submitted: South African Journal of Botany
60
CHAPTER 3
Vegetation ecology of the southern Free State: Plant communities of
the Zastron area
,.
P.W. Malan , H.J.T. Venter & P.J. du Preez
Department of Botany & Genetics, University of the Free State, p.a. Box
339, Bloemfontein, 9300
Keywords: Braun-Blanquet vegetation classification, DECORANAordination,
habitat related, southern Free State, TWINSPAN.
...
To whom correspondence should be addressed.
ABSTRACT
An analysis of the plant communities of the Zastron area (South Africa) is
presented. The Braun-Blanquet-technique, supplemented by TWINSPAN,
was used for the phytosociological classification of the vegetation. Twenty
distinct plant communities were recognized and described. An hierarchical
- classification is presented and each vegetation unit is related to specific
environmental characteristics. A DECORANA ordination is also presented,
showing environmental gradients.
3.1 INTRODUCTION
Each plant community may be regarded as an unique entity with its own
species composition associated with a specific set of environmental factors.
According to Westhoff (1971) the description of plant communities is
-essential to provide a scientific inventory for conservation and in general for
the preservation of biotic diversity; The fact that Acocks' (1988) broad
analysis and description of South African vegetation types is one of the
61
most cited botanical publications, indicates the importance and need for
such vegetation classifications. The necessity to identify and describe the
Grassland and Nama Karoo Biomes was stated by Mentis & Huntley (1982),
SCheepers (1986) and Hilton-Taylor (1987).
From a phytosociological viewpoint, relatively little is known about the
vegetation of the southern Free State and this data set and resulting
classifications provide the basis for a phytosociological synthesis of the
vegetation of the southern Free.State which is currently under study by the
authors. This paper specifically reports on the detailed Braun-Blanquet
classification and plant-ecological interpretation of the plant communities of
the Zastron area.
3.2 STUDY AREA
The study area covers approximately 1 270 km2 and is situated between
27° 00' and 27° 30' E longitude and 30° 00' and 30° 40' S latitude in the
south-eastern part of the southern Free State (Figure 1). The study area lies
within the Cymbopogon- Themeda Veld (Veld type 48, Acocks 1953) and
within the 600-800 mm rainfall interval. (Figure 1).
According to Acocks (1988), Karoo invasion is we" under way in the
Southern Variation of the Cymbopogon- Themeda Veld with patches of
Pentzia globosa, Walafrida saxatilis and Felicia fi/ifolia, developing on the
heavier soil forms. along valleys and eroded shaly hillsides. This phenomenon
is we" illustrated in Table 3.1 (species groups V, Wand Z).
Geologically the area is characterized by Molteno and Elliot Formations.
The uppermost formation, namely the Clarens Formation, forms a prominent
cliff on the northern side of Aasvoëlberg. The endangered Cape Vulture
(C;YPS coprotheres) used to breed here. The Molteno Formation, the first of
the Stormberg Group, lies on top of the Beaufort Group. The Elliot Formation
follows conformably on the Molteno Formation (Dingle et al. 1983). The
topography of the area consists mainly of continuous hills and mountains
_I
62
with moderate and high relief, allowing only stock farming and small-scale
crop production.
The Ca and Ib land types are the most prominent in the study area (Land
Type Survey Staff, In Press).
The Ca land type qualifies as a plinthic catena (which is represented by
Hutton-, Bainsvlei-, Avalon- and Longlands soil forms) (Land Type Survey
Staff, in press). Dolerite outcrops are conspicuous in the general topography
of the study area. Loose scree, as well as Mispah, Sterkspruit and Valsrivier
soil forms are prominent on slopes while Valsrivier, Milkwood and Dundee
soil forms are prominent on the low-lying plains (Malan et al. 1995).
The Ib land type accommodates land where exposed rocks cover 60-
80% of the soil surface. These rocky portions may be underlain by soil
. which would have qualified the unit for inclusion in another broad soil
pattern would it not have been for the surface rockiness. Dundee and
Oakleaf soil forms are the most common soils within this land type (Land
Type Survey Staff, in press).
Generally the soils in the Zastron area are referred to as "Podsolic" (pH
< 7) soils. This soils are generally deeper than "solonetic" [pH > 7 and
contains a high salt (especially sodium compounds) content] soils and also
comprises well-developed horizons. Donga and surface erosion are a
common phenomenon of these soils (Potgieter et al. 1995).
Altitude ranges from 1 350-2 000 m above sea level.
3.3 METHODS
Relevés were compiled in 76 sample plots. Stratification was based on
topographical position (crest, plateau or slope), aspect and geology. Plot
sizes were fixed on 100 m2 (10 m x 10 m) (Scheepers 1975). In each
sample plot the floristic composition was recorded and a cover-abundance
value according to the Braun-Blanquet scale (Braun-Blanquet 1964) was
63
allocated to each species. Other environmental variables such as soil form,
land type, percentage rockiness of the soil surface and habitat disturbance
were also recorded.
Two-way indicator species analysis (TWINSPAN) (Hill 1979 b) was
applied to the floristic data set and refined by the application of Braun-
Blanquet procedures that resulted in a phytosociological table (Table 3.1).
An ordination algorithm, DECORANA (Hill 1979 a) was also applied to
the· floristic data to analyse the floristic relationships between plant
communities. Taxa names conform to those of Arnold & De Wet (1993). No
attempt was made to formally distinguish between different sub species,
except for Euclea crispa subsp. crispa and E. crispa subsp. ovata and Rhus
pyroides subsp. gracilis and R. pyroides subsp. pyroides, because these sub
species occur in different habitats (Venter & Joubert 1985). According. to
Coates Palgrave (1984), Euclea crispa subsp. crispa has a very widespread
distribution, while E. crispa subsp. ovata has a restricted distribution in the
southern Free State and extends down to Cradock and Middelburg in the
Eastern Cape and westwards to Kimberley and Kuruman in the Northern
Cape. According to Venter & Joubert (1985), Rhus pyroides subsp. pyroides
is common in open veld, ravine or stream bank scrub throughout the whole
of the Free State, except the north-eastern corner. Rhus pyroides subsp,
gracilis, however, is restricted to forest margins and along river banks in the
north-eastern corner of the Free State (Venter & Joubert 1985).
3.4 RESULTS AND DISCUSSION
In this study the classification of the vegetation was achieved by way of the
floristic-sociological approach with the essential viewpoint that plant
communities are units of classification based primarily on species
composition (Mueller-Dombois & Ellenberg 1974, Whittaker 1978). The
general vegetation of this area can be considered as the Themeda trienare-
Otee europaea vegetation unit (species AB & group AC, Table 3.1).
According to Fuls (1993) variations in moisture and microclimate are related
to differences in irradiation due to different aspects and gradients.
64
Three major plant communities, of which one (major community 1) is not
further divided into distinct communities and sub-communities, have been
recognized and are illustrated in the phytosociological table (Table 3.1). The
hierarchical classification of these communities is summarized as follows:
1 Cliffortia nitidu/a-Rhus erosa Major community
2 Stoebe p/umosa-Leucosidea sericea Major community
2.1 Leucosidea sericea- Themeda triandra Community
2.2 Stoebe p/umosa-Elionurus muticus Community
2.3 Stoebe p/umosa-Peucedanum capense Community
2.4 C/iffortia paucistaminea-Passerina montana Community
2.5 Leucosidea sericea-Pe/argonium a/chemilloides Community
2.6 Hyparrhenia hirte-Osvris /anceo/ata Community
2.6.1 He/ichrysum rugu/osum-Leucosidea sericea Sub-community
2.6.2 Rhus dregeana-Leucosidea sericea Sub-community
3 a/ea europaea-Rhus burchellii Major community
3.1 Euc/ea crispa subsp. crispa-Rhus dentata Community
3.2 C/utia pu/chella-Diospyros /ycioides Community
3.2.1 Jemesbrittenie atropurpurea-Rhus erosa Sub-community
3.2.2 Rhus /ancea-Ce/tis africana Sub-community
3.3 Protasparagus suaveo/ens-Eragrostis /ehmanniana Community
3.3.1 Cymbopogon excavatus-Protasparagus suaveo/ens Sub-community
3.3.2 Eragrostis curvu/a-Sutera a/biflora Sub-community
3.3.3 Chei/anthes eck/oniana- Tragus koeterioides Sub-community
3.3.4 a/ea europaea-Me/ianthus comosus Sub-community
3.3.5 a/ea europaea-Wa/afrida saxatilis Sub-community
3.4 A/oe ferox-Rhigozum obovatum Community
3.4.1 A/oe ferox-Setaria incrassata Sub-community
3.4.2 A/oe ferox-O/ea europaea Sub-community
3.5 Rhus cillete-Olee europaea Community
3.6 Euc/ea crispa subsp. ovata-O/ea europaea Community
65
DESCRIPTION OF THE COMMUNITIES
1 Cliffortia nitidula-Rhus erosa Major Community
A plant community which was found to be restricted to the moderately
steep east-facing footslopes of the Aasvoëlberg Mountain, where Avalon
soils are the most prominent. The Elliot and Molteno Formations are the
most important geological formations with the Ca land type covering nearly
80% of the area. These areas are often disturbed by hikers and have a low
species diversity (Table 3.1).
Species of species group A (Table 3.1) characterize this plant community
with Cliffortia nitidula (species group A) the most conspicuous, having high
cover-abundance values. According to Coates Palgrave (1984), C. nitidula
can reach six metres in height. However, the average height of C. nitidula in
this major community did not exceed three metres. The only other
conspicuous species present include the woody shrub, Rhus erosa (species
group Z, Table 3.1). R. erosa is commonly found in the rocky areas in the
southern Free State (See Chapter 4).
2 Stoebe plumosa-Leucosidea sericea Major community
This vegetation unit is encountered on the wet or slightly moist, steep
southerly facing slopes (30°- 60°), where also a higher species diversity is
found to be present (Table 3.1).
The diagnostic species are those listed in species group J (Table 3.1).
Leucosidea sericea is the only diagnostic tree species being abundant in
some areas. The height of this tree varies from two to six metres and is
widely dispersed in the mountainous areas, especially in kloof forests and on
mountain slopes in the Free State (Venter & Joubert 1985). The exotic rose,
Rosa eglanteria (species group J) has long pendulous branches which are
spinose. This species often forms dense impenetrable stands. Passerina
66
montana and Stoebe plumosa (species group J) are the only two other
diagnostic species present (Table 3.1).
Seven· distinct vegetation units were identified within this plant
community (Table 3.1).
2.1 Leucosidea sericea- Themeda triandra Community
The Leucosidea sericea- Themeda triandra Community is encountered on the
virtually undisturbed moist, steep (30°-60°) slopes, facing south-south-east
to south-south-west. Large dolerite and sandstone boulders occur and cover
40-60% of the soil surface.
In the absence of diagnostic species, Themeda triandra (species group
AC, Table 3.1) has a high constancy and canopy cover. Other species
present include Stoebe plumosa, Passerina montana, Leucosidea sericea,
Rosa eglanteria (species group J), Rhus erosa and Rhamnus prinoides
(species group Z). According to Coates Palgrave (1984), L. sericea can
reach up to seven metres in height and usually occurs at high altitudes
along streams and in ravines, as was also the case in this instance. In
KwaZulu-Natal, Leucosidea is troublesome as it invades overgrazed and
disturbed areas, forming impenetrable thickets which are best eradicated by
chopping plants down to ground. In mountainous areas the presence of
these trees is taken -as an indication that the streams are suitable for trout-
stocking (Coates Palgrave 1984).
2.2 Stoebe plumosa-Elionurus muticus Community
This plant community is associated with open shrubland at the feet of
southerly facing hills. This vegetation unit thrives in full sun. Large uneven
and rough rock plates occur and cover 50% of the soil surface.
The grass species, Elionurus muticus (species group B), is the only
differentiating species present (Table 3.1). According to Van Oudtshoorn
67
(1991) this species is well adapted to rocky habitat. Patches are severely
utilized and disturbed, especially by the rock dassie (Procavia capensis). Fuls
(1993) also reports patch-like over-utilization by rock dassies, especially on
southerly facing slopes of the low thicket communities of rocky outcrops in
the northern Free State. The forb Stoebe plumosa (species group .J) is
indicative of disturbed areas. Themeda triandra (species group AC) is the
only dominant grass species (Table 3.1).
2.3 Stoebe plumosa-Peucedanum capense Community·
This plant community is restricted to the feet of cool south-facing slopes.
Although dolerite may be present, these slopes consist predominantly of
sandstone ledges. Fine gravel may be present, but the soil is primarily
clayish, especially in the lower-lying localities.
Like the Stoebe plumosa-Elionurus muticus Community of the Stoebe
plumosa-Leucosidea sericea Major Community, no diagnostic woody species
occur. Peucedanum capense (species group C) differentiates this community
(Table 3.1). Noteworthy is the locally high cover-abundance of Leucosidea
sericea and the absence of the thorny, exotic rose, Rosa eglanteria (species
group j). Other important woody species are Diospyros Iycioides, D. austro-
africana, Rhus erosa and Rhamnus prinoides (species group Z). According to
Coates Palgrave (1984), a decoction of the decorticated root of R. prinoides
is taken as a blood purifier and to treat pneumonia. Parts of this plant are
widely favoured as a protective charm which is used against lightning, to
protect homes and to safeguard the courts of Basuthu chiefs (Coates
Palgrave 1984).
2.4 Cliffortia paucistaminea-Passerina montana Community
This plant community is encountered at the feet of south to south-west-
facing slopes. Rocks and pieces of fine, gravel are vislble on the soil surface.
Large sandstone boulders occur at these footslopes.
68
Apart from Cliffortia paucistaminea (species group D) and Passerina
montana (species group J), this plant community does not have a dominant
or conspicuous woody component. The small forb species, Oxalis
corniculata (species group D), together with C. paucistaminea, are the only
two diagnostic species with the latter having a notably high cover-
abundance (Table 3.1). Leucosidea sericea (species group J) has a relatively
low cover-abundance and is, together with Rhus erosa (species group Z),
the only woody species present (Table 3.1).
2.5 Leucosidea sericea-Pelargonium alchemilloides Community
This plant community is restricted to the lower altitudes' of moist plateaux of
dolerite hills. Flat rock slabs are prominent and cover 60-70% of the soil
surface.
Diagnostic tree species are absent with only the species of species group
E characterizing this vegetation unit (Table 3.1). Leucosidea sericea,
Passerina montana (species group J), Myrsine etricsns, Rhus dentete.
Euclea crispa subsp crispa (species group L), Osyris lanceolata (species
group S), Felicia filifolia, Diospyros austro-africana, Rhus erosa and
Rhamnus prinoides (species group Z) are the only shrubs present, all with a
maximum height not exceeding two metres - probably due to the rockiness
of the substratum.
2.6 Hyparrhenia hirta-Osyris lanceolata Community
This plant community is mainly associated with moist and, cool south-facing
slopes of the Aasvoëlberg Mountain near Zastron. The slopes are aften cliff-
like.
The presence of the grass, Hyparrhenia hirta (species group M), the most
widespread of all the hyparrhenias (Gibbs RusseIl et al. 1990), together with
the species from species group J) differentiate this vegetation unit (Table
3.1) .. H. hirta, commonly known as "dektamboekiegras" is a perennial,
69
rhizomatous grass which grows well in stony soils (Gibbs RusseIl et al.
1990). The vegetation often is dense with Leucosidea sericea (species
group J) often exceeding four metres in height. The tree, Osyris lanceolata
(species group S), the exotic rose, Rosa eglanteria (species group J), and
the shrub, Rhus erosa (species group Z), are the only other widely
distributed woody species.
Two distinct sub-communities were identified (Table 3.1).
2.6.1 Helichrysum rugulosum-Leucosidea sericea Sub-community
This very limited plant community was encountered on footslopes of
southerly facing hills. The area is rocky and large sandstone boulders (> 2
m in diameter) cover 60~70% of the soil surface. This is an important
thoroughfare for hikers and thus resulted in the degradation of the
vegetation due to trampling.
The diagnostic species are listed in species group F (Table 3.1).
Helichrysum rugulosum and the grasses Helictotrichon turgudulum, Setaria
sphacelata and Eragrostis nindensis are the most widely distributed among
these species. Leucosidea sericea, Rosa eglanteria (species group J), Osyris
lanceolata (species group S) and Rhus erosa (species group Z) are the most
abundant woody species with Hyparrhenia hirta (species group M) and
Themeda triendrs (species group AC) the grasses with the highest cover-
abundance (Table 3.1). Themeda triandra has a higher cover-abundance in
this vegetation unit than in the Rhus dregeana-Leucosidea sericea Sub-
community (Table 3.1).
2.6.2 Rhus dregeana-Leucosidea sericea Sub-community
This sub-community is associated with the moist and cool south-facing
slopes. These slopes predominantly consist of sandstone ledges, often being
cliff-like. The slopes are moist and cool due to the shading by the cliffs. The
70
vegetation is dense and the rocky slabs covering 60-70% of the soil surface
give the area a rocky appearance.
This moist shrubland is typical of the mountainous areas of the eastern
Free State, Lesotho, Natal and eastern Cape and has been described by
several botanists (Sews 1917, West 1951, Story 1952, Killick 1959,1963,
Roberts 1966, Edwards 1967 & Du Preez 1991). According to Roberts
(1966), the Leucosidea sericea-Myrsine africana forest of Thaba 'Nchu
Mountain is more closely related to the mesophytic bush and moist forest
communities of the eastern Cape, as described by Story (1952), than to the
shrublands of the Natal Midlands, as reported by Killick (1959, 1963). Du
Preez (1991) stated that the Leucosidea sericea-Budd/eja saligna moist
shrubland of Korannaberg occurs on sites where conditions are too harsh for
the development of ravine forest or in places where destruction of forest
took place.
Species of species group H (Table 3.1) characterize this vegetation unit
with Rhus dregeana the only diagnostic woody species present. The only
other diagnostic species present, is Aristea cognata. The grass Tristachya
/eucothrix and the small fern, Pellaea ca/ome/anos (species group I) are
evident, especially between the rock slabs. Only a few other woody species
occur with Leucosidea sericea (species group J), Rhus dentata, Euc/ea
crispa subsp. crispa, Myrsine africana (species group L), Budd/eja sa/viifolia
(species group 0), Osyris /anceo/ata (species group S), Diospyros /ycioides
and Rhamnus artnotdes (species group Z) being the most important (Table
3.1). Species of species groups Land 0 are prominent within this
vegetation unit, but are absent within the Helichrysum rugu/osum-
Leucosidea sericea Sub-community. The latter also lacks Rhamnus prinoides
(species group Z) which is prominent within this vegetation unit (Table 3.1).
3 Olea europaea-Rhus burchellii Major Community
This open woodland major community is associated with the ravines as well
as moist south- and south-east facing slopes of hills. The habitat conditions
71
here are drier than in the previous two major communities (major
communities 1 and 2). The soil surface is rocky and of doleritic origin.
Species of species group AB (Table 3.1) are diagnostic. Olea europaea
subsp. africana and Rhus burchellii (species group AB) are the differentiating
species with Euclea crispa subsp. ovata also abundant (Table 3.1). Other
widely distributed woody species include the tree Diospyros Iycioides and
the shrubs D. austro-africana, Felicia filifolia and Rhus erosa (species group
Z, Table 3.1).
Six distinct plant communities further characterize this major vegetation
unit (Table 3.1).
3.1 Euclea crispa subsp. crispa-Rhus dentata Community
This shrubland is restricted to the rocky ravines at the foot of south-facing
slopes. Stones and fine gravel from upslope occur on the soil surface.
This is a inconspicuous vegetation unit with only a few diagnostic
species. Thesium sp., Delosperma cooperi and Cussonia paniculata (species
group K) are the diagnostics of this community, all having low cover-
abundance values (Table 3.1). Myrsine africana, Rhus dentata, Euclea crispa
subsp. crispa (species group L), Buddleja salviifolia (species group 0), Osyris
lanceolata (species group S), Rhigozum obovatum, Grewia occidentalis
(species group Y), Diospyros Iycioides, D. austro-africana, Rhus erosa
(species group Z), R. burchellii and Olea europaea subsp. africana (species
group AB) are the most abundant woody species. present. Among the
graminoids Hyparrhenia bine (species group M) and Themeda triandra
(species group AC) are the most abundant (Table 3.1).
72
3.2 Clutia pulchella-Diospyros Iycioides Community
A shrubland community situated at low altitude on south-facing hills. The
soil is poorly drained and dolerite rock sheets cover large areas (50-70%) of
the soil surface. Pieces of fine sandstone gravel eroding from upslope are
common.
Clutia puIcheIla (species group P) differentiates this plant community.
According to Coates Palgrave (1984), C. pulchella occurs over a wide range
of altitudes and in a variety of habitats, from karroid scrub to evergreen
forests. Venter & joubert (1985), however, emphasized that this species
commonly occurs in shady ravines and below large trees. This was mainly
the case here, as Clutia pulchella grows well in the shade of especially
Diospyros Iycioides (species group Z) and Rhus lancea (species group Q).
Species of species groups B, C, G, H, I, R and X are absent from this
community (Table 3.1). S.pecies of species groups S, Z, AB and AC (Table
3.1) occur widespread with Osyris lanceolata (species group S), Diospyros
austro-africana, D. Iycioides, Rhus erosa (species group Z), Rhus burchellii,
Olea europaea subsp. africana (species group AB) the most important
woody species and Aristida diffusa (species group AB) the only conspicuous
grass. The small fern, Cheltenthes eckloniana (species group S), grows
especially well in the cracks between rock sheets, but is inconspicuous
here.
This vegetation unit is further subdivided into two distinct sub-
communities (Table 3.1).
3.2.1 Jamesbrittenia atropurpurea-Rhus erosa Sub-community
This sub-community occurs in low altitude areas on south-facing hills and
along streambeds where a sandy deposit often overlies the rock sheets. No
loose scree is visible and the soil is of a clayish nature.
This sub-community is characterised by the species listed in group N
(Table 3.1). Besides these diagnostic species, all of which have low cover-
73
abundance values, Diospyros /ycioides and especially Rhus erosa have high
cover-abundance values (species group Z, Table 3.1). It further differs from
the Euc/ea crispa subsp. crispa-Rhus dentata Community in the presence of
C/iffortia nitidu/a and Rhus pyroides subsp. gracilis (species group A), as
well as the higher cover-abundance of, Diospyros austro-africana, D.
/ycioides, Rhus erosa (species group Z) and Rhus burchellii (species group
AB), and the absence of the grass, Hyparrhenia hirta (species group M).
Besides Themeda triandra (species group AC) with a low constancy, Aristida .
diffusa (species group AB) is the only other graminoid with a high constancy
and cover-abundance values (Table 3.1).
3.2.2 Rhus /ancea-Ce/tis africana Sub-community
This vegetation unit is situated at low altitudes and is restricted to drainage
channels at the footslopes of south-facing hills. Gravel and sandstone
stones occur on the soil surface.
Species of species group Q differentiate this community with Rhus
/ancea and Ce/tis africana the only two diagnostic woody species. Buddleja
salviifolia (species group 0) and Rhus erosa (species· group Z) are absent
within this vegetation unit (Table 3.1). Diospyros Iycioides (species group
Z), Rhus burchellii and Olea europaea subsp. africana (species group AB) are
among the other conspicuous woodv species. Diospyros Iycioides,
especially, is very abundant and Rhemnus prinoides (species group Z) and
Euclea crispa subsp. ovata (species group AB), though inconspicuous, are
also present (Table 3.1).
3.3 Protasparagus suaveolens-Eragrostis lehmanniana Community
This plant community is associated with moist habitat conditions at the
midslopes of south-facing slopes. Habitat disturbance is a more common
phenomenon than in the Clutia pulchella-Diospyros Iycioides Community.
50%-60% of the soil surface is covered with dolerite and sandstones
stones.
74
Walafrida saxatilis, Protasparagus suaveolens and Eragrostis lehmanniana
(species group W) are the diagnostic species of this vegetation unit (Table
3.1). Also conspicuous are Diospyros Iycioides, Rhus erosa (species group
Z), R. burchellii and Olea europaea subsp. africana (species group AB), none
of which are higher than two metres.
This community can be subdivided into five sub-communities (Table 3.1).
3.3.1 Cymbopogon excavatus-Protasparagus suaveolens Sub-community
This plant community occurs on low altitudes of the midslopes, especially
along the disturbed, moist rocky areas of low south-facing hills. Due to the
. rockiness of the soil surface, especially in the lower-lying areas, standing
water is visible for weeks after good rains.
Species listed in species group R characterize this vegetation unit (Table
3.1) of which the grass, Cymbopogon excavatus, and the shrub,
Tarchonanthus camphoratus, have the highest cover-abundance values
(Table 3.1). C. excavatus, commonly known as Broad-leaved Turpentine
Grass is highly unpalatable to livestock due to the terpentine smell of its
leaves (Van Oudtshoorn 1991). The semi-parasite Viscum rotundifolium
(species group R) is virtually restricted to Tarchonanthus camphoratus.
According to Coates Palgrave (1984), splinters of T. camphoratus are
poisonous, causing septic sores which are difficult to heal. It provides good
fuel, burning even when green. Zulu women use the leaves to perfume their
hair (Coates Palgrave 1984).
3.3.2 Eragrostis curvula-Sutera albiflora Sub-community
This plant community has a restricted distribution and is present on the
midslopes of the south-facing slopes of low hills. The soil surface is rocky
and the vegetation is often disturbed, mostly by local farming practices
(cattle and sheep).
75
The characteristic species are listed in species group T (Table 3.1) with
Eragrostis curvula the only species with a noteworthy occurrence. The tree,
Diospyros . Iycioides (species group l), is conspicuous and completely
dominates the vegetation (Table 3.1).
3.3.3 Cheilanthes ecktoniene- Tragus koelerioides Sub-community
A community restricted to the midslopes of south-facing hills with an
abundance of dolerite and sandstone rocks (> 2 m in diameter). The habitat
is more disturbed than the habitat associated with Eragrostis curvula-Sutera
albiflora Sub-community.
Tragus koelerioides, a common grass species in disturb and overgrazed
areas and the forb Oxalis depressa (species group U) are restricted to the
shady patches between big dolerite and sandstone boulders. The woody
component is inconspicuous and only the trees, Diospyros Iycioides (species
group Z), and Olea europaea subsp. africana (species group AB), as well as
the shrubs, Rhus erosa and Diospyros austro-africana (species group Z) and
R. burchellii (species group AB) occur. Besides Tragus koelerioides,
Themeda triandra (species group AC) and Heteropogon contortus (species
group AB) are the only noteworthy graminoids present (Table 3.1).
3.3.4 Olea europaea-Melianthus comosus Sub-community
This is a very local and limited plant community occurring on moist clayish
soil of the midslopes. Big rocks are common, but no gravel or stones occur
on the soil surface.
Melianthus comosus is the most conspicuous among the five
differentiating species (species group V, Table 3.1). Diospyros Iycioides
(species group Z) is the most abundant tree species. This vegetation unit
differs markedly from the Cheilanthes ecktoniene- Tragus koeiertoides Sub-
community in the presence of Eragrostis lehmanniana (species group W),
76
the stronger presence of Diospyros /ycioides (species group Z) and the low
cover-abundance values of Olea europaea subsp. africana (species group
AB) and Themeda triandra (species group AC, Table 3.1).
3.3.5 Olea europaea-Wa/afrida saxatilis Sub-community
This vegetation unit is very limited, occurring only locally at very disturbed
patches of the midslopes of south-facing hills, south-west of Wepener. This
sub-community is not characterized by any diagnostic species group (Table
3.1). Rhus burchellii and Olea europaea subsp. africana (species group AB)
are the only two conspicuous woody species present. Grasses are scarce
and are restricted to Eragrostis /ehmanniana (species group W), Aristida
diffusa (species group AB) and Themeda triandra (species group AC, Table
3.1) .
3.4 A/oe ferox-Rhigozum obovatum Community
The A/oe ferox-Rhigozum obovatum Community is found on the moist
upland crests of steep (30°-60°) south- and south-east-facing slopes in the
south-eastern parts of the study area near the former Transkei border. The
vegetation of these dolerite hills is virtually undisturbed. However, patches
of overgrazing, particularly by rock dassies (Procavia capensis) occur.
A/oe ferox (species group Y) is the only exclusively diagnostic species
present with the shrubs, Rhigozum obovatum and Grewia occidenta/is, also
evident (species group Y, Table 3.1). According to Bornman & Hardy (1971)
A. ferox is distributed over a range of 1 000 kilometres from Swellendam in
the Western Cape to the southern parts of Lesotho and varies considerably
in its different localities. These aloe plants grow singly or in dense groups
and have t~1I stems up to 3 metres high (Bornman & Hardy 1971). The
present authors endorse their observations. Other wide distributed woody
species, besides R. obovatum and G. occidentalis, include the shrubs Felicia
fi/ifo/ia and Diospyros austro-africana (species group Z). The trees,
Diospyros /ycioides (species group Z), Olea europaea subsp. africana
77
(species group AB) and the shrubs, Rhus erosa (species group l) and R.
burchellii (species group AB) are inconspicuous. Hyparrhenia hirta (species
group M) and Themeda triandra (species group AC) are the abundant
grasses (Table 3.1). This vegetation unit shows affinities with the
Hyparrhenia hirta-Osyris lanceolata Community and Euclea crispa subsp.
crispa-Rhus dentata Community by the presence of Hyparrhenia hirta
(species group M, Table 3.1).
Two distinct units further divide this community (Table 3.1).
3.4.1 Aloe ferox-Setaria incrassata Sub-community
The Aloe ferox-Setaria incrassata Sub-community occur in well-drained
areas with big sanstone rocks covering 40-60% of the surface. The aspect
is mainly south-east. Overgrazing of the vegetation, especially by the rock
dassie is common.
The differential species are listed in species group X of which Setaria
incrassata and Ruschia hamata are the most abundant. Rhus erosa (species
group Z) is the most conspicuous woody species with Themeda triandra
(species group AC), Heteropogon contortus (species group AB) and
especially Hyparrhenia birte (species group M) the most prominent grasses
(Table 3.1).
3.4.2 Aloe ferox-Olea europaea Sub-community
This vegetation unit occurs on the well-drained areas on south-facing slopes
of hills. The habitat is drier than that of the Aloe ferox-Setaria incrassata
Sub-community.
This sub-community further differs from the Aloe ferox-Setaria incrassata
Sub-community in the absence of diagnostic species, the absence of
Diospyros Iycioides (species group Z) and Euclea crispa subsp. ovata
(species group AB), the higher cover-abundance of Hyparrhenia hirta
78
(species group M) and Aloe ferox (species group Y), as well as the lower
cover-abundances of the shrub Rhus erosa (species group Z) and the
grasses, Heteropogon contortus (species group AB) and Themeda triandra
(species group AC, Table 3.1).
3.5 Rhus ciliata-Olea europaea Community
The Rhus ciliata-Olea europaea Community is strongly associated with the
drier hills and ridges of the study area between Wepener and Zastron. The
aspects are mostly south to south-east on isolated dolerite hills and ridges.
The Ca land type is the most important and indicates land that Qualifies as a
plinthic catena with Hutton-, Bainsvlei-, Avalon- and Longlands soils the
most prominent (Land Type Survey Staff, in press).
The Rhus ciliata-Olea europaea Community is limited in distribution and
size and have only two differentiating species, Rhus ciliata and Euphorbia
mauritanica, of which only R. ciliata is abundant (species group AA). Olea
europees (species group AB) is the only conspicuous tree species with
Aristida congesta, A. diffusa (species group AB) and Themeda triandra
(species group AC) the most prominent grasses (Table 3.1).
3.6 Euclea crispa subsp. ovata-Olea europaea Community
Like the Rhus ciliata-Olea europaea Community, this vegetation unit is also
restricted to the drier hills and ridges of the study area. The aspect is south
to south-east. The Fb land type is most prominent and indicates land where
lime regularly occurs in the soil. Glenrosa, Mispah and Oakleaf soils are the
most abundant (Land Type Survey Staff, in press).
This is also a very limited vegetation unit with only a few species
present. Diagnostic species are absent. Euclea crispa subsp. ovata is the
only shrub present in abundance (species group AB, Table 3.1). This plant
community also lacks species of species group AA (Table 3.1) which
characterize the Rhus ciliata-Olea europaea Community. The shrubs Rhus
79
burchel/ii and Euclea crispa subsp. ovata (species group AB) are the only
other abundant woody representatives (Table 3.1).
ORDINATION
In the scatter diagram (Figure 2) the distribution of the relevés along the
first and second axes of the DECORANAordination is given. The distribution
of the different plant communities and sub-communities on the diagram
were not clear. It was thus decided to only include differences between the
different plant major communities. Major communities associated with
ravines in relatively wet conditions on Elliot Formations are situated to the
right of the diagram and relatively dry open woodland vegetation on Molteno
Sandstone to the left (axis 1). Along the second axis, the plant communities
with relatively low species diversity are situated at the bottom of the
diagram, while the plant communities with higher species diversity are
situated towards the top (Figure 2).
DISCUSSION
The aim of this study was to identify, characterize and ecologically interpret
the plant communities of the Zastron area in the southern Free State.
Although the Olea europaea-Rhus burchel/ii Major Community (major
community 3 ) are generally regarded as dry shrubland (Malan 1992, Malan
et al. 1995), these vegetation units also occur within the 600-800 mm
rainfall interval and are thus included in this manuscript.
The study area offers a wide variety of habitats and microclimates in a
limited area. All vegetation units in this study can be related to specific
environmental conditions and can therefore be ecologically distinguished and
interpreted.
The strong presence of woody species on many rocky outcrops in the
climatic climax Grassland Biome is ascribed to the shelter and favourable
80
moisture regimes associated with high percentages of surface and sub-
surface rock. Rainfall accumulation between rocks, concomitant with the
volume of the soil profile occupied by sub-surface rocks, results in deeper
rainfall infiltration, favouring species with. a taproot system. Equally
important may be the protection of seedlings and young plants by the rocks,
from frost and fire (Fuls 1993).
The most important woody species encountered include Buddleja
salviifolia, Diospyros austro-africana, D. Iycioides, Euclea crispa subsp.
ovata, Felicia filifolia, .Grewia occidentalis, Leucosidea sericea, Olea
europaea subsp. africana, Osyris lanceolata, Rhamnus prinoides, Rhus
burchellii, R. erosa and the exotic rose Rosa eglanteria. Cheilanthes
eckloniana is the most important fern and grows especially well in crevices
between rocks as well as on the plateaux. Abundant grasses are restricted
to Aristida diffusa, A. congesta, Heteropogon contortus, Hyparrhenia hirta
and Themeda triandra.
Leucosidea sericea and Buddleja saligna are also abundant in the moist
shrubland and forest communities of Korannaberg described by Du Preez
(1991 ).
According to Du Preez (1991), a geological feature that plays an
important role in the survival of the Afro-montane forest communities, is the
narrow ravines where dolerite dykes cut through the Clarens Formation at
the edge of the cliffs. During the intrusion phase (Jurassic Period), hot
igneous material penetrated the sandstone and baked it to hard solid rock,
which is resistant to weathering. The ravines developed by the subsequent
more rapid weathering of the dolerite dykes (Du Preez 1991). Yellow,
apedal, well-drained, oligotrophic soils are restricted to the plateaux.
Lithosols are found mainly on the talus slopes (Du Preez 1991).
Roberts (1966) mentions Afro-montane fynbos communities from Thaba
'Nchu mountain, but his classification is derived from an association
analvsls. which is not comparable to a Braun-Blanquet classification.
81
The presented delineation OT the plant communities and associated
habitats should be used as the basis for future management and
conservation of these areas.
Although the distribution of these plant communities is restricted to the
south-eastern corner of the southern Free State, there are distinct
similarities and differences between these species and communities and
those plant communities encountered in the drier part of the southern Free
State (Malan et al. 1995).
Due to the vulnerability of the vegetation in this area, special care should
be taken to protect it from destruction by fire, habitat disturbance by hikers,
especially on the Aasvoëlberg Mountain, and the collection of firewood. This
shrubland vegetation is of great importance for the conservation of wildlife.
Besides the providing of shelter for nume,rousmammals and bird species, it
also hosts important nesting sites for the endangered Cape Vulture (Gyps
coprotheres) .
82
3.5 REFERENCES
ACOCKS, J.P.H. 1953. Veld types of South Africa. Mem. bot. Surv. S. Afr.
28: 1-192.
ACOCKS, J. P. H. 1988. Veld types of South Africa, 3rd edn. Mem. bot.
Surv. S. Afr. 57: 1-146.
ARNOLD, T.H. & DE WET, B.C. 1993. Plants of southern Africa: names and
distribution. Mem. bot. Surv. S. Afr. 62: 1-825.
BEWS, J.W. 1917. The plant ecology of the Drakensberg Range. Ann. Nat.
Mus. 3: 511-565.
BORNMAN, H & HARDY, D. 1971. Aloes of the South African veld.
Voortrekker Press, Johannesburg.
BRAUN-BLANQUET, J. 1964. Pflanzensociologie. Springer Report, Wien.
COATES PALGRAVE, K. 1984. Trees of Southern Africa. 2 nd Revised edn.
Struik Publishers.
DINGLE, R.V., SIESER,W.G. & NEWTON, A.R. 1983. Mesozoic and tertiary
geology of southern Africa. A.A. Balkema, Rotterdam.
DU PREEZ, P.J. 1991. A syntaxonomical ánd synecological study of the
south-eastern Orange Free State and related areas with special reference
to Korannaberg. Unpublished Ph.D. dissertation. University of the Orange
Free State, Bloemfontein.
EDWARDS, D. 1967. A plant ecological survey of the Tugela River Basin,
Natal, Mem. bot. Surv. S. Afr. 36: 1.,.285.
FULS, E.R. 1993. Vegetation ecólogy of the northern Orange Free State.
Unpublished Ph.D. dissertation. University of Pretoria, Pretoria.
83
GIBBS RUSSELL, G.E., WATSON, l., KOEKEMOER, M., SMOOK, l.,
BARKER, N.P., ANDERSON, H.M. & DALLWITZ, M.J. 1990. Grasses of
southern Africa. Mem. bot Surv. S. Afr. 58: 1-437.
HILL, M.O. 1979 a. DECORANA - A Fortran program for detrended
correspondence analysis and reciprocal overgrazing. Cornel! University,
New York.
HILL, M.O. 1979 b. TWINSPAN - A Fortran program for arranging
multivariate data in an ordered two-way table by classification of the
individuals and attributes. Cornel! University, New York.
HILTON-TAYLOR, C. 1987. Phytogeography and origins of the Karoo flora.
In: The Karoo Biome: A preliminary synthesis - vegetation and history,
eds. R.M. Cowling & P.W. Roux, Part 2, pp. 70-95. S. Afr. nat. Sci.
Prog. Rep. No 142.
KILLICK, D.J.B. 1959. An account of the plant ecology of the Table
Mountain area of Pietermaritzburg', Natal. Mem. bot. Surv. S. A fr. 32: 1-
133.
KILLICK, D.J.B. 1963. An account of the plant ecology of the Cathedral
Peak area of the Natal Drakensberg. Mem. bot. Surv. S. Afr. 34: 1-178.
LAND TYPE SURVEY STAFF (IN PRESS). Land types of the maps 2924 -
Koffiefontein and 2926 - Bloemfontein. Mem. agric. nat. Resources S.
Afr. No. 14.
MALAN, P.W. 1992. PlantsosioJogie van die Bloemfontein-wes distrik.
Unpublished M.Sc. thesis, University of the Orange Free State,
Bloemfontein.
MALAN, P.W., VENTER, H.J.T. & DU PREEZ,P.J. 1995. Plant communities
of the western part of the Bloemfontein district: The Ca land type. S.
Afr. J. Bot. 61 (6): 306-311.
84
MENTIS, M.T. & HUNTLEY, B.J. 1982. A description of the Grassland
Biome Project. S. Afr. nat. Sci. Prog. Rep. 62: 1-129.
-
MUELLER-DOMBOIS, D. & ELLENBERG, H. 1974. Aims and Methods of
Vegetation Ecology. Wiley, New York.
POTGIETER, P.J. (ED.), lE ROUX, P.A.L., VAN su.Jon. J.J., VAN DER
RYST, C., KRIGE, S. & PRETORIUS,T. 1995. Regional overview study of
the Free State. Commissioned by the land and Agricultural POlicy
Centre, Bloemfontein.
ROBERTS, B.R. 1966. The ecology of Thaba 'Nchu. A statistical study of
vegetation/habitat relationships. Unpublished Ph.D. (Agric.) dissertation.
University of Natal. Pietermaritzburg.
SCHEEPERS,J.C. 1975. The plant ecology of the Kroonstad and Bethlehem
areas of the Highveld Agricultural Region.D.Sc. thesis, University of
Pretoria.
SCHEEPERS, J.C. 1986. Grassland. Biome Project: Proceedings of the
workshop on the classification and mapping. Ecosyst. Prog. Rep. 16: 1-
31.
STORY, R. 1952. A botanical survey of the Kleikammahoek District. Mem.
bot. Surv. S. Afr. 27: 1-181.
VAN OUDTSHOORN, F.P. 1991. Gids tot grasse van Suid-Afrika. Briza
Publications, Arcadia, Pretoria.
VENTER, H.J.T. & JOUBERT, A. M. 1985. Klimplante, bome en struike van
die Oranje-Vrystaat, 2nd edn., P.J. de Villiers, Bloemfontein.
WEST, O. 1951. The vegetation of the Weenen County, Natal. Mem. bot.
Surv. S. Afr. 23: 1-158. I
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WESTHOFF, V. 1971. The dynamic structure of plant communities in
relation to the objectives of conservation. In: Duffey, E. & Watt, A.S.,
1971. The scientific management of animal and plant communities for
conservation. BlackweIl, Oxford.
WHITTAKER, R. H. 1978. Classification of plant communities. W. Junk, The
Hague.
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86
CHAPTER 4
Vegetation ecology of the southern Free State
Vegetation ecology of the southern Free State: Dry shrubland
communities of the rocky outcrops
it Accepted: South African Journal of Botany
87
CHAPTER 4
Veqetation ecology of the southern Free State: Dry shrubland
communities of the rocky outcrops.
P.W. Malan .., H.J.T. Venter & P.J. du Preez
P.O. Box 292, Mafikeng, 2745
Keywords: Braun-Blanquet vegetation classification, DECORANA ordination,
habitat related, rocky outcrops, southern Free State, TWINSPAN .
.. To whom correspondence should be addressed.
ABSTRAcr
A phytosociological analysis of the vegetation of the rocky outcrops of the
southern Free State is presented. Relevés were compiled in 185 stratified
random sample plots. A TWINSPAN classification, refined by Braun-Blanquet
procedures, resulted in 35· plant communities. All these communities have
ecological similarities and differences as pointed out by the DCA ordination.
The described communities serve as a basis for their spatial distribution in
this area as well as for determining their conservation status in the face of
increasing development and agriculture.
88
4.1 INTRODUCTION
The Grassland Biome in South Africa is under heavy pressure from several
different forms of man induced activities (Du Preez 1991). To enable optimal
resource utilization and conservation, a vegetation classification program
has been implemented in the Grassland Biome (Mentis & Huntley 1982;
Scheepers 1987). This survey was planned to provide data for the
synecological synthesis of the Grassland Biome Project (Scheepers 1987).
Attempts to conserve biotic diversity are pointless and impossible if the
entities contributing to diversity are not known. Plant communities are
conceived as individual, recognizable entities (Coetzee et al. 1993) and are
characterised by their floristic composition (Whittaker 1978). Because the
natural vegetation of the rocky outcrops in the southern Free State are
clearly adversely affected by past and existing farming practices as well as
continuous urban development (Fuls 1993), a detailed study of these areas
is long overdue.
The main object of this study was, therefore, to classify, describe and
ecologically interpret the shrubland communities of the rocky outcrops in
the southern Free State. These data should be of importance for ecologically
sound resource management, planning as well as for the identification of
possible conservation areas, especially in the urban areas.
4.2 STUDY AREA
The area studied is situated in the southern Free State west of the 600-800
mm rainfall interval and is bounded by 24° 20' and 27° 00' E longitude and
29° 00' and 30° 50' S latitude. Plant communities east of the 600-800 mm
rainfall interval are discussed elsewhere (Malan et al. in press.). Towns
situated in the study area are (from north to south) Bloemfontein,
Petrusburg, Fauresmith, Wepener, Zastron and Bethulie (Figure 4.1). In this
area, wetlands are mostly represented by streams, rivers and vleis and are
mainly found in bottomland situations. The area covers approximately 26
000 km2. Permanently waterlogged soils are scarce and seasonally standing
89
water is mostly restricted to slow-draining watercourses and drainage
channels. Slow-draining streams are common owing to the flatness of the
terrain over most of the study area.
The rainfall is erratic, especially in the western part of the study area and
increases in an easterly direction from a 300-400 mm per annum rainfall
interval to a 600-800 mm per annum rainfall interval.
A detailed description of the study area and environmental attributes is
given elsewhere (Chapter 2).
4.3 METHODS
Relevés were compiled in 185 stratified random sample plots. Surveys were
done during the summer and late summer of 1993 and 1994. Stratification
was based on rainfall, topographical position (slope, crest and plateau), soil
form and geology. No care was taken to place sample plots in severely
degraded areas. Plot sizes were fixed at 100 m2 (Scheepers 1975). In each
sample plot a list of all species present were compiled and the cover-
abundance of each species noted using the Braun-Blanquet scale (Mueller-
Dombois & Ellenberg 1974). Taxa names conform to those of Arnold & De
Wet (1993). No distinctions were made between different subspecies
except for Euclea crispa subsp. crispa and Euclea crispa subsp. ovata.
According to Venter & Joubert (1985) the latter is mainly distributed
through the drier ridge veld of the southern Free State, while Euclea crispa
subsp. crispa is' common to abundant in the kloof forests and rocky habitat
in the moist areas in the southern Free State. This is confirmed by Malan et
al. (Submitted). Euclea crispa subsp. ovata is referred to as Euclea crispa
while Olea europaea subsp. africana is referred to as Olea europaea in the
text. All the reference specimens are housed at the Geo Potts Herbarium at
the University of the Orange Free State. Other relevant information such as
habitat disturbance, degradation of the vegetation, rockiness of the soil
surface and human impact on the habitat were also noted. Soil depth was
determined by driving a marked steel pin as deep as possible into the soil.
90
Two-way indicator species analysis (TWINSPAN) (Hill 1979 a) was
applied to the floristic data set in order to derive a first approximation of the
vegetation types of the area. Refinement was done by means of Braun-
Blanquet procedures (Bredenkamp et al. 1989). The floristic data set was
further subjected to an ordination algorithm (Hill 1979 b), to determine
habitat gradients and the relationship with environmental variables.
4.4 RESULTS AND DISCUSSION
The vegetation of the rocky outcrops of the study area generally has a low
species diversity (See Table 4.1), but" contains a variety of trees, shrubs,
herbs and forbs. The general vegetation of the rocky outcrops can be
classified as the Themeda triandra-Euclea crispa Shrubland. This vegetation
can be divided into two major communities, namely shrubland vegetation of
hills and ridges (Major community 1) and dwarf shrubland associated with
flat areas on the plateaux of hills (Major community 2).
The shrubland of the hills and ridges can further be divided into four
distinct vegetation types:
1.1 shrubland of ravines and south- and east-facing slopes;
1.2 shrubland of the drier north and west-facing slopes;
1.3 shrubland of the dry, overutilized and disturbed crests and plateaux; and
1.4 shrubland of low hills on north and west-facing slopes.
The most abundant woody species associated with the hills include Olea
europaea, Grewia occidentens (species group K, Table 4.1), Buddleja saligna
(species group O), Tarchonanthus cemphoretus (species group Z), Euclea
crispe, Rhus erose, Felicia lilifolia, Diospyros austro-africana, Ehretia rigida
(species group AF), Rhus burchellii, and R. cutete (species group AJ, Table
4.1 ).
The grasses, Digitaria eriantha (species group U) and Eustachys
paspaloides (species group T) frequently occur in open shrubland, but are
limited to the low shrubland vegetation. Graminoids such as Themede
91
triandra and Heteropogon contortus (species group AJ) are conspicuous
throughout the entire study area (Table 4.1).
Dwarf shrubland associated with flat areas on the plateaux of hills occurs
primarily under dry conditions, is virtually unprotected from wind erosion,
and is restricted to only a few shrubs and dwarf shrubs such as Rhus erosa,
R. ci/iata, Eberlanzia spinosa and Felicia muricata as well as the small fern,
Mohria caffrorum (Table 4.1).
The vegetation is classified into 35 distinct plant units (Table 4.1). The
hierarchical classification of the two major plant communities of the
shrublands of the rocky outcrops of the southern Free State is as follows:
1 Euclea crispa-Aristida diffusa Major Community.
1.1 Olea europaea-Buddleja saligna Community.
1.1.1 Crassula lanceolata-Buddleja saligna Sub-community.
1.1.2 Cussonia paniculata-Maytenus heterophylla Sub-community.
1.1.3 Diospyros Iycioides-Buddleja saligna Sub-community.
1.1.3.1 Turbina oenotheroides-Diospyros Iycioides Variant.
1.1.3.2 Cussonia paniculata-Diospyros Iycioides Variant.
1.1.3.3 Solanum coccineum-Rhus burchellii Variant.
1.1.3.4 Olea europaea-Diospyros Iycioides Variant.
1.1.3.5 Rhus lancea-Diospyros Iycioides Variant.
1.1.4 Rhus lancea-Buddleja saligna Sub-community.
1.1.4.1 Acacia karroo-Schinus molle Variant.
1.1.4.2 Rhus lancea-Olea europaea Variant.
1.1.4.3 Osyris lanceolata-Rhus lancea Variant.
1.1 .5 Osyris lanceolata-Olea europaea Sub-community.
1.1.6 Ziziphus mucronata-Olea europaea Sub-community.
1.1 .7 Olea europaea-Buddleja saligna Sub-community.
1.2 Buddleja saligna-Euclea crispa Community
1.2.1 Opuntia ficus-indica-Buddleja saligna Sub-community.
1.2.2 Hermannia bryoniifolia-Pavonia burchellii Sub-community.
1.2.3 May tenus polyacantha-Buddleja saligna Sub-community.
92
1.2.4 Pupalia /appacea-Lantana rugosa Sub-community.
1.2.5 A/oe broomii-Themeda triandra Sub-community.
1.2.6 Triraphis andropogonoides-Budd/eja saligna Sub-community.
1.2.7 Budd/eja sa/igna-Themeda triandra Sub-community.
1.3 Tarchonanthus camphoratus- Themeda triandra Community.
1.3.1 Digitaria eriantha- Tarchonanthus camphoratus Sub-community.
1.3.1.1 Hermannia vestita-Protasparagus capensis Variant.
1.3.1.2 Se/ago a/bida-Oxa/is cornicu/ata Variant.
1.3.1.3 Ughtfootia a/bens-Eustachys paspa/oides Variant.
1.3.2 He/ichrysum zeyheri-Themeda triandra Sub-community.
1.3.3 Euryops multitidus- Tarchonanthus camphoratus Sub-community.
1.3.4 Rhigozum aboveturn- Tarchonanthus camphoratus Sub-community.
1.3.4.1 Stipagrostis namaquensis-Rhigozum obovatum Variant.
1.3.4.2 Rhigoz,um obovatum-Heteropogon contortus Variant.
1.4 Euc/ea crisps- Themeda triandra Community.
1.4.1 Euc/ea crisps- Tragus berteronianus Sub-community.
1.4.2 Setaria sphace/ata-Rhus ciliata. Sub-community.
1.4.3 Phyllanthus parvu/us-Sesamum capense Sub-community.
1.4.4 Kleinie /ongifolia- Themeda triandra Sub-community.
1.4.5 Cymbopogon excsvetus-ëuctee crispa Sub-community.
1.4.6 Euc/ea crispa-Aristida diffusa Sub-community.
2 Mohria eettrarum- Themeda triendrs Major-community.
2.1 Eberlanzia spinosa-Mohria caffrorum Community.
2.2 Felicia muricata-Mohria caffrorum Community.
DESCRIPTION OF THE COMMUNITIES
1 Euclea crispa-Aristida diffusa Major Community
This shrubland occurs mostly on the southerly and easterly facing slopes of
hills and ridges and also within ravines and drainage lines or depressions on
93
northerly facing slopes. These slopes are relatively undisturbed to mildly
disturbed and/or overgrazed.
The most common, often dominant, woody species encountered is
Euclea crispa (species group AF, Table 4.1). This species is widely
distributed on the rocky outcrops of the southern Free State (Venter &
Joubert 1985). According to the Tree Society of southern Africa (1969), E.
crispa is one of the most common trees throughout South Africa. The
shrubs, Rhus erosa and Diospyros austro-africana (species group AF) are
also frequently encountered. Rhus burchellii (species group AJ) is the most
common shrub in rocky ravines and on outcrops. Graminoids include
Aristida diffusa, Sporobolus fimbriatus, Cymbopogon plurinodis, Eragrostis
curvula, Elionurus muticus (species group AF), Themeda triandra, and
Heteropogon contortus (species group AJ, Table 4.1).
This shrubland is further divided into four distinct plant communities
(Table 4.1).
1. 1 Olea europaea-Buddleja saligna Community
This shrubland commonly occurs as scrub on rocky places and ravine areas.
The aspects are mostly southerly and easterly. The habitat is generally cool
due to the shading of overhanging cliffs, moist and undisturbed; Areas of
fine gravel, due to continuous erosion, give the soil a stony appearance.
This shrubland also occurs on the gradual footslopes of hills and ridges. The
soil here is generally deep (> 100 mm deep) and of the Avalon form with a
clay content of often higher than 35% (Macvicar et al. 1977).
Trees and shrubs are totally dominant within this plant community. The
differentiating species are listed in species group K (Table 4.1). Buddleja
saligna (species group Q) and Olea europaea (species group K) are the most
common tree species present. The most locally conspicuous shrub is Grewia
occidentalis (species group K) which has an average height of -c 3 m. This
species generally does not have a high cover-abundance, but is widely
distributed, especially in the dense ravine areas. Euclea crispa (species
94
group AF) frequently occurs and is sometimes very abundant in rocky
habitats. The shrub, Rhus burchellii (species group AJ), is also very
abundant (Table 4.1).
Amongst the graminoids, Themeda triandra (species group AJ), is by far
the most conspicuous. Other grasses which also commonly occur include
Heteropogon contortus in rocky habitats, Aristida congesta and Eragrostis
lehmanniana (species group AJ, Table 4.1) which are commonly associated
with overgrazed and disturbed habitats (Van Oudtshoorn 1991).
The semi-parasite, Viscum rotundifolium (species group K) is a
stemparasite which occurs most frequently on Acacia karroo, Buddleja
saligna and Ziziphus mucronata.
This vegetation unit comprises seven distinct sub-communities (Table
4.1 ).
1.1.1 Crassula lanceolata-Buddleja saligna Sub-community
This is a very limited plant community which is restricted to shady areas of
ravines at the footslopes of south-facing slopes. The soil is rocky and large
boulders (> 3 metres in diameter) occur randomly. Rock slabs virtually
cover the soil surface. The habitat is moist and cool with overhanging cliffs
causing minimum exposure to direct sunlight.
The small forb, Crassula lanceolata (species group A), characterizes this
sub-community (Table 4.1). Buddleja saligna (species group a) and Olea
europees (species group K) are the only conspicuous tree species. The small
fern, Mohria caffrorum (species group AI), which often grows luxuriously in
this rocky habitat, is also abundant. Shrubs are scarce and restricted to
Grewia occidentalis (species group K), Rhus burchellii and Protasparagus
laricinus (species group AJ, Table 4.1). Triraphis andropogonoides (species
group P) and Eragrostis lehmanniana (species group AJ) are the most
common graminoids present (Table 4.1).
95
An average of 12 species/relevé was recorded for this sub-community
(Table 4.1).
1.1.2 Cussonia panieu/a ta-Maytenus heterophylla Sub-community
This plant community is restricted to the upper half of south-facing slopes
where large dolerite boulders are common and the habitat is moist and cool.
The diagnostic species (species group B, Table 4.1) and Talinum eaffrum
especially grow randomly in clayish soil in the shade of large boulders
(generally > 2 metres in diameter).
This is a poorly developed plant community with all the differentiating
species having a low cover-abundance (species group B, Table 4.1). The
most, abundant woody species are Cussonia panieu/ata (species group D),
Buddleja saligna (species group Q), Olea europaea (species group K) and
Eue/ea erispa (species group AF). According to the Tree Society of southern
Africa (1969), C. panieulata commonly grows in the open, preferring dry
situations. This was not the case here as the habitat is cool and moist.
Themeda triandra and Heteropogon eontortus (species group AJ) are the
most common grass species (Table 4.1).
An average of 18 species/relevé was recorded for this sub-community
(Table 4.1).
1.1.3 Diospyros /yeioides-Budd/eja sa/igna Sub-community
This plant community is found on the middle and lower half of south-facing
slopes and within drainage lines or depressions of east-facing slopes. It is
also common in ravines and along water courses. The soil is generally
rocky, except along the water courses where clayish soil is abundant.
Diospyros Iyeioides (species group F) differentiates this vegetation unit.
According to Coates Palgrave (1984), D. /yeioides occurs in almost all types
of habitat and can reaches heights of up to 7 metres. The tree, Olea
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europaea (species group K) has a low cover-abundance value and often
reaches heights in excess of 5 metres. Buddleja saligna (species group a) is
very abundant, especially in the Cussonia paniculata-Diospyros Iycioides
Variant (Table 4.1). Euclea crispa .(species group AF) and Rhus burchellii
(species group AJ) are the most abundant shrubs present (Table 4.1).
Grasses are absent from this community with the exception of Themeda
triandra and Heteropogon contortus which have wide distributions (Table
4.1 ).
Five distinct vegetation units further characterize this sub-community
(Table 4.1).
1.1.3.1 Turbina oenotheroides-Diospyros Iycioides Variant
This variant is restricted to lower south-facing slopes. The habitat is
marginally less rocky than that of the Cussonia paniculata-Diospyros
Iycioides Variant and the soil is clayish. Runoff water from upslope causes
accumulation of water, especially in the low-lying areas so tat standing
water is visible for virtually weeks after good rains.
This variant is differentiated by the scanty occurrence of Turbina
oenotheroides (species group C). Conspicuous species are limited and
restricted to the woody species Cussonia paniculata (species group D),
Diospyros Iycioides (species group F), Buddleja saligna (species group a),
Euclea crispa, Rhus erosa (species group AF) and R. burchellii (species
group AJ).
An average of 11 species/relevé was recorded for this variant (Table
4.1 ).
97
1.1.3.2 Cussonia paniculata-Diospyros Iycioides Variant
This variant is restricted to the midslopes of south-facing slopes of hills and
ridges. The gradient is sometimes very steep (> 70°), but generally varies
between 20°-50° with a rock cover of 30-60 %.
The Cussonia paniculata-Diospyros tvcioides Variant lacks exclusive
diagnostic species with the absence of species from species groups A, B
and C also evident (Table 4.1). Cussonia paniculata (species group D),
generally not exceeding two metres in height, is widely distributed, but has
a low cover-abundance throughout the entire variant (Table 4.1). The high
cover-abundance of Buddlej'a saligna (species group 0) and Olea europaea
(species group K) is characteristic. The stemparasite Viscum rotundifolium
(species group K) is semi-parasitic and is associated with Olea europaea
(species group K) and Buddleja saligna (species group 0, Table 4.1). Other
less common woody species include Diospyros Iycioides (species group F), .
Grewia occidentalis (species group K) and Rhus burchellii (species group
AJ). Graminoids are scarce and are virtually restricted to Themeda triandra
(species group AJ, Table 4.1).
This variant recorded ali average of 13 species/relevé (Table 4.1).
1.1.3.3 Solanum coccineum-Rhus burchellii Variant
This vegetation unit is common on the midslopes of south-facing hills. The
soil surface is rocky with large boulders (> 2 metres in diameter) occurring.
Fine sandstone, due to continuous erosion of dolerite, is common and often
causes a slippery soil surface. Virtually the whole vegetation unit occurs in
the shade of Buddleja saligna and Olea europaea.
Exclusive diagnostic species are absent, but the vegetation unit is
differentiated by the constant presence of Solanum coccineum (species
group E, Table 4.1). Also conspicuous is the absence of species of species
groups A-D (Table 4.1). Abundant species are scarce with only the trees,
Olea europaea (species group K), Buddleja saligna (species group 0), the
~----------------------~------------------------------------------------------
98
shrub, Rhus burchellii (species group AJ) and Karoo encroacher,
Cbrvsocome ciliata (species group AJ), worth mentioning (Table 4.1). C.
ciliata, especially, is a sure sign of pasture degradation (See Chapter 7).
This variant recorded an average of 9 species/relevé (Table 4.1).
1.1.3.4 Olea europaea-Diospyros Iycioides Variant
This variant occurs on the lower half of slightly south-west-facing rocky
slopes. Large dolerite rocks (> 4 metres in diameter) occur on the soil
surface and the habitat is drier than the Solanum coccineum-Rhus burchellii
Variant.
This vegetation unit also lacks an exclusive diagnostic species group
(Table 4.1), but it is rather characterised by the absence of So/anum
coccineum (species group E) as well as a slightly higher cover-abundance of
Diospyros Iycioides (species group F). Prominent trees include Olea
europaea (species group K) and Diospyros /ycioides (species group F).
Among the shrubs, only Budd/eja sa/igna (species group Q), Euc/ea crispe,
Rhus erosa, Fe/icia ti/ito/ia, Diospyros eustro-etricsne (species group AF),
I
Rhus burchellii and Protasparagus suaveo/ens (species group AJ) are
conspicuous. Themeda triandra (species group AJ) is the only abundant
grass species (Table 4.1).
This variant recorded an average of 13 species/relevé (Table 4.1).
1.1.3.5 Rhus lancea-Diospyros Iycioides Variant
The Rhus lancea-Diospyros /ycioides Variant occurs mainly on the lower half
of the south-facing slopes slightly above drainage channels. The soil is very
shallow « 50 mm deep) and rocky with gravel and stones from upslope
covering the soil surface. No large dolerite boulders are visible on the soil
surface.
99
Diagnostic species are absent (Table 4.1). The constant presence of
Rhus lancea (species group H) is the most conspicuous difference between
this variant and the other sub-divisions of the Diospyros Iycioides-Buddleja
saligna Sub-community (Table 4.1). Buddleja saligna (species group a), Olea
europaea (species group K), Diospyros Iycioides (species group F) and Rhus
lancea (species group H) have high constancies with, D. Iycioides and R.
lancea less abundant (Table 4.1). Shrubs are scarce with Rhus erosa
(species group AF) and R. burchellii (species group AJ) being the most
common species present (Table 4.1).
This variant recorded an average of 12 species/relevé (Table 4.1).
1.1.4 Rhus lancea-Buddleja saligna Sub-community
This sub-community is encountered on gentle (5 °_20°) south-facing slopes
and in drainage channels with shallow soils « 150 mm deep). The soil is
less rocky than in the Diospyros Iycioides-Buddleja saligna Sub-community.
Fine gravel cover the soil surface.
Diagnostic species are absent, but the absence of Diospyros Iycioides
(species group F) in particular and the higher cover-abundance of Rhus
lancea (species group H) are noteworthy (Table 4.1).
The Rhus lancea-Buddleja saligna Sub-community comprises three
distinct variants (Table 4.1).
1.1 .4.1 Acacia karroo-Schinus molle Variant
The Acacia karroo-Schinus molle Variant is associated with the footslopes of
south-facing slopes in drainage channels. The soil is generally clayey and
covered by a thick layer (100-150 mm thick) of gravel and stones.
Acacia karroo, together with the exotic Schinus molle (species group G),
differentiate this variant (Table 4.1). According to Carr (1976), A. karroo is
100
more widely distributed than any of our other acacias (See Chapter 5). A.
karroo in the Free State is usually a single- or several-stemmed tree,
branching well clear of the ground to give a rounded outline and having a
height varying between 5 to 10 metres. A variant from the North-West is
generally similar when seen from a distance but tends to be somewhat
smaller (Carr 1976). Schinus molle is a hardy foreign tree from South
America that has become completely blended into the landscape of the more
arid areas (Venter & Joubert 1985).
Rhus lancea (species group H), Olea europees (species group K) and
Buddleja saligna (species group Q) dominate the vegetation. The only
abundant shrubs are Rhus burchellii and R. ciliata (species group AJ) with
Themeda triandra and Eragrostis lehmanniana (species group AJ) being the
most abundant graminoids (Table 4.1).
This variant recorded an average of 11 species/relevé (Table 4.1).
1.1.4.2 Rhus lancea-Olea europaea Variant
This vegetation unit is restricted to the gentle (5 °-1 0°) west-facing slopes.
The soil is shallow « 100 mm deep) and more rocky than in the Acacia
karroo-Schinus molle Variant. Fine gravel covers 60-80% of the soil surface.
This variant lacks exclusive diagnostic species. Acacia karroo and
Schinus molle, which differentiate the Acacia karroo-Schinus molle Variant,
are absent in this variant (Table 4.1). Rhus lancea (species group H) has a
wide distribution and generally exceeds 2 metres in height. Olea europaea
(species group K) and Rhus lancea (species group H) are the most common
tree species present. The shrubs, Buddlej'a saligna (species group Q), Rhus
erosa (species group AF) and R. burchellii (species group AJ) are not widely
dispersed but have high cover-abundances in certain areas (Table 4.1).
Themeda triandra (species group AJ) is the most important grass
encountered.
lal
An average of 9 species/relevé was recorded for the Rhus lancea-Olea
europaea Variant (Table 4.1).
1.1.4.3 Osyris lanceolata-Rhus lancea Variant
The Osyris lanceo/ata-Rhus lancea Variant is restricted to ravines of south-
facing footslopes. The habitat is more moist than that of the previous two
variants of the Rhus lancea-Buddleja saligna Sub-community. Large dolerite
boulders are common and provide perfect hiding places for the rock hyrax
(Procavia capensis) . The soil surface is trampled due to continuous
overgrazing by livestock.
This variant lacks exclusive diagnostic species, but the presence of
Osyris lanceolata differentiates it from the previous two variants of the
Rhus /ancea-Budd/eja saligna Sub-community (Table 4.1). According to the
Tree Society of southern Africa (1969), O. lanceolata is found growing on
rocky ridges, outcrops and hillsides amongst other species and is never
found in abundance in the W.itwatersrand. This was also the case here.
Rhus /ancea (species group H) and Olea europaea (species group K) are the
only other regularly occurring tree species present. Buddleja saligna (species
group a) and Rhus erosa (species group AF) are the most prominent shrubs.
Grasses are scarce with Elionurus muticus (species group AF), Themeda
triandra and Heteropogon contortus (species group AJ) being most common
(Table 4.1).
An average of 14 species per sample plot was recorded for this variant
(Table 4.1).
1 . 1.5 Osyris lanceolata-Olea europaea Sub-community
This plant community is encountered on the steeper (25°-50°) south-facing
slopes. The soil is generally rocky and shallow « 100 mm deep). Rock
sheets are frequently found and the average rock cover is 30-50%.
102
This sub-community has no diagnostic species but is characterised by
the presence of Osyris lanceolata (species group I) in the absence of Rhus
lancea (species group H). Olea europaea (species group K) and Osyris
lanceolata (species group I) are the most abundant tree species with the
shrubs Buddleja saligna (species group Q), Euclea crispa, Rhus erosa
(species group AF), R. burchellii and R. ei/iata (species group AJ) also being
conspicuous. Themeda triandra and Heteropogon contortus (species group
AJ) are the most abundant grasses.
An average of 13 species per sample plot was recorded for this sub--
community (Table 4.1).
1.1.6 Ziziphus mucronata-Olea europaea Sub-community
This sub-community is found on the steep (15°-50°), boulder-rich south-
facing slopes of hills. The soil surface is uneven and rocky.
The high constancy of Ziziphus mucronata (species group J) and Olea
europaea (species group K), as well as the concentrated occurrence of the
exotic Catoneester sp. (species group J), differentiate this sub-community
from the Osyris lanceolata-Olea europaea Sub-community (Table 4.1).
According to Coates Palgrave (1984), Z. inucronata occurs in a wide variety
of habitats, varying from open woodland to alluvial soils along rivers. It is-
also- said to indicate the presence of underground water (Coates Palgrave
1984).
Olea europaea (species group K) and Buddleja saligna (species group Q)
are conspicuous with Euclea crispe, Felicia fi/ifolia (species group AF), Rhus
burchellii, R. ciliata and Protasparagus laricinus (species group AJ) being the
most abundant shrubs. Grass species are scarce with Themeda triandra
(species group AJ) being the most common (Table 4.1).
The Ziziphus mucronata-Olea europaea Sub-community recorded an
average of 13 species per sample plot (Table 4.1).
103
1.1 .7 Olea europaea-Buddleja saligna Sub-community
This shrubland sub-community occurs randomly on hills and ridges in the
study area. The aspects are generally south, south-west and east. The soil
is rocky and shallow « 100 mm deep).
Characteristic of this widely distributed sub-community is the absence of
diagnostic species and the complete dominance of Olea europaea (species
group K) and Buddleja saligna (species group Q). This vegetation unit also
lacks species of species groups A to J (Table 4.1). This is an open
shrubland with few other woody species occurring. Tarchonanthus
camphoratus (species group Z), Euclea crispa, as well as the shrubs Rhus
erosa, Ehretia rigida , Felicia filifolia (species group AF), Rhus burchellii and
R. ciliata (species group AJ) are also prominent. The grass, Themeda
triandra (species group AJ), has a restricted dominance (Table 4.1).
The Olea europaea-Buddleja saligna Sub-community recorded an average
of 10 species per sample plot (Table 4.1).
1.2 Buddleja saligna-Euclea crispa Community
This plant community occurs on the drier north- and west-facing footslopes
and crests of hills and ridges. Overgrazing is a more common phenomenon
than in the Olea europaea-Buddleja saligna Community. In contrast to the
Olea europaea-Buddleja saligna Community, Olea europaea (species group K)
is virtually absent from this vegetation unit (Table 4.1).
Seven distinct vegetation units were distinguished (Table 4.1).
1.2.1 Opuntia ficus-indica-Buddleja saligna Sub-community
This sub-community is restricted to the crests of hills. The soil is generally
shallow « 100 mm deep) with large dolerite boulders and rock sheets
104
commonly occurring. The Opuntia ticus-indica-Budd/eja saligna Sub-
community is virtually completely exposed to direct sunlight and wind, with
the trees generally not exceeding 2 m in height.
The exotic Opuntia ticus-indice (species group K), introduced from the
U.S.A. (Coates Palgrave 1984) have become naturalised and are now
widespread and extremely troublesome in certain areas. The high cover-
abundance values for Budd/eja sa/igna (species group a) are characteristic.
These shrubs are small « 2 m high), but numerous. Euc/ea crispa (species
group AF) is the only other noteworthy tree species present. The grass,
Themeda triandra (species group AJ), dominates the lower stratum with
Fe/icia ti/ito/ia (species group AF) and Rhus ei/iata (species group AJ) being
the most prominent representatives of the shrub stratum (Table 4.1).
An average of 7 species per sample plot was recorded for this sub-
community (Table 4.1).
1.2.2 Hermannia bryoniifo/ia-Pavonia burchellii Sub-communitv
This infrequent sub-community occurs in shady spots on the north-facing
footslopes of hills. Large, round boulders virtually cover the soil surface. The
tree stratum is generally not higher than 2 metres. The vegetation is
overgrazed by livestock and the exposed soil surface is trampled.
The differentiating species listed in species group L (Table 4.1) mainly
occur in the shade of dolerite boulders, with Hermannia bryoniitolia and
Pavonia burchellii (species group L) being the most abundant (Table 4.1). It
further differs from the Opuntia ticus-indica-Budd/eja sa/igna Sub-community
in the absence of Opuntia ticus-indice (species group K). Senecio
consanguineus and Me/ianthus comosus are exclusive to this sub-
community where Budd/eja saligna (species group a) is rather inconspicuous
(Table 4.1). The locally dominant Rhus ciliata (species group AJ) is the only
shrub worth mentioning and Themeda triandra and Aristida congesta
(species group AJ) are the only abundant grasses (Table 4.1).
105
An average of 8 species/relevé was recorded for this sub-community
(Table 4.1).
1.2.3 Maytenus polyacantha-Buddleja saligna Sub-community
This vegetation represents an open scrub and occurs mainly on and around
the crests of rocky hills. Overgrazing is a common phenomenon and damage
to the vegetation particularly by the rock hyrax is evident. Maytenus
polyacantha (species group M) is often heavily utilized.
The most conspicuous woody species is Buddleja saligna (species group
Q) which has a high cover-abundance (Table 4.1). In the absence of species
from species group 0, May tenus polyacantha (species group M) is
diagnostic of the May tenus polyacantha-Buddleja saligna Sub-community.
Rhus burchellii (species group AJ) and to a lesser extent Diospyros Iycioides
(species group F) are the only other prominent woody species, with
Themeda triandra (species group AJ) the only dominant grass (Table 4.1).
Euclea crispa and Diospyros austro-africana (species group AF) occur locally
(Table 4.1).
An average of 10 species/relevé was recorded for this sub-community
(Table 4.1).
1.2.4 Pupalia lappacea-Lantana rugosa Sub-community
This sub-community mainly occurs on west-facing slopes of low hills in the
shade of trees. Generally the soil surface is rocky and covered with fine
gravel.
The Pupalia lappacea-Lantana rugosa Sub-community is characterised by
Grewia occidentalis {species group Kl in the presence of the differentiating
Pupalia lappacea, Lantana rugosa, Solanum retroflexum, Chenopodium
ambrosioides, C. album, Schkuhria pinnata, Hibiscus trionum, the grass
Setaria verticil/ata and Commelina benghalensis {species group Nl. These
106
forbs are indicating continuous habitat disturbance. Buddleja saligna (species
group a), Grewia occidenta/is (species group K) and Rhus burchellii (species
group AJ) are the most common and widely distributed woody species.
Among the grasses Eustachys paspa/oides (species group T) and Sporobolus
fimbriatus (species group AF) are abundant. Themeda triandra (species
group AJ) is conspicuously absent. The small fern, Pellaea ca/ome/anos
(species group AJ) occurs, with a high constancy, in the crevices between
rocks.
An average of 18 species/relevé was recorded for this sub-community
(Table 4.1).
1.2.5 A/oe broomii- Themeda triandra Sub-community
The A/oe broomii- Themeda triandra Sub-community. occurs on north-
easterly-facing slopes and ravines with gradients varying from 8°-25°.
Large dolerite boulders and rock sheets are abundant. In the lower-lying
areas, weathered sandstone and gravel are common. The soil surface is
disturbed by trampling of livestock.
A/oe broomii, commonly known as "Bergaalwyn" or "Slangaalwyn" ,
Indigofera sessilifolia and Nenax microphvlle (species group 0) differentiate
this sub-community (Table 4.1). According to Jeppe (1974), A. broomli got
its native name "Slangaalwyn" because of the developing racemes
resembling a cobra-like snake. A. broomli is found from Prieska in the
Northern Cape to Luckhoff in the western Free State where it grows well in
soil with a high lime content and flourishes best in low rainfall areas with
frost in winter (Bornman & Hardy 1971.). Woody species are scarce with
only May tenus po/yacantha (species group M), Budd/eja sa/igna (species
group A), Euc/ea crispa and Rhus erosa (species group AF) common.
Themeda triandra (species. group AJ) is the only prominent grass species
with Digitaria eriantha (species group U), Sporobo/us fimbriatus,
Cymbopogon plurinodis, Eragrostis curvu/a (species group AF) and
Heteropogon contortus (species group AJ) less abundant. The forb, Stachys
107
rugosa (species group AJ), is commonly found growing in the crevices
between the dolerite rocks.
The A/oe broomii- Themeda triandra Sub-community recorded an average
of 16 species per sample plot (Table 4.1).
1.2.6 Triraphis andropogonoides-Budd/eja sa/igna Sub-community
This sub-community is encountered on north-facing slopes of less than 10°
and ravines where the soil is well-drained and 60-70% of the surface is
covered by rock sheets. No large boulders occur.
The constant occurrence of the grass, Triraphis andropogonoides
(specles group P) differentiates this sub-community (Table 4.1). According
to Van Oudtshoorn (1991), T. andropogonoides is unpalatable and
commonly occurs. in open grasslands on rocky hills. Budd/eja saligna
(species group a), Euc/ea crispa (species group AF) and Rhus burchellii
(species group AJ) are the most important woody species present with R.
ciliata (species group AJ) being the most locally abundant shrub, particularly
at the footslopes. The only other commonly occurring graminoids are
Themeda triandra, Heteropogon contortus and Eragrostis /ehmanniana
(species group AJ, Table 4.1).
The Triraphis andropogonoides-Budd/eja saligna Sub-community recorded
an average of 8 species per sample plot (Table 4.1).
1.2.7 Budd/eja saligna- Themeda triandra Sub-community
This widely distributed sub-community occurs mainly on the middle and
upper half of the northerly and westerly-facing slopes of the hills and
ridges. The gradient varies from 10-20°, with a rock cover of 20%-70%.
Large sandstone boulders are a common phenomenon, especially at the
edges of the overhanging cliffs.
108
This sub-community lacks diagnostic species and most of the species in
species groups A to P (Table 4.1). The only exceptions are the scanty
occurrences of Solanum coccineum (species group E), Pavonia burchellii
(species group L) and Hibiscus trionum (species group N, Table 4.1).
A shrub stratum is well developed with the woody species Buddleja
saligna (species group a), Euclea crispa (species group AF), Rhus burchellii
(species group AJ) and to a lesser extent Rhus erosa (species group AF)
being dominant. The small shrub, Rhus ciliata (species group AJ), is also
abundant, especially in the sheltered and moist environment provided by the
boulders. The hardy Protasparagus striatus (species group AF) is locally
common to abundant. Grasses are scarce with only Themeda triandra
(species group AJ) and Sporobolus fimbriatus (species group AF) being
conspicuous (Table 4.1).
An average of 8 species/relevé was recorded for this sub-community
(Table 4.1).
1.3 Tarchonanthus camphoratus- Themeda triandra Community
This plant community occurs on dry, overutilized crests and plateaux of hills
and ridges. Isolated patches of this shrubland occur on dry, disturbed,
westerly or northerly-facing slopes. Generally the habitat is less rocky than
in the Olea europaea-Buddleja saligna - and Buddleja saligna-Euclea crispa
Community. This shrubland is primarily characterised by the regular
occurrence of Tarchonanthus camphoratus (species group Z), a species that
is dominant over large areas of the scrub veld of the western Free State
(Venter & Joubert 1985).
In contrast to the shallow « 100 mm deep) soils of the Olea europaea-
Buddleja saligna- and Buddleja saligna-Euclea crispa Communities, the soils
associated with this community are often deep (> 300 mm deep). Duplex
soils with B-horizons are prominent on the slopes (Land Type Survey Staff,
in press) while calcareous soils occur in the low-lying areas and plains.
109
Four distinct sub-communities further characterize this plant community
(Table 4.1).
1.3.1 Digitaria eriantha- Tarchonanthus camphoratus Sub-community
This plant community is present on the plateaux of hills. Large dolerite
boulders occur in this community resulting in microhabitats with a moister
environment than surrounding areas. The soil varies from rocky to sandy
especially in the lower-lying areas.
In the presence of Tarchonanthus camphoratus, the occurrence of the
grass, Digitaria eriantha (species group U), differentiates this sub-community
(Table 4.1). Under normal circumstances this grass is regarded as indicative
of good pasture (Van Oudtshoorn 1991). Other abundant grasses include
Aristida diffusa, Sporobolus fimbriatus, Cymbopogon plurinodis (species
group AF) and Themeda triandra (species group AJ). Woody species are
limited and restricted to the trees Tarchonanthus camphoratus (species
group Z), Euclea crispa and the shrubs Rhus erosa (species group AF) and
Rhus burchellii (species group AJ), with Felicia fi/ifolia (species group AF)
being less abundant. The fern, Chei/anthes eckloniana (species group AF), is
also abundant, especially in micro-habitats between large boulders.
Three distinct variants further characterize this sub-community (Table
4.1).
1.3.1.1 Hermannia vestita-Protasparagus capensi's Variant
The habitat in which this limited variant occurs is generally dry and about
60% of the surface area covered by large round ish and sub-angular stones
and rocks between 0.1 and 0.5 m in diameter. Rock sheets are also found.
Although not diagnostic, this variant is characterised by the scanty
occurrences of Hermannia vestita and Protasparagus capensis (species
group R). Trees are scarce and are restricted to Tarchonanthus camphoratus
110
(species group Z) and Euclea crispa (species group AF). Shrubs present
include Rhus burchellii (species group AJ) and the dwarf shrub Felicia ti/ito/ia
(species group AF). The only conspicuous graminoids are Themeda triandra
and Heteropoqon contortus (species group AJ).
An average of 17 species/relevé was recorded for this variant (Table
4.1 ).
1.3.1.2 Se/ago a/bida-Oxa/is cornicu/ata Variant
This variant is associated with lowlands and less rocky soil than that of the
Hermannia vestita-Protasparagus capensis Variant. Sandy soils are more
common.·
The differentiating species of this vegetation unit (species group S, Table
4.1) have low cover-abundance values and are inconspicuous. The slightly
higher cover-abundance values of Digitaria eriantha (species group U),
Aristida diffusa, Rhus erosa, Sporobolus fimbriatus, Cymbopogon plurinodis,
the absence of Heteropogon contortus and Stachys rugosa (species group
AJ), as well as the dominance of Euclea crispa (species group AF),
characterize this variant (Table 4.1). The presence of the grass, Aristida
congesta and the Karoo encroacher, Chrysocoma ciliata (species group AJ),
also differentiates this community from the Hermannia vestita-Protasparagus
capensis Variant (Table 4.1). Walafrida saxatilis often grows in associatión
with Cbrvsocome ei/iata on sandy soils (See Chapter 7).
An average of 18 soecles/relevé was recorded for this variant (Table
4.1 ).
1.3.1.3 Lightfootia albens-Eustachys paspaloides Variant
This variant occurs mainly on rocky-sandy soil with fine gravel common on
the soil surface.
111
This variant lacks exclusively diagnostic species and is inconspicuous.
Except Tarchonanthus camphoratus, other woody species include Euclea
crispe, Rhus erosa, Felicia fi/ifolia (species group AF) and Rhus burchellii
(species group AJ). The fern, Cheilanthes eckloniana (species group AF) has
a higher cover-abundance here as in the Se/ago a/bida-Oxalis corniculata
Variant (Table 4.1). Abundant grasses are restricted to Themeda triandra
and Heteropogon contortus (species group AJ).
The Lightfootia albens-Eustachys paspa/oides Variant recorded an
average of 16 species/relevé (Table 4.1).
1.3.2 Helichrysum zeyheri- Themeda triandra Sub-community
The He/ichrysum zeyheri- Themeda triandra Sub-community is present on the
overutilized crests higher up on the north-facing slopes of hills. No boulders
occur, but the soil is rocky and shallow « 100 mm deep).
The differentiating species are listed in species group V, all of which
have a low cover-abundance (Table· 4.1) .. The tree, Tarchonanthus
camphoratus (species group Z), is conspicuous. T. camphoratus is shrublike,
generally not exceeding 2 m in height. A further characteristic of this
vegetation unit is. the dominance of Themeda triandra (species group AJ).
Heteropoqon contortus (species group AJ) is also abundant and is often
characteristic of rocky habitats (Van Oudtshoorn 1991).
The He/ichrysum zeyheri- Themeda triandra Sub-community recorded 14
species per sample plot (Table 4.1).
1.3.3 Euryops multifidus- Tarchonanthus camphoratus Sub-communitv
This sub-community is limited to the plateaux of hills with large rock plates
covering 60-70% the soil surface.
112
Euryops multifidus (species group W) differentiates this sub-community
(Table 4.1) and only a few other species occur. The tree Euclea crispa
(species group AF) and the small shrub Rhus ciliata are the most important
woody species. Grasses are virtually restricted to Themeda triandra (species
group AJ) and Aristida diffusa (species group AF, Table 4.1). Themeda
triandra has a restricted dominance, but is notably less abundant in this sub-
community than in the Helichrysum zeyheri- Themeda triandra Sub-
community (Table 4.1).
The Euryops multifidus- Tarchonanthus camphoratus Sub-community
recorded 7 species per sample plot (Table 4.1).
1.3.4 Rhigozum obovetum- Tarchonanthus camphoratus Sub-community
This sub-community mainly occurs on the dry overgrazed and often
trampled crests of north-facing slopes. The soil surface is rocky and covered
with large boulders.
The diagnostic shrub, Rhigozum obovatum (generally not higher than 2
m) (species group Y), is the most conspicuous shrub and often completely
dominates the vegetation. The tree, Tarchonanthus camphoratus (species
group Z), is the only other abundant woody species present (Table 4.1).
This sub-community is inconspicuous due to continuous overgrazing and the
occurrence of only a few species (Table 4.1). Noteworthy is the absence of
species in species group AF with the scanty occurrence of Ehretia rigida
being the only exception (Table 4.1).
Two variants further divide this sub-community (Table 4.1).
1.3.4.1 Stipagrostis namaquensis-Rhigozum obovatum Variant
This variant occurs on trampled ground, covered with a thick (100 mm
thick) layer of sand on north-facing slopes. Gravel and stones (50 mm or
less in diameter) cover 50% of the soil surface.
113
The grass, Stipagrostis namaquensis and the forb, Berkheya pinnatifida
(species group X) are diagnostic of this variant, but the dominant Rhigozum
obovatum .(species group Y) is more conspicuous. According to Coates
Palgrave (1984), R. obovatum commonly occurs in dry rocky places and
karroid scrub. R. obovatum is often heavily browsed on by game and stock
so that plants are frequently kept down to a height of about 1 m (Coates
Palgrave 1984). This was also the case here with the average height of R.
obovatum not exceeding 1 m. Kleinia longifolia (species group AD) has a
low cover-abundance in this variant, but is absent from the Rhigozum
obovatum-Heteropogon contortus Variant (Table 4.1).
The Stipagrostis namaquensis-Rhigozum obovatum Variant recorded an
average of 7 species/relevé (Table 4.1).
1.3.4.2 Rhigozum obovetum-Heteropoqon contortus Variant
This variant occurs in virtually the same habitat conditions than the
Stipagrostis namaquensis-Rhigozum obovatum Variant. Termite heaps are
conspicuous on the soil surface. The vegetation is overgrazed and the soil
surface trampled. The vegetation, especially Rhigozum obovatum, is much
smaller (not higher than 1 m) than in the Stipagrostis namaquensis-
Rhigozum obovatum Variant. Rhigozum obovatum also has a lower cover-
abundance than in the Stipagrostis namaquensis-Rhigozum obovatum
Variant (Table 4.1).
This variant lacks exclusive diagnostic species but is characterised by the
presence of Heteropogon contortus (species group AJ) which is absent in
the Stipagrostis nemequensis-Rniqozum obovatum Variant (Table 4.1). Also
conspicuous is the absence of Stipagrostis namaquensis and Berkheya
pinnatifida (species group X), diagnostic of the Stipagrostis namaquensis-
Rhigozum obovatum Variant (Table 4.1).
114
1.4 Euclea crispa- Themeda triandra Community
This plant community occurs on west, north and north-west facing slopes of
low hills in the central parts of the study area. The vegetation is often
severely overutilized by livestock and the herbaceous layer is often limited
or even completely destroyed. The slopes are mostly dry and warm due to
the high solar radiation associated with northerly facing slopes (Rossouw
1983). Surface rocks are predominantly doleritic with layers of sandstone
(often deeper than 150 mm) a common phenomenon on the footslopes.
This community lacks exclusive diagnostic species. Euclea crispa is the
only woody species present with high cover-abundance values (species
group AF, Table 4.1). The small shrub, Rhus ciliata (species group AJ), with
a random distribution has a restricted dominance especially in the more
rocky habitats.
Themeda triandra, Heteropogon contortus (species group AJ) and
Aristida diffusa (species group AF) are the grasses most often encountered.
Sporobotus. fimbriatus and Elionurus muticus and the small fern Cheilanthes
eckloniana (species group AF) have limited occurrences (Table 4.1).
This community is further divided into six distinct sub-communities
(Table 4.1).
1.4.1 Euclea crispa- Tragus berteronianus Sub-community
This sub-community is encountered on the dry north-facing slopes of
dolerite hills. The soil is rocky with stones covering 20-40% of the soil
surface.
The small grass, Tragus berteronianus (species group AA), differentiates
this sub-community, with the < 2 m hig_h"shrubby" tree, Euclea crispa
(species group AF) being the most abundant woody species. According to
Van Oudtshoorn (1991), T. berteronianus is unpalatable to livestock and it is
an indicator of degrading veld conditions. Euclea crispa (species group AF)
115
is the most important woody species present. Themeda triandra and
Heteropogon contortus (species group AJ) are the only commonly
encountered grasses. The dwarf fern, Cheilanthes eckloniana (species group
AF), has a patchy occurrence and is mostly restricted to crevices between
rocks.
The Euclea ertspo- Tragus berteronianus Sub-community recorded an
average of 10 species/relevé (Table 4.1).
1.4.2 Setaria sphacelata-Rhus ei/iata Sub-community
The Setaria sphacelata-Rhus ciliata Sub-community is also associated with
north-facing slopes, but the habitat is cooler and standing water in the low-
lying areas occurs for virtually weeks after good rains. The soil is less rocky
with the clay content generally exceeding 40% (Land Type Survey Staff, In
press) .
Setaria sphacelata (species group AB) differentiates this vegetation unit.
The absence of the small fern, Chei/anthes eckloniana, mentioned in the
Euclea crispe- Tragus' berteronianus Sub-community, the lower. cover-
abundance of Heteropogon contortus (species group AJ) as well as the
presence of the dwarf shrub, Rhus ciliata (species group AJ), further
differentiate this community. Themeda triandra (species group AJ) is the
only other noteworthy grass (Table 4.1).
An average of 9 species/relevé was recorded for this sub-community
(Table 4.1).
1.4.3 Phyllanthus parvulus-Sesamum capense Sub-community
The habitat conditions for this limited sub-community are virtually the same
as for the Setaria sphacelata-Rhus ciliata Sub-community. The soil surface is
covered with gravel and thus appears to have a more rocky surface.
116
Setaria sphacelata is absent from this plant community (Table 4.1) and
the differentiating species are listed in species group AC (Table 4.1), all of
which have a low cover-abundance value (Table 4.1). As with the Setaria
sphecetets-Rhus ci/iata Sub-community, Euclea crispa and Rhus ci/iata are
also abundant, but Themeda triandra (species group AJ) is less conspicuous
(Table 4.1). E. crispa (species group AF) often forms dense stands. Besides
T. triandra, other grasses such as Aristida diffusa, Sporobolus fimbriatus
and Elionurus muticus (species group AF) are also present, but are
inconspicuous (Table 4.1).
An average of 12 species/relevé was recorded for this sub-community
(Tale 4.1).
1.4.4 Kleinia longifolia- Themeda triandra Sub-community
The distribution of this sub-community is restricted to the lower half of the
north and west-facing rocky slopes. The soil surface is severely trampled
and overgrazing is common. The soil is sandy and deep (> 300 mm deep).
This sub-community lacks exclusive diagnostic species but is rather
characterised by the marginally greater frequency of Kleinia longifolia
(species group AD) than in the Phyllanthus parvulus-Sesamum capense Sub-
community. Although K. longifolia is regarded as highly unpalatable, it is
often utilized by livestock, especially during the winter months (Vahrmeijer
1981). According to Vahrmeijer (1981) this species is extremely toxic,
especially to horses and cattle. Other abundant species present include
Euclea crispa (species group AF), Themeda triandra, Rhus ei/iata and
Protasparagus laricinus (species group AJ, Table 4.1).
The Kleinia longifolia- Themeda triandra Sub-community recorded an
average of only 8 species/relevé (Table 4.1).
117
1.4.5 Cymbopogon excavatus-EtJclea crispa Sub-community
The Cymbopogon excavatus-Euclea crispa Sub-community is encountered
on the upper half of the westerly-facing slopes. The habitat is more rocky
than in the Phyllanthus parvulus-Sesamum capense- and Kleinia longifolia-
Themeda triandra Sub-communities. Large boulders are common, but no
gravel is visible on the soil surface.
The grass, Cymbopogon excavatus (species group AE), is the only
differentiating species (Table 4.1). The higher cover-abundance values of
the grass, Aristida diffusa (species group AF), in this sub-community are
also noteworthy (Table 4.1). Other grasses present include Sporobolus
fimbriatus (species group AF), Themeda triandra and Heteropogon contortus
(species group AJ). Euclea crispa (species group AF) is the most important
tree encountered. The most important shrubs include Rhus burchellii and R.
ciliata (species group AJ) with the dwarf shrub, Protasparagus striatus
(species group AF), having a restricted dominance (species group AF, Table
4.1).
An average of 10 species/relevé was recorded for this sub-community
(Table 4.1).
1.4.6 Euclea crispa-Aristida diffusa Sub-community
The Euclea crispa-Aristida diffusa Sub-community is found on clearly
disturbed (at least in patches), dry north-west facing slopes.
This sub-community lacks diagnostic species as well as species which
were encountered in all the sub-communities of the Euclea crispe- Themeda
triandra Community. This is mainly a shrubby-grassland community with
Euclea crispa (species group AF) the only important tree and Rhus ciliata
(species group AJ) being the only abundant shrub. Among the grasses,
Aristida diffusa (species group AF), Themeda triandra and Heteropogon
contortus (species group AJ) are abundant. Other grass species present
118
include Sporobolus fimbriatus and Enneapogon scoparius (species group AF,
Table 4.1).
An average of 9 species/relevé was recorded for this sub-community
(Table 4.1).
2 Mohria caffrorum- Themeda triandra Major-community
This major-community is predominantly associated with the flat areas on the
ridges and hill plateaux. The habitat is generally dry and virtually
unprotected from wind. The soil is shallow « 100 mm deep) and rock slabs
cover 60-80 % of the soil surface. The soil has a sandy-gravelly texture
with dolerite stones visible on the surface.
The Mohria caffrorum- Themeda triandra Major-community is
differentiated by the small fern, Mohria caffrorum (species group AI, Table
4.1). It is also differentiated by the limited occurrence of large trees and
shrubs.
This community divides into two distinct units (Table 4.1).
2.1 Eberlanzia spinosa-Mohria caffrorum Community
This plant community is encountered on the dry plateaux of rocky hills and
ridges, which often show signs of degradation due to continuous over
utilization by livestock. The soil is very shallow (often < 50 mm deep) and
rocky. Rock slabs cover 70-80 % of the soil surface and exposed soil is
limited.
The thorny succulent, Eberlanzia spinosa (species group AG), is the only
differentiating species for this sub-community but the fern, Mohria
caffrorum (species group AI), completely dominates the vegetation. Other
species with a limited distribution are the shrub, Rhigozum obovatum
119
(species group Y), the grass, Heteropogon contortus and the Karoo-
encroacher, Chrysocoma ciliata (species group AJ, Table 4.1).
2.2 Felicia muricata-Mohria caffrorum Community
The Felicia muricata-Mohria caffrorum Community is restricted to the more
disturbed areas the crests of hills and on plateaux. The soil is less rocky
than for the Eberlanzia spinosa-Mohria caffrorum Community and is often
sandy. Fine gravel covers the soil surface.
Felicia muricata (species group AH) differentiates this community. Mohria
caffrorum (species group AI) is also common, but far less dominant than in
the Eberlanzia spinosa-Mohria caffrorum Community, while the grass,
Themeda triandra, is more abundant within this community (Table 4.1).
Rhus ciliata (species group AJ) is locally dominant and the grass Aristida
congesta (species group AJ) is further" indicative of the disturbed condition
of this community.
ORDINATION
A DCA ordination of the relevés is given in Figure 4.2. The two major
communities described here have noteworthy similarities and differences.
The Eberlanzia spinosa - Mohria caffrorum - and Felicia muricata - Mohria
caffrorum Community of the Mohria caffrorum - Themeda triandra Major-
community (indicated bye and f respectively in the scatter diagram) are
virtually restricted to the high-lying areas on crests and plateaux while the
Euclea crispa - Aristida diffusa Major Community is restricted to the
footslopes of hills, ravines and crests (Axis 1, Figure 4.2). No clear
discontinuity is associated with axis 2 of the diagram (Figure 4.2).
120
DISCUSSION
The two major plant communities were all restricted to specific areas within
the study area. In most cases, the ordination illustrates the similarities
between the plant communities described. The vegetation of the rocky
outcrops is in a state of continuous degradation because of relatively low
rainfall for the last number of years, as well as the continuous over-
utilization by livestock. This is in contrast to the findings of Stuart-Hili et al.
(1984) in the climatic climax Grassland Biome where a strong presence of
woody species on the rocky outcrops was recorded. According to Stuart-Hili
et al. (1984) and Fuls (1993) the strong presence of woody species is
ascribed to favourable moisture regimes associated with high percentages of
surface rocks and rocks in the soil profile. Rainfall accumulation between
rocks, concomitant with the volume of the soil profile occupied by sub-
surface rocks, results in deeper rainfall infiltration, favouring species with a
taproot system (Fuls et al. 1993).
The most important species associated with the rocky outcrops in the
southern Free State include the woody species Olea europees, Buddleja
-saligna, Euclea crispa subsp. ovata, Rhus erosa, Felicia filifolia, Rhus
burchel/ii, R. ciliata, Protasparagus laricinus, P. suaveolens as well as the
grasses Themeda trlandra and Heteropogon contortus. Other woody species
with restricted distribution include Cussonia paniculata, Diospyros Iycioides,
Rhus lancea, Osyris lanceolata and Tarchonanthus camphoratus.
Generally the south-facing slopes have a higher species diversity than the
north-facing slopes. This is in accordance with Du Preez (1991), Eckhardt
(1993), Kooij (1990),' Malan (1992) and Fuls (1993). This is because of the
warmer micro-climate of the northerly facing slopes (Rossouw 1983, Fuls
1993). According to Eckhardt (1993), aspect and topography and
associated moisture regime are the overriding factors controlling the
distribution of the thicket and woodland vegetation of the north-eastern Free
State. This is also the case in the southern Free State as indicated in the
ordination (Figure 4.2).
1 __
121
The restricted distribution of the majority of the plant communities
associated with rocky outcrops, makes it imperative that conservation of
these plant communities receive high priority. Future research will'
concentrate on the conservation status of these species and the shrubland
communities of the southern Free State. This delineation of the plant
communities and associated habitats of the rocky outcrops of the southern
Free State should be used as the basis for future management and
conservation of these areas. The restricted distribution of the majority of the
plant communities associated with rocky outcrops, together with the low
species diversity, resulted from degradation, makes it imperative that these
areas receive high conservation priority.
122
4.5 REFERENCES
ARNOLD, T.H. & DE WET, B.C. 1993. Plants of southern Africa: names and
distribution. Mem. bot. Surv. S. Afr. 62: 1-825.
BORNMAN, H. & HARDY, D. 1971. Aloes of the South African veld.
Voortrekker Press, Johannesburg.
\ . BREDENKAMP, G.J., JOUBERT, A.F. & BEZUIDENHOUT, H. 1989. A
reconnaissance survey of the vegetation of the plains in the
Potchefstroom-Fochville-Parys area. S. Afr. J. Bot. 55 (2): 199-206.
CARR, J.D. 1976. The South African Acacias. Conservation press (PTV.)
LTD. Johannesburg.
COATES PALGRAVE, K. 1984. Trees of Southern Africa. 2 nd Revised edn.
Struik Publishers.
COETZEE, J.P., BREDENKAMP, G.J. AND VAN ROOYEN, N. 1993. The
Sub-humid Warm Temperate Mountain Bushveld plant communities of
the Pretoria-Witbank-Heidelberg area. S. Afr. J. Bot. 59(6): 623-632.
DU PREEZ, P.J. 1991. A syntaxonomical and svnecolcqlcal study of the
vegetation of the south-eastern Orange Free State and related areas with
special reference to Korannaberg. Ph.D. dissertation, University of the
Orange Free State, Bloemfontein.
ECKHARDT, H.C. 1993. A synecological study of the vegetation of the
north-eastern Orange Free State. Unpublished M.Sc. thesis. University of
Pretoria, Pretoria.
FULS, E.R., BREDENKAMP, G.J. & VAN ROOYEN, N. 1993. Law thicket
communities of rocky outcrops in the northern Orange Free State. S. Afr.
J. Bot. 59 (4): 360-369.
123
FULS, E.R. 1993. Vegetation ecology of the northern Orange Free State.
Unpublished Ph.D. dissertation. University of Pretoria, Pretoria.
HILL, M.O. 1979 a. TWINSPAN - a FORTRAN program arranging
multivariate data in an ordered two-way table by classification of
individuals and attributes. Cornell University, Ithaca, New York.
HILL, M.O. 1979 b. DECORANA - a FORTRAN program for detrended
correspondence analysis and reciprocal averaging. Department of
Ecology and Systematics, Cornell University, Ithaca, New York.
JEPPE, B. 1974. South African Aloes. 2 nd edn. Purnell & Sons. Cape
Town.
KOOIJ, M.S. 1990. A phytosociolbgical survey of the vegetation of the
north-western Orange Free State. Unpublished M.Sc. thesis University of
Pretoria, Pretoria.
LAND TYPE SURVEY STAFF (IN PRESS). Land types of the maps 2924 -
Koffiefontein and 2926 - Bloemfontein. Mem. agric. nat. Resources S.
Afr. No. 14.
MACVICAR, C.N., LOXTON, R.F., LAMBRECHTS, J.J.N., LE ROUX, J., DE
VILLIERS, J.M., VERSTER, E., MERRYWEATHER, F.R., VAN ROOYEN,
T.H. & HARMSE, ·H.J. VON M.· 1977. Grondklassifikasie, 'n Binomiese
sisteem vir Suid-Afrika. Govt. Printer, Pretoria.
MALAN, P.W. 1992. Plantsosiolagie van die Bloemfontein-wes distrik.
Unpublished M.Sc. thesis, University of the Orange Free State,
Bloemfontein.
MALAN, P.W., VENTER, H.J.T. & DU PREEZ,P.J. Vegetation ecology of the
southern Free State: Plant communities of the Zastron Area. S. Afr. J.
.Bot. (Submitted).
124
MENTIS, M.T. & HUNTLEY, B.J. 1982. A description of the Grassland
Biome Project. S. Atr. Nat. Scient. Prog. Rep. No. 62 pp. 29.
MUELLER-DOMBOIS, D. & ELLENBERG, H. 1974. Aims and Methods of
Vegetation Ecology. Wiley, New York.
ROSSOUW, L.F. 1983. 'n Ekologiese studie van die boomgemeenskappe
van die Bloemfonteinomgewing, Oranje-Vrystaat. M.Sc. thesis, University
of the Orange Free State.
SCHEEPERS,J.C. 1975. The plant ecology of the Kroonstad and Bethlehem
areas of the Highveld Agricultural Region. D.Sc. thesis, University of
Pretoria, Pretoria.
SCHEEPERS, J.C. 1987. Grassland Biome Project: Proceedings of the
workshop on the classification and mapping. S. Atr. Ecosys. Prog. Dec.
Rep. Series 16: 1-31.
STUART-HILL, G., TAINTON, G.C., AUCAMP, A.J. & DANCKWERTS, J.E.
1984. Infiltration and water use patterns in semi-arid South African
Savanna. Proc. 2nd Int. Rang!. CongoAdelaide.
TREE SOCIETY OF SOUTHERN AFRICA. 1969. Trees and shrubs of the
Witwatersrand. Witwatersrand University Press, Johannesburg.
VAHRMEIJER, J. 1981. Gifplante van Suider-Afrika wat veeverliese
veroorsaak. Table Mountain Publishers Ltd.
VAN OUDTSHOORN, F.P. 1991. Gids tot grasse van Suid-Afrika. Briza
Publications, Arcadia, Pretoria.
VENTER, H.J.T. & JOUBERT, A.M. 1985. Klimplante, bome en struike van
die Oranje-Vrystaat, 2nd edn., P.J. de Villiers, Bloemfontein.
WHITTAKER, R.H. 1978. Classification of plant communities. W. Junk, The
Hague.
125
CHAPTER 5
Vegetation ecology of the southern Free State
Acacia and related shrub communities of the dry south-western Free
State
126
CHAPTER 5
Acacia and related shrub communities of the dry south-western Free
State
5.1 INTRODUCTION
Mentis & Huntley (1982) stated the necessity to determine the location and
extent of the major vegetation types within the Grassland Biome. In this
context the vegetation of the southern and south-western Free State was
studied as part of the phytosociological research programme on the synthesis
of the vegetation of the western Grassland Biome in South Africa
(Bredenkamp et al. 1989; Bezuidenhout & Bredenkamp 1990; Kooij et al.
1990).
Plant communities are conceived as vegetation units that are characterized
by their floristic composition (Whittaker 1978). Each plant community may
thus be regarded as an unique entity with its own species composition and
associated set of environmental factors. According to Westhoff (1971) the
description of plant communities is essential to provide a scientific inventory
for conservation and in general for the presentation of biotic diversity.
The aim of this study is to classify and ecologically interpret the Acacia
communities in the arid south-western Free State by means of Braun-Blanquet
procedures. Acacias are such a conspicuous. feature of much of our
vegetation that there is much demand for information about them (Carr
1976). According to Carr (1976), the genus Acacia is one of the most
widespread and important genera in Africa. It was thus decided to describe
. .
the thornveld communities as a separate entity of the south-western Free
State. Shrubland communities of the rocky outcrops (Chapter 4), the drainage
channels (Chapter 6) and those communities associated with the high rainfall
region (600-800 mm rainfall region) within the southern and south-western
Free State (Chapter 3) are discussed elsewhere in this dissertation. This
manuscript will contribute towards the final objective of compiling a
synecological synthesis of the Grassland Biome Project (Scheepers 1986).
127
5.2 STUDY AREA
The study area (Figure 5.1) is part of the Nama-Karoo Biome (Rutherford .&
Westfall 1994) and falls within the 300-400 mm/annum rainfall interval
(Weather Bureau 1965) and includes the Orange River Broken Veld (Veld
Types 35, 36 and 40 respectively of Acocks 1988) and the Orange River
Nama Karoo (Hoffman 1996).
The main stratigraphic unit is the Ecca Group (SACS 1980). Alluvium,
sand and calcrete deposits also occur and are mainly situated in the north-
western corner of the study area, south-west of Jacobsdal, as well as in the
region of Luckhoff in the extreme south-western parts. Dolerite dykes
frequently occur, especially in the region of the Vanderkloof Dam (Du Toit
1954).
SOILS
The most common soil group is lime rich and weakly developed on rock of the
Kimberley and Plooysburg forms (Soil Classification Working Group 1991).
Other soil groups include sands, combinations of red clays and
undifferentiated rocks and lithosols. Many of the soil surfaces are easily
eroded by water and wind. Natural vegetation is mostly confined to shallow,
rocky, non-arable soils. According to Hoffman (1996) red and yellow apedal,
freely draining young soils are prominent in the largest part of the Orange
River Nama Karoo.
The Ae, Ag and Da land types are most prominent in the northern and
western parts of the study area. These soils are mainly red with a high base
status, (Ae and Ag land types). Duplex soils (clayish soils with a sandy layer
on top) with red B-horizons also occur (Da land type). In the southern parts of
the study area, the soil surface is more rocky, exposed rock covering 60-80%
of the surface (lb land type). The latter. is prominent in the region of the
Vanderkloof Dam (Land Type Survey Staff, in press).
128
A detailed description of the physical environment of the study area is
presented elsewhere (Chapter 2).
5.3 METHODS
Relevés were compiled in 83 stratified random sample plots. Care was taken
to avoid sampling of severely degraded vegetation and excessively disturbed
areas. Rainfall was used as a first stratification of the study area with land
type for a more detailed stratification.
Plot sizes were fixed at 100 m2 which are in accordance with plot sizes
used by Scheepers (1975), Bredenkamp & Theron (1978), Rossouw (1983),
Van Wyk (1983), MOller (1986), Du Preez (1991), Bezuidenhout (1993) and
Fuls (1993). For every plant species present in the sample plot, a cover-
abundance value was estimated according to the Braun-Blanquet scale
(Mueller-Dombois & Ellenberg 1974).
Two-way indicator species analysts (TWINSPAN) (Hill 1979 a) was applied
to the floristic data set in order to derive a first approximation of the plant
communities of the area. In order to determine vegetation gradients and the
relationship with environmental variables, Detrended Correspondence Analysis
(DECORANA) (Hill 1979 b) was applied to the floristic data set.
Taxon and author names comply with those of Arnold & De Wet (1993).
5.4 RESULTSAND DISCUSSION·
The vegetation of the study area separates into distinct plant communities.
The variation in topography creates a variety of habitats which in turn bear
different plant communities. Different utilization patterns also contribute to
this variety of communities. The hierarchical classification is as follows:
1 Tarchonanthus camphoratus-Acacia mellifera Major Community
1.1 Acacia mellifera-Scmidtia pappophoroides Community
129
1.2 Acacia mellifera-Hermannia comosa Community
1.3 Rhus burche/lii-Lantana rugosa Community
1.4 Barleria rigida-Fingerhuthia africana Community'
1.4.1 Justicia cuneata-Barleria rigida Sub-community
1.4.2 Barleria rigida-Eriocephalus spineseens Sub-community
1.5 Melhania rehmannii-Justicia protracta Community
1.5.1 Melhania rehmannii-Justicia cuneata Sub-community
1.5.2 Melhania rehmannii-Acacia melfifera Sub-community'
1.6 Cenchrus ci/iaris-Hermannia vestita Community
2 Grewia flava-Cenchrus ciliaris Major Community
2.1 Grewia flava-Fingerhuthia africana Community
2.2 Cenchrus ciliaris-Helichrysum lineare Community
3 Acacia torti/is-Heteropogon contortus Major Community
3.1 Cheilanthes eckloniana- Tarchonanthus camphoratus Community
3.1.1 Protasparagus mucronatus-Rhus ciliata Sub-community
3.1.2 Cheilanthes eckloniana-Eragrostis echinochloidea Sub-community
3.2 Acacia tortilis-Mevtenus polyacantha Community
3.2.1 Chrysocoma ciliata-Aristida congesta Sub-community
3.2.2 Eriocephalus ericoides-Acacia torti/is Sub-communltv
3.2.3 Schmidtia pappophoroides-Dimorphotheca zeyheri Sub-community
3.2.4 Acacia tortttis-ëreprostis obtusa Community
4 Rhigozum trichotomum-Acacia karroo Major Community
4.1 Enneapogon scaber-Rhigozum trichotomum Community
4.2 Sarcostemma viminale-Rhigozum trichotomum Community
4.3 Hertia pallens-Rhigozum tricnotomum Community
4.4 Euryops multifidus-Rhigozum trichotomum Community
DESCRIPTION OF THE COMMUNITIES
1 Tarchonanthus camphoratus-Acacia mellifera Major community
This major community is to be found on the rocky areas in the south western
parts of the study area. These sites are usually situated on shallow soil on the
(
130
slopes of hills, but are also associated with the dry plateau edges.
Geologically, the area is underlain by the Tierberg Formation of the Ecca
Group. Outcrops of Karoo dolerite mainly occur in the region of the
Vanderkloof Dam. According to Werger (1973), the southern Kalahari
represents a marginal savanna area on deep sandy soils. Acacia mellifera is
especially abundant in the Vryburg area (Werger 1973).
Species group J of the phytosociological table (Table 5.1) differentiate this
vegetation unit with Acacia mellifera (species group J), the shrub
Tarchonanthus camphoratus and the thorny shrub Protasparagus suaveolens
(species group P) the differentiating species. The constant occurrences of the
grass, Heteropogon contortus (species group AB), further differentiate this
plant community (Table 5.1).
Six distinct vegetation units further differentiate this major community
(Table 5.1).
1.1 Acacia mellifera-Schmidtia pappophoroides Community
This vegetation unit is found on the plateaux of low dolerite hills. Big dolerite
boulders (> 1 metre in diameter) are visible on the soil surface. The
vegetation is partly overgrazed and veld fires occurred regularly. According to
McCabe (1987), grazing is not the only method of defoliation in the Karoo. He
suggests that fire is an "aid" to veld management and not a solution to
problems and that the use of fire must .alwavs be linked to the management
process occurring before and after the burn takes place.
This plant community lacks diagnostic species, but is rather characterized
by the dominance of Acacia mellifera (species group J, Table 5.1). According
to Carr (1976), A. mellifera is extremely drought resistant and has a
preference for deep, sandy or gravelly soils. This was not the case here, as
dolerite hills are mainly rocky with shallow soils. The Acacia mellifera-
Schmidtia pappophoroides Community has a low species diversity with the
shrub Tarchonanthus camphoratus (species group P) the only other
noteworthy woody species present. Schmidtia pappophoroides (species group
131
S), Heteropogon contortus, Enneapogon scoparius and Aristida diffusa
(species group AB) are the only noteworthy grasses found.
1.2 Acacia mellifera-Hermannia comosa Community
This plant community is found on the south-facing midslopes of dolerite hills.
Large boulders are absent, but more than 50% of the soil surface is covered
with rocks « 1 m in diameter) and stones.
Hermannia comosa (species group A) is the only differentiating species.
This species often grows in extremely rocky habitat and is absent from the
Acacia mellifera-Schmidtia pappophoroides Community (Table 5.1). Woody
species are scarce and only the thorn tree, Acacia mellifera (species group J),
and the shrub, Tarchonanthus camphoratus (species group T), are present.
The latter can reach heights of up to 6 metres, but seldom exceeds 2 metres
in height here. Other woody species include Acacia karroo (species group
AA). Protasparagus suaveolens (species group P) is the only noteworthy
shrub (Table· 5.1). The grasses Heteropogon contortus and especially
Themeda triandra (species group AB) occasionally have high constancies
(Table 5.1).
1.3 Rhus burchellii-Lantana rugosa Community
The Rhus burchellii-Lantana rugosa Community is encountered on relatively
dry to dry north-facing slopes and on flat plateaux of low hills. The soils are
generally shallow « 100 mm deep) with a high percentage (often higher
than 70%) of surface rock.
The diagnostic species of this vegetation unit are the shrub, Rhus
burchellii, and the forb, Lantana rugosa (species group B). R.· burchellii
commonly occurs in rocky ravines and ridge veld (Venter & Joubert 1985).
The grass, Heteropogon contortos (species group AB), is the only grass
species occurring throughout the entire plant community (Table 5.1).
132
1.4 Barleria rigida-Fingerhuthia africana Community
This community frequently occurs on the relatively dry to dry and often
disturbed/degraded footslopes of rocky ridges. The soil is of a calcareous
nature and the surface is often covered with wind-blown sand.
There are no diagnostic species for this vegetation unit, but species of
species groups C, 0, F, J and P constantly occur. Barleria rigida (species
group C), Justicia cuneata (species group D), Fingerhuthia africana (species
group F), Acacia mellifera (species group J) and Tarchonanthus camphoratus
(species group P) are the most abundant species differentiating this
vegetation unit. Tree and shrub species are scarce and only Acacia mellifera
(species group J) and Tarchonanthus camphoratus (species group P) are
conspicuous.
Two distinct sub-communities further differentiate this plant community
(Table 5.1).
1.4.1 Justicia cuneata-Barleria rigida Sub-community
This sub-community frequently occurs in bottomland situations with
moderately to poorly drained calcareous soil. Fine gravel covers 60-70% of
the soil surface.
This vegetation unit mainly differs from the Justicia cuneata-Acacia
mellifera Sub-community by a lower cover-abundance of Acacia mellifera
(species group· J), but higher cover-abundances of Barleria rigida (species
group C), Justicea cuneata (species group D) and Tarchonanthus
camphoratus (species group Pl. Lycium cinereum, Polygala uncinata and
Abutilon pycnodon (species group D) are exclusive to this vegetation unit
(Table 5.1).
133
1.4.2 Justicia cuneata-Acacia mellifera Sub-community
This plant community is restricted to the well-drained, sandy soils which
generally have a layer of clayey soil underneath (duplex soils). Exposed rocks
cover 20-30% of the soil surface.
This plant community does not contain exclusive diagnostic species, but is
rather differentiated by the high cover-abundance of particularly Justicia
cuneata (species group E). Other species also regularly occurring, include the
grasses, Sporobolus fimbriatus (species group G), Fingerhuthia africana
(species group I) and Enneapogon scoparius (species group AE). Tree species
are scarce and only Acacia me/lifera (species group N), of which the average
height do not exceed 1 m, is worth mentioning (Table 5.1).
1.5 Melhania rehmannii-Justicia protracta Community
This plant community is encountered on the footslopes of north- and west-
facing hills where the vegetation was found to be disturbed throughout.
Pieces of fine gravel from upslope virtually cover all of the exposed soil
surface.
Melhania rehmannii and Justicia protracta (species group E) are exclusive
to this vegetation unit. The thorn tree Acacia me/lifera (species group J),
generally not higher than 2 metres, is often extremely dominant and occurs
throughout the community (Table 5.1).
Two distinct sub-communities further differentiate this vegetation unit
(Table 5.1).
1.5.1 Melhania rehmannii-Justicia cuneata Sub-community
This sub-community is found on the footslopes of north-facing hills' where
soils of a calcareous nature are prominent. The well-drained sandy soils are
often trampled. Pieces of fine gravel cover the soil surface.
134
This vegetation unit lacks diagnostic species (Table 5.1). The restricted
dominance of Justicia cuneata (species group Dl, are differentiating with
Acacia mellifera (species group Jl, the only conspicuous tree present. Like the
woody species, grasses are also limited with only Fingerhuthia africana
(species group F), Themeda triandra, Heteropogon contortus and Enneapogon
scoparius (species group AB) having patchy occurrences. The forb,
Corbichonia decumbens (species group F), is quite abundant, especially in
crevices between rocks.
1.5.2 Melhania rehmannii-Acacia mellifera Sub-community
This sub-community is encountered on the footslopes of west-facing hills.
Like in the Melhania rehmannii-Justicia cuneata Sub-community, this
vegetation unit is overgrazed and disturbed. Fine gravel, covering the soil
surface, and dolerite rock sheets are prominent. This vegetation unit does not
contain diagnostic species which are restricted to this specific plant
community (Table 5.1).
Acacia mellifera is the only conspicuous tree species and has, with the
exception of one relevé (relevé 78), a high cover-abundance. This is a limited
plant community with Acacia mellifera (species group J) more abundant than
in the Melhania rehmannii-Justicia cuneata Sub-community (Table 5.1 l. Only
a few other species occur of which the shrub Ehretia rigida (species group
AB) are among the subordinate shrubs with a low cover-abundance. The
grass Enneapogon scoparius (species group AB) are locally dominant (Table
5.1 ).
1.6 Cenchrus ciliaris-Hermannia vestita Community
This extensive community occupies a relatively wetter habitat than the
Melhania rehmannii-Justicia protracta Community. It is restricted to the
dolerite hills near the Vanderkloof Dam in the southern part of the study area.
135
Big dolerite boulders are a common sight and the soil of the often steep
slopes (> 60°) is rocky.
This community is differentiated by Acacia mel/ifera (species group J) and
Cenchrus ciliaris (species group I). Acacia tortiiis (species group V) also
frequently occurs (Table 5.1). Heteropogan contortus (species group AB) is
the only frequently occurring grass species (Table 5.1).
2 Grewia flava-Cenchrus ellieris Major Community
This vegetation unit is restricted to rocky habitat at the footslopes of hills and
ridges. Gravel due to continuous erosion of the upper layers cover the soil
surface. Trampling effect of livestock is obvious.
The shrub, Grewia flava (species group Hl, and the grass, Cenchrus ellieris
(species group I), are the differentiating species present (Table 5.1). Other
abundant woody species include the thorn trees, Acacia mel/ifera (species
group J) and A. tortiiis (species group V) and to a lesser extent, the shrub,
Ehretia rigida (species group AB, Table 5.1).
2.1 Grewia flava-Fingerhuthia africana Community
The Grewia flava-Fingerhuthia africana Community was found to be scarce,
being mostly associated with rocky soil, covered by a thin layer of wind-
blown sand. Calcareous stones are present and nearly covered by fine sand.
This vegetation unit lacks any diagnostic species (Table 5.1) and is
differentiated by the constant occurrence of Grewia flava (species group H),
as well as the restricted dominance of Cenchrus citieris (species group I) and
Acacia mel/ifera (species group J). The thorn tree, Acacia tortiIis (species
group Y), also occurs, but seldom exceeds two metres in height.
136
2.2 Cenchrus ciliaris-He/ichrysum /ineare Community
This community is generally found on rocky soil among big boulders. The
habitat is better protected by these big boulders than in the Grewia flava-
Fingerhuthia africana Community. The habitat is lower-lying and the soil is of
a clayey nature. Surface rocks are present and are more conspicuous than in
the Grewia flava-Fingerhuthia africana Community.
Species of species groups G and H differentiate this vegetation unit - all of
which have a low cover-abundance (Table 5.1). Noteworthy is the dominance
of Cenchrus ciliaris (species group I) and the absence of Fingerhuthia africana
(species group F, Table 5.1). Also conspicuous are the presence of species of
species group K, which are absent in the Grewia flava-Fingerhuthia africana
Community. Conspicuous woody species include Grewia flava (species group
H), with a restricted dominance, Acacia mellifera (species group J) and A.
torti/is (species group V).
3 Acacia tortilis-Heteropogon contortus Major Community
The Acacia tortilis-Heteropogon contortus Major Community is found in the
north-western corner of the study area in the Jacobsdal District. This
vegetation unit is mainly associated with the bottomlands at the footslopes of
low hills and on the adjacent plains. These soils generally have a high base
status (Land Type Survey Staff, in press). Two areas are distinguishable
namely one to the north and one to the south of Jacobsdal. The soils of the
southern part (Ae land type) are generally deeper (> 300 mm deep) (Land
Type Survey Staff, in press). The soils of the Ag land type in the northern
part are shallow « 300 mm deep) and are often very rocky (Land Type
Survey Staff, in press).
The Tierberg Formation of the Ecca group is the main geological formation.
As in the Acacia mellifera-Heteropogon contortus Major Community, dolerite
dykes occur, but to a much lesser extent and these are virtually restricted to
the higher-lying areas.
137
The presence of the species of species group V in the phytosociological
table (Table 5.1) together with the absence of Acacia mellifera (species group
J, Table 5.1) differentiate this vegetation unit. Acacia torti/is is the only
dominant tree species present. According to Venter & Joubert (1985) this
species is common to dominant in the western thornveld of the Free State.
According to Carr (1976), A. torti/is is more common in bushveld and lowveld
but extends also to the highveld areas of South Africa.
Six distinct communities further divide this vegetation unit (Table 5.1).
3. 1 Chei/anthes ecktoniene- Tarchonanthus camphoratus Community
This community is mainly associated with the foot- and midslopes of low hills
in the undulating landscape and adjacent plains. The soils of these situations
are generally deeper than 300 mm at the feet of the hills, but are markedly
shallower on the rocky slopes. The soil type is mostly of the Mispah form
with a shallow orthic A-horizon (Land Type Survey Staff, in press).
The vegetation is differentiated by the species .Iisted in species group N
(Table 5.1) which randomly occur in the relatively dry rocky areas of the
western Free State. Although not exclusive to this vegetation unit,
Tarchonanthus camphoratus (species group Nl and Acacia torti/is (species
group V) are the two dominant tree species present. The grass species,
Heteropogon contortus (species' group AB), is. often very abundant in
extremely rocky localities, but is less common in the low-lying areas.
Two distinct sub-communities are distinguishable in this vegetation unit
(Table 5.1).
3.1.1 Protasparagus mucronatus-Rhus ciliata Sub-community
This sub-community is associated with the footslopes of rocky hills with
rocks covering 80-90% of the soil surface.
138
This sub-community is dominated by Protasparagus mucronatus and Rhus
ciliata (species group L, Table 5.1). Other species also differentiating this
vegetation unit include Chenopodium album (species group K), Hermannia
vestita (species group L) and the fern, Chei/anthes eckloniana (species group
N). Noteworthy is the high constancy of Tarchonanthus camphoratus (species
group P). In contrast, Acacia torti/is (species group V),. has a patchy
occurrence. The herbaceous layer is well developed and prominent grasses
are Digitaria eriantha (species group N), Themeda triandra and Heteropogon
contortus (species group AB).
3.1.2 Chei/anthes eckloniana-Eragrostis echinochloidea Sub-community
This sub-community occurs on the low-lying plains at the footslopes of hills
along drainage lines. The soil is calcareous and covered by a thin layer of
sand. Overgrazing and trampling of the soil surface is a common
phenomenon.
The small grass, Eragrostis echinochloidea (species group M), is the only
diagnostic species present (Table 5.1). According to Van Oudtshoorn (1991),
this species grows well in disturbed habitat and IS indicative of habitat
disturbance and overgrazed pasture. Other grasses are limited, probably due
to habitat disturbance and are restricted to Digitaria eriantha (species group
N) and Heteropogon contortus (species group AB). Acacia torti/is (species
group V) is the only abundant tree and Tarchonanthus camphoratus (species
group P) the only prominent shrub present (Table 5.1).
3.2 Acacia tortilis-Maytenus polyacantha Community
This community is associated with drainage channels on the low-lying
footslopes of dolerite hills. The soil is clayey with fine gravel and pieces of
eroded rock, eroded from upslope, covering the soil surface.
This vegetation unit is differentiated by the presence of the species listed
in species group U (Table 5.1). Although not abundant, Mayten us
139
polyacantha, the thorny karroid dwarf shrub, Eriocephalus spineseens and the
grass, Aristida congesta, are the most important species. The presence of
Chrysocoma ei/iata is indicative of Karoo invasion (Anonymous 1968).
3.2.1 Chrysocoma ciliata-Ar/stida congesta Sub-community
This vegetation unit is situated on the low-lying sandy areas of dolerite hills.
The soil is deep (> 400 mm deep) and virtually no rocks or stones occur on
the soil surface. Habitat disturbance, due to overgrazing and trampling by
livestock, is evident. These areas are particularly vulnerable to soil erosion.
Elephantorrhiza elephantina (species group 0, Table 5.1) randomly grows
in deep sandy soil and is the only diagnostic species. Rhus ciliata (species
group L), Tarchonanthus camphoratus (species group P)" and May tenus
potvecenthe (species group U) and Acacia tortilis (species group V) are the
most important representatives of the woody component. Conspicuous
grasses are absent and only Aristida congesta (species group U) and
Heteropogon contortus (species group AB) have a restricted distribution
(Table 5.1).
3.2.2 Er/ocephalus ericoides-Acacia tortilis Sub-community
This community is found on dry low-lying plains with calcareous soils.
Calcareous - and dolerite stones cover the soil surface. The soil is poorly
drained and patches of overgrazing are a common phenomenon.
The Acacia tortilis-Eriocephalus ertcoldes Community is differentiated by
the presence of the species of species group Q with the karraid shrublet,
Er/ocephalus ericoides the most abundant, and which together with
Chrysocoma ciliata, give this sub-community a karroid appearance.
The shrub, Tarchonanthus camphoratus (species group P), is absent from
this vegetation unit. Acacia torti/is is the only dominant woody species
140
present (Table 5.1). Grasses are scarce and only Eragrostis curvu/a (species
group N) is worth mentioning (Table 5.1).
3.2.3 Schmidtia pappophoroides-Dimorphotheca zeyheri Sub-community
The Schmidtia pappophoroides-Dimorphotheca zeyheri Sub-community is to
be found in the extreme northern parts of the study area where soil is
generally deep (> 300 mm deep) and sandy. Limestone reefs occur in areas
where habitat disturbance is common.
Schmidtia pappophoroides (species group R) is the only abundant
diagnostic species. Dimorphotheca zeyheri, Hermannia modesta and the
small grass Ch/oris virgata are also diagnostic of this sub-community, but are
inconspicuous. Acacia tortilis (species group V) dominates this thornveld and
is the only conspicuous tree species present (Table 5.1).
3.2.4 Acacia torti/is-Eragrostis obtusa Sub-community
Like the Schmidtia pappophoroides-Dimorphotheca zeyheri Sub-community,
this vegetation unit is also very limited in area and generally has a low
species diversity (Table 5.1). The Acacia torti/is-Eragrostis obtusa Sub-
community also occurs on deep sandy soils of bottomland situations, but the
habitat is marginally wetter than that of the Schmidtia pappophoroides-
Dimorphotheca zeyheri Sub-community, indicating somewhat better habitat
conditions.
B/epharis diversispina (species group T) differentiates this sub-community,
but the presence of the grass Eragrostis obtusa (species group S) is more
evident. The absence of species of species group R combined with the
presence of B/epharis diversispina (species group T) also differentiate this
vegetation unit from the Schmidtia pappophoroides-Dimorphotheca zeyheri
Sub-community. Acacia torti/is (species group V) is the onlv conspicuous
woody species present (Table 5.1).
141
4 Rhigozum trichotomum-Acacia karroo Major Community
This major community comprises overgrazed and trampled veld and is found
on shallow, rocky lithosols of loamy sand on the plateaux and gentle slopes,
rarely sloping more than 50. It also occurs on sites where the calcrete
plateaux are overlain by a thin layer of Kalahari sand. The latter is mainly
situated in the region of Petrusville in the south-western parts of the study
area. This woodland also occurs on the banks of some dry rivulets, especially
in upland situations. According to Bezuidenhout (1993) areas occupied by
Acacia karroo Woodland are often overgrazed and the advanced stage of
degradation is indicated by large areas of bare, compacted soil. This major
community is not to be confused with the Acacia karroo-Protasparagus
laricinus Major Community mentioned in Chapter 6 which is associated with
low-lying areas along public roads.
This vegetation unit is differentiated by the presence of only two species,
namely Rhigozum trichotomum and Acacia karroo (species group AA, Table
5.1). According to Carr (1976), Acacia karroo is more widely distributed than
any of our other acacias and occurs in varying climatic conditions in all
provinces of South Africa,' eastern Botswana, Swaziland and Lesotho.
The Rhigozum trichotomum-Acacia karroo Major Community subdivides
into four distinct communities (Table 5.1).
4.1 Enneapogon scaber-Rhigozum trichotomum Community
An infrequent community which occurs only on the rocky outcrops of dolerite
on the plateaux along the Orange River in the region of the Gariep Dam. The
soil is covered with large rock slabs.
Enneapogon scaber (species group W) differentiates this community and
grows extremely well between the rock slabs. Acacia karroo is infrequent and
is generally not higher than 1 metre, probably due to the shallow and rocky
soil. Sporobolus fimbriatus (species group DL Fingerhuthia africana (species
group F) and Cenchrus enteris (species group I) especially, further
142
differentiates this vegetation unit (Table 5.1). Also present, but less frequent,
.are Heteropogon contortus and Enneapogon scoparius (species group AB,
Table 5.1).
4.2 Sarcostemma viminale-Rhigozum trichotomum Community
Downstream from Orania, (just outside the study area in the Northern Cape),
the Ecca sandstones are frequently covered by sand which contains a fair
amount of gravel. Calcareous concretions constitute an important component
of these soils, and often the sand and gravel are completely cemented into
thick calcrete strata. The vegetation is disturbed and the soil trampled.
Sarcostemma viminale (species group X) is the differentiating species.
Only a few other species occur, of which Rhigozum trichotomum and Acacia
karroo are occasionally abundant (species group AA, Table 5.1 I. Graminoids
are conspicuously absent, probably due to the trampled condition of the
habitat.
4.3 Hertia pal/ens-Rhigozum trichotomum Community
This vegetation unit occurs on the calcareous-rich soils of the flat pediplains
of the south-western Free State. Dolerite and Ecca sandstone are overlain by
a layer of loamy Kalahari sand, possibly somewhat mixed with wind-blown
alluvial sand. It usually contains a small fraction of fine gravel. This soil is
relatively compacted, compared to the majority of the Kalahari sands.
Hertia pal/ens (species group .Y, Table 5.1 I is the only species
differentiating this plant community. This kartold species usually occurs under
extremely dry conditions where the pasture is overgrazed and the soil
trampled. Besides H. pal/ens, Rhigozum trichotomum and Acacia karroo are
the only abundant species present.
~-----------------------------------------------
143
4.4 Euryops multifidus-Rhigozum trichotomum Community
The Euryops multifidus-Rhigozum trichotomum Community is also associated
with calcareous-rich soils of the low-lying areas. Surrounding dolerite boulders
create a cooler and moister habitat than that of the Hertia pallens-Rhigozum
trichotomum Community. No gravel is visible on the soil surface.
Rhigozum trichotomum (species group AA), conspicuously dominant in this
vegetation unit, often forms very dense stands together with Acacia karroo
over large areas of trampled veld. Euryops multifidus (species group Z) grows
well in the low-lying areas, especially in areas where stagnant water occurs
for long periods of time.
ORDINATION
The distribution of the syntaxa along the first and second axes of the
DECORANA ordination (Hill 1979 b) is given in Figure 5.2. The first axis
illustrates a gradient of habitat disturbance (Figure 5.2). Also illustrated along
axis 1, is the distribution of plant communities associated with rocky and
sandy soils. Along the second axis, plant communities of bottomlands and the
footslopes of hills range at the top of the diagram, while communities
restricted to the hills and ridges as well as the plateaux are to the bottom.
The Grewia flava-Cenchrus ellieris Major Community is clearly a transition
between the Tarchonanthus camphoratus-Acacia mellifera Major Community
and the Acacia tortilis-Heteropogon contortus Major Community. The
DECORANA ordination (Figure 5.2) supports the Braun-Blanquet classification
(Table 5.1).
DISCUSSION
This is the first comprehensive ecological account of the Acacia communities
in the dry south-western Free State. All the major vegetation types and
associated plant communities could be related to specific environmental . I
~-----------------------------------------------------------
144
attributes. These communities all differ from one another, but certain
similarities are also noticeable. The woodland vegetation of the Acacia
communities are easily distinguishable and interpretable in the veld. The
grassland is being overgrazed and burnt. Field fires occur regularly and play
an important role in veld management. In this way the unpalatable grass
component is destroyed and new pioneer grasses have the chance to
establish.
The low species diversity and low successional status of the species are
ascribed to the degradation of the grassland and to bush encroachment. In
areas where thorn-bush encroachment is a problem, a cheap and effective
method of assisting the recovery of bare areas is to cover such areas with
brush which is cleared from the area before seeding. Normally such brush
decomposes after a few seasons and the little patches thus protected then
become available for grazing. However, in all cases of veld reclamation,
whether by natural or chemical means, sufficient recuperative rest during the
growing season in the ensuing years is essential if the reclaimed veld is to
maintain itself (Tainton 1984).
Acacia mel/ifera, A. torti/is, A. karroo and Rhigozum obovatum are the
most important differentiating species in the thornveld of the southern Free
State. Acacia mel/ifera is common in the south-western thornveld, while
Acacia tortilis is common to abundant in the western parts on calcareous
habitat of the south-western Free State. Acacia karroo is widely distributed
through the Free State and occurs especially along water courses and
drainage channels (See Chapter 6). In exceptional cases, Acacia karroo
encroachment may occur on overgrazed grassland vegetation. Rhigozum
obovatum is a widely distributed karroid species and is common to abundant
in stony veld and on hills. The most important grasses encountered in the
thornveld include Ar/stida congesta, A. diffusa, Enneapogon scoparius,
Eragrostis lehmanniana, Fingerhuthia africana, Heteropogon contortus and
Themeda triandra. Blephar/s diversispina, Chrysocoma ciliata, Hertie pal/ens,
Er/ocephalus ericaides, E. spinescens, Lveiurn cinereum, Pentzia globosa and
Salsola glabrescens are all elements from the Karoo vegetation, indicating the
strong relationship between these Acacia grassland communities and the
encroaching Karoo.
145
Conservation of these areas should receive high priority and these present
studies could be used as basis in doing so. The need to get a better
understanding of the thornveld vegetation in order to apply constructive
conservation techniques and in order to manage the resources in a better way
is necessary and should be high on the list of priorities.
. I
146
5.5 REFERENCES
ACOCKS, J.P.H. 1988. Veld types of South Africa, 3rd edn. Mem. bot. Surv.
S. A fr. 57: 1-146.
ANONYMOUS, 1968. Ken die Karoobossie. Landbouweekblad. National Media
Ltd., Cape Town.
ARNOLD, T.H. & DE WET, B.C. 1993. Plants of southern Africa: names and
distribution. Mem. bot. Surv. S. Afr. 62: 1-825.
BEZUIDENHOUT, H. 1993. Syntaxonomy and synecology of the western
Transvaal grasslands. Unpublished Ph.D. dissertation. University of
Pretoria, Pretoria.
BEZUIDENHOUT, H. & BREDENKAMP, G.J. 1990. A reconnaissance survey
of the vegetation of the dolomitic region in the Potchefstroom -
Ventersdorp - Randfontein area, South Africa. Phytocoenologia 18: 387-
403.
BREDENKAMP, G.J., JOUBERT, A.F. & BEZUIDENHOUT, H. 1989. A
reconnaissance survey of the vegetation of the plains in the
Potchefstroom-Fochville-Parys area. S. Afr. J. Bot. 55: 199-206.
BREDENKAMP, G.J. & THERON, G.K. 1978. A synecological account of the
Suikerbosrand Nature Reserve. 1. The phytosociology of the
Witwatersrand geological system. Bothalia 12: 513-529.
CARR, J.D. 1976. The South African Acacias. Conservation press (PTV.)
LTD. Johannesburg.
DU PREEZ, P.J. 1991. A syntaxonomical and synecological study of the
south-eastern Orange Free State and related areas with special reference
147
to Korannaberg. Unpublished Ph.D. dissertation. University of the Orange
Free State, Bloemfontein.
DU TOIT, A.L. 1954. The geology of South Africa. Oliver & Boyd, Edinburgh.
FULS, E.R. 1993. Vegetation ecology of the northern Orange Free State.
Unpublished Ph.D. dissertation. University of Pretoria, Pretoria.
HILL, M.O. 1979 a. TWINSPAN-A Fortran program for arranging multivariate
data in an ordered two-way table by classification of the individuals and
attributes. Department of Ecology and Systematics, Cornell University,
Ithaca, New York.
HILL, M.O. 1979 b. DECORANA-A Fortran program for detrended
correspondence analysis and reciprocal averaging. Department of Ecology
and Svstematics. Cornell University, Ithaca, New York.
HOFFMAN, M.T. 1996. Orange River Nama Karoo. In: Low, A.B. & Rebelo,
A.G. (eds). Vegetation of South Africa, Lesotho and Swaziland. Dept.
Environmental Affairs & Tourism, Pretoria.
KOOIJ, M.S., BREDENKAMP, G.J. & THERON, G.K. 1990. Classification of
the vegetation of the B land type in the north-western Orange Free State.
S. Atr. J. Bot. 56: 309-318.
LAND TYPE SURVEY STAFF (IN PRESS). Land Types of the maps 2924 -
Koffiefontein and 3024 - Colesberg. Mem. agric. nat. Resources. S. Atr.
No 14.
MALAN, P.W., VENTER, H.J.T. & DU PREEZ,P.J. 1996. Vegetation ecology
of the southern Free State: Plant communities of the Zastron area. S. Atr.
J. Bot. (Submitted).
McCABE, K. 1987. Veld management in the Karoo. The Naturalist 31 (1): 8-
15.
148
MENTIS, M.T. & HUNTLEY, B.T. 1982. A description of the Grassland Biome
Project. S. Afr. Nat. Sci. Prog. Rep. 62: 1-29.
MUELLER-DOMBOIS, D. & ELLENBERG, H. 1974. Aims and methods of
vegetation ecology. Wiley, New York.
MULLER, O.B. 1986. Plantekologie van die Willem Pretorius Wildtuin. Ph. D.
dissertation, University of the Orange Free State, Bloemfontein.
ROSSOUW, L.F. 1983. 'n Ekologiese studie van die boomgemeenskappe van
die Bloemfontein-omgewing, Oranje-Vrystaat. M.Sc. thesis, University of
the Orange Free State, Bloemfontein.
RUTHERFORD, M.C. & WESTFALL, R.H. 1994. Biomes of southern Africa-
an objective calegorization. Mem. bot. Surv. S. Afr. 63: 1-94.
SACS. 1980. Stratigraphy of South Africa. Part 1 (comp. L.E.Kent).
Lithostratigraphy of the Republic of South Africa, South West
Africa/Namibia, and the Republics of Botswana, Transkei and Venda. Dept ..
Mineral and Energy Affairs, Pretoria.
SCHEEPERS,J.C. 1975. The plant ecology of the Kroonstad and Bethlehem
areas of the Highveld Agricultural Region.D.Sc. thesis, University of
Pretoria, Pretoria.
SCHEEPERS, J.C. 1986. Grassland Biome Project: Proceedings of the
workshop on the classification and mapping. Ecosyst. Prog. Rep. 16: 1-
31.
SOIL CLASSIFICATION WORKING GROUP 1991. Soil classification.
A taxonomic system for South Africa. Memoirs on the Agricultural Natural
Recources of South Africa No 15. Department of Agricultural
Development, Pretoria.
149
TAINTON, N.M. 1984. Veld and pasture management in South Africa. Shuter
& Shooter, Pietermaritzburg.
VAN OUDTSHOORN, F.P. 1991. Gids tot grasse van Suid-Afrika. Briza
Publications, Arcadia, Pretoria.
VAN WYK, S. 1983. 'n Plantekologiese studie van die Abe Bailey-
natuurreservaat. M.Sc. thesis, Potchefstroom University for Christian
Higher Education, Potchefstroom.
VENTER, H.J.T. & JOUBERT, A.M. 1985. Klimplante, bome en struike van
die Oranje-Vrystaat. P.J. de Villiers, Bloemfontein.
WEATHER BUREAU, 1965. Climate of South Africa. General survey. Part.
8. WB 28. pp.330. Government printer, Pretoria.
WERGER, M.J.A. 1973. Vegetation geographical patterns as a key to the
past, with emphasis on the dry vegetation types of South Africa. Bothalia
14 (3 & 4): 405-410.
WESTHOFF, V. 1971. The dynamic structure of plant communities in relation
to the objectives of conservation. In: Duffey, E. & Watt, A.S. 1971. The
scientific management of animal and plant communities for conservation.
BlackweIl, Oxford.
WHITTAKER, R.H. 1978. Classification of plant communities. W. Junk, The
Hague.
150
CHAPTER 6
Vegetation ecology of the southern Free State
Vegetation ecology of the southern Free State: Riparian shrub
communities
151
CHAPTER 6
VEGETATION ECOLOGY OF THE SOUTHERN FREE STATE: RIPARIAN
SHRUB COMMUNITIES
6.1 INTRODUCTION
The necessity of detailed plant ecological studies as a basis for sound land-
use planning, management and research is widely recognized (Pentz 1938;
Codd 1949; Bayer 1970; Foran et al. 1986; Bosch et al. 1987). One of the
major projects in this respect is the Grassland Biome Project. The Grassland
Biome of South Africa covers approximately 27% of the country (Rutherford
& Westfall 1994). As a result of intensive agricultural practices and
urbanization, together with industrialization, the deterioration of the
grassland led to concern amongst decision-makers, resulting in the launch of
the Grassland Biome Project (Mentis & Huntley 1982).
One of the first priorities of this Project, was to determine the location
and extent of the major vegetation types within the Biome (Mentis &
Huntley 1982). The aim of this study was therefore to classify and describe
the riparian shrub communities in the southern Free State. This study also
fits in with a comprehensive phytosociological programme under the
Grassland Biome Project (Mentis & Huntley 1982; Scheepers 1987).
The physical environment (Chapter 2), description of the plant
communities of the Zastron Area (Chapter 3), those associated with the
rocky outcrops of the dry south-western Free State (Chapter 4) and Acacia
communities (Chapter 5), are discussed elsewhere in this dissertation. This
report primarily deals with shrub communities associated with low-lying
drainage channels and other relevant bottomland moist habitats. In contrast
to the mountainous habitats the communities associated with the
bottomlands display a generally lower species diversity. The habitat is fairly
unstable, due to seasonal flooding and drying which, together with the
frequent overgrazing of the area, have caused an advanced state of
degradation of the vegetation. The soil is often severely eroded and the
vegetation obviously disturbed.
152
Ross (1948) stated that continuous degradation of natural pasture in
many parts of the world is visible. The Karoo and adjacent grasslands are
also in a degradation phase (Tidmarsh 1948; Bezuidenhout 1993). Topsoil
with low « 0,5% organic Carbon) organic material content covers nearly
60% of the country, while sandy soil « 10% clay) covers nearly 30% of
the area (Van Oudtshoorn 1991). These soils are particularly vulnerable to
wind and water erosion. A number of scientists previously refer to the
continuous degradation of vegetation due to continuous erosion in South
Africa (Robertson 1968).
According to Du Preez (1991) the Acacietea karroo in the southern and
eastern Free State represents the thickets usually situated on well-developed
levees along rivers, streams and drainage lines, and is also present on
clayey soils on the low level terraces and flood plains adjacent to the rivers.
Vegetation of this class may also be found on deep alluvial or colluvial soils
on gradual footslopes of hills and ridges, usually situated near drainage lines
and rivers (Bredenkamp et al. 1989; Bredenkamp & Bezuidenhout 1990).
The Acacia kerroo-Rbiqozum trichotomum Community associated with
higher-lying areas is discussed in Chapter 5 of this dissertation.
Rivers and flood plains in the interior of South Africa are periodically and
seasonally flooded. This phenomenon results in erosion of top soils or
deposition of sand, clay and silt on river banks and flood plains. In such
disturbed habitats only pioneers and species with wide ecological amplitudes
can survive (Du Preez 1991).
Fire as a controlling factor of Acacia karroo encroachment is not always
successful (Trollope .1974). Evidence from the more arid thornveld of the
Eastern Cape (Du Toit 1972) has shown conclusively that fire is not
effective in killing Acacia karroo. Trollope (1974) has shown that only a
small proportion (9.3%) of A. kerroo is in fact killed by fire. The herbaceous
layer of these riparian communities is usually without a dense grass cover.
Dense stands of fire resistant mature tree and shrub species suppress the
growth of grasses and fires thus looses its detrimental effect (Trollope
1974). Observations made in the eastern Cape show that Acacia kerroo
153
was able to survive eight years in succession by coppicing after each burn
(Trollope 1974).
The widespread ploughing of arable land concomitant with livestock
grazing pressure, further result in the destruction and degradation of large
tracks of pristine vegetation and also play an important role in the
continuous eroding of arable soil in the study area. The extent of vegetation
retrogression, as well as the total land-area in question, is difficult to assess
or to quantify. A more detailed identification, description and determination
of the localities of the riparian shrub communities are thus needed.
6.2 STUDY AREA
The present study includes the southern Free State and is situated to the
south of the 29° 00' S latitude and to the west of the 27° 00' E longitude,
encompassing approximately 27 000 km2.
Two biomes can be distinguished in the study area, namely the
Grassland and Nama-Karoo Biomes (Rutherford & Westfall 1994). According
to Acocks (1953, 1988) the vegetation of these biomes in the southern Free
State is divided into six different veld types. Towns situated in the study
area are (from north to south) Bloemfontein, Petrusburg, Fauresmith,
Wepener, Zastron and Bethulle (Chapter 2).
The rainfall is erratic, especially in the western part of the study area
from where it increases and increases in an easterly direction from a 300-
400 mm/annum rainfa!l interval to a 600-800 mm/annum rainfall interval.
Slow-draining streams are common owing to the flatness of the terrain.
A detailed description of the study area and environmental attributes is
given in Chapter 2 of this dissertation.
154
6.3 METHODS
Relevés were compiled in 31 stratified random sample plots. Care was
taken to avoid sampling of severely degraded vegetation and excessively
disturbed areas.
Plot size was fixed at 100m2 which is in accordance with the plot size
used by Scheepers (1975), Bredenkamp & Theron (1978), Rossouw (1983),
Van Wyk (1983), MOller (1986), Du Preez (1991), Bezuidenhout (1993) and
Fuls (1993). For every plant species present in the sample plot, a cover-
abundance value was estimated according to the Braun-Blanquet scale
(Mueller-Dombois & Ellenberg 1974).
Two-way indicator species analysis (TWINSPAN) (Hill 1979 b) was
applied to the floristic data set in order to derive a first approximation of the
plant communities of the area. In order to determine vegetation gradients
and the relationship with environmental variables, Detrended
Correspondence Analysis (DECORANA) (Hill 1979 a) was applied to the
floristic data set.
Taxon and author names comply with those of Arnold & De Wet (1993).
6.4 RESULTS AND DISCUSSION
In the analysis of the vegetation, nine distinct vegetation units were
identified. Two major communities, grouped into five distinct plant
communities, were identified which are dominated by Acacia karroo and
Rhus tencee respectively. The distribution pattern of the low thicket
vegetation apparently depends primarily on the variations in irradiation (Fuls
1993) and rockiness of the soil surface. The hierarchical classification of the
vegetation stresses the correlation between habitat and communities in the
study area, as well as the relationships between communities. The
communities are classified as follows:
155
1 Acacia karroo-Diospyros Iycioides Major Community
1.1 Acacia karroo-Salix babylonica Community
1.2 Ziziphus mucronata-Protasparagus laricinus Community
1.2.1 Rhus pyroides-Lycium hirsutum Sub-community
1.2.1.1 Setaria verticil/ata-Chenopodium album Variant
1.2.1.2 Crassula lanceolata-Acacia karroo Variant
1.2.1.3 Rhus pyroides-Protasparagus laricinus Variant
1.2.2 Heteromorpha trifoliata-Nidorella resedifolia Community
2 Rhus lancea-Rhus burchellii Major Community
2.1 Olea europaea-Rhus lancea Community
2.2 Rhus erose-Rbus lancea Community
2.2.1 Diospyros austro-africana-Rhus lancea Sub-community
2.2.2 Heteropogon contortus-Rbus lancea Sub-community
2.3 ,Euclea ertspe-Rbus lancea Community
DESCRIPTION OF THE COMMUNITIES
1Acacia karroo-Protasparagus laricinus Major Community
This widespread shrub community is mainly associated with the low-lying or
slightly undulating plains along public roads. According to Carr (1976),
Acacia karroo is more widely distributed than any other Acacia species and
occurs in varying climatic conditions in all provinces of the Republic of
South Africa, eastern Botswana, Swaziland and Lesotho. Although Acacia
karroo is adaptable to a wide variety of conditions and soil forms (Carr
1976), the location of this major-community is restricted to areas where
wind-blown sand and gravel eroding from higher-lying areas often cover the
soil surface.
The vegetation is characterized by Acacia karroo (species group G, Table
6.1). According to Carr (1976), A. karroo was probably the first of the
South African acacias to have drawn the attention of early botanists. Other
widely spread trees include Ziziphus mucronata (species group F), Olea
156
europees, Diospyros Iycioides (species group H) and Rhus lancea (species
group M). Protasparagus laricinus (species group F) is the only abundant
shrub (Table 6.1). The sedge Cyperus longus (species group F) is also
common. Graminoids are scarce and are restricted to patchy occurrences of
Setaria verticil/ata (species group B), Eragrostis obtusa (species group F),
Themeda triandra and Sporobolus fimbriatus (species group M).
An average of 13 species per relevé was recorded for this major
community.
Two distinct communities further characterize this major-community
(Table 6.1).
1.1 Acacia karroo-Salix babylonica Community
This community represents azonal wetland-like vegetation and is present in
depressions or other bottomland situations. These bottomland situations
generally have soils with a higher clay content than those of upland areas.
No rocks or large stones are visible on the soil surface. The soil is poorly
drained and low-lying areas are inundated for long periods after rains.
Species of species group A (Table 6.1) characterize this community. The
diagnostic woody species are the exotics Salix babyionica, Schinus molle
and Nicotiana glauca, the reed Phragmites australis, the grass Tetrachne
dregei, as well as the shrublets Asclepias fruticosa and Melilotus alba (Table
6.1). According to Stirton (1978), Nicotiana glauca is indigenous in north-
western and central Argentina, Paraguay and Bolivia and commonly occurs
along public roads in dongas and on river beds. The alkaloid present in N.
glauca, nicotine, mainly causes nervous symptoms such as twitching,
shaking and shivering. Abdominal pain and breathing difficulties and vision
disturbancees may also occur (Tampion 1982). Phragmites australis
sometimes is heavily grazed by livestock and generally does not exceed 1
metre in height. Acacia karroo (species group G) has an extremely high
cover-abundance and completely dominates the vegetation, with Diospyros
Iycioides (species group H) also generally encountered (Table 6.1).
157
An average of eight species per relevé was recorded for this community
1.2 Ziziphus mucronata-Protasparagus laricinus Community
This plant community can be found on the relatively well-drained, clayey
soils of riverbanks. The soil is drier than that of the Acacia karroo-Salix
babylonica Community. Habitat disturbance due to continuous overgrazing
and trampling of livestock and occasional flooding is reflected in the species
composition (Table 6.1).
Species listed in species group F, with Ziziphus mucronata and Celtis
africana the only exclusive diagnostic tree species, differentiate this
vegetation unit (Table 6.1)., Protasparagus laricinus, P. suaveolens and
Lycium cinereum (species group F) are the most abundant shrubs. The reed;
Cyperus longus, normally associated with wetlands (Eckhardt et al. 1993),
the forb, Tagetes minuta, and the climber, Clematis brachiata, are the only
other abundant and differentiating species (species group F, Table 6.1).
Other conspicuous species include the trees, Acacia karroo (species group
G), Olea europaea, Diospyros Iycioides (species group H) and Rhus lancea
(species group M). The height of these trees varies between 4-5 metres.
An average of 15 species per relevé was recorded.
This plant community is divided into two distinct sub-communities (Table
6.1) .
1.2.1 Rhus pyroides-Lycium hirsutum Sub-community
This bottomland vegetation occurs on seasonally wet, well-drained sandy
soils of riverbeds. The habitat is fairly unstable due to seasonal flooding and
drying. Overgrazing of pasture and trampling of livestock frequently occurs.
158
Species listed in species group D differentiate this sub- community.
Lycium hirsutum and Rhus pyroides (species group D) are the only abundant
and differentiating shrubs and Panicum maximum the only differentiating
grass (Table 6.1). Other conspicuous trees and shrubs include Ziziphus
mucronata (species group F), Acacia karroo (species group G), Diospyros
Iycioides (species group H) and Rhus lancea (species group M) with Celtis
africana (species group F) and Olea europaea (species group H) less
abundant (Table 6.1).
Three distinct variants further characterize this plant community (Table
6.1) .
1.2.1.1 Setaria verticil/ata-Chenopodium album Variant
The Setaria verticil/ata-Chenopodium album Variant occurs in full sun and is
restricted to the disturbed and overgrazed zones of dry riverbeds. Duplex
soils are prominent. Large trees are absent and the maximum height of tree
species does not exceed two metres.
The two diagnostic species are pioneers which colonize disturbed
habitats. They are the grass Setaria verticil/ata and the forb Chenopodium
album (species group B, Table 6.1). The absence of Olea europaea (species
group H) also characterizes this vegetation unit. Acacia karroo (species
group G) is inconspicuous and has an average height of only 0.3 metres.
Conspicuous species include the sedge, Cyperus longus (species group F),
with Rhus pyroides (species group D) and R. lancea (species group M) small,
but numerous. Forbs are inconspicuous and are restricted to Chenopodium
album (species group B), Tagetes minuta, Artemisia afra and Zinnia
peruviana (species group F), as well as the climber Clematis brachiata
(species group F)
An average of 18 species per relevé was recorded (Table 6.1).
159
1.2.1.2 Crassula lanceolata-Acacia karroo Variant
This entity is associated with wet riverbeds at the footslopes of dolerite
hills. The undergrowth of this vegetation unit occurs in the full shade of the
tree canopy. The soil is sandy with fine gravel from upslope (often 200 mm
deep) visible on the surface. This habitat is wetter than that of the Setaria
verticil/ata-Chenopodium album Variant.
This variant is not well developed. Crassula lanceolata and Pol/ichia
campestris (species group C) are the only differentiating species. Acacia
karroo (species group G), the most abundant tree species, generally exceeds
three metres in height. Rhus pyroides (species group D), Celtis africana,
Ziziphus mucronata (species group F) and Diospyros Iycioides (species group
H) are more abundant here than in the Setaria verticil/ata-Chenopodium
album Variant. The presence of Olea europaea (species group H) also
differentiates this variant from the Setaria verticittete-Cbenooodium album
Variant (Table 6.1). Olea europaea is shrub-like and generally does not
exceed two metres in height.
1.2.1.3 Rhus pyroides-Protasparagus laricinus Variant
This vegetation unit also occurs in dry riverbeds with a thick (50-100 mm)
layer of gravel, which gives it a rocky appearance, covering the soil surface.
The deeper soil layers are clayish, moist and deep « 100 mm deep). .
Diagnostic species are absent (Table 6.1). The most abundant shrubs are
Rhus pyroides (species group D) and Diospyros lycioides (species group H).
Acacia karroo (species group G) and Rhus lancea (species group M) are,
although inconspicuous, the most abundant trees. The sedge Cyperus
longus (species group F) often forms dense stands. Noteworthy is the
absence of Celtis africana (species group F) and the scanty occurrence of
Acacia karroo (species group G) and Olea europaea (species group H).
Graminoids are scarce and restricted to Panicum maximum (species group
D), Themeda triandra and Sporobolus fimbriatus (species group M).
160
An average of 15 species per relevé was recorded (Table 6.1).
1.2.2 Heteromorpha trifoliata-Nidorella resedifolia Sub-community
This community is restricted to moist bottomland situations where poorly
drained calcareous soils occur. The soil is calcareous-clayey and calcareous
stones are visible on its surface. The deeper soil layers associated with this
sub-community were found to be generally more clayey than those
associated with the Rhus pyroides-Lycium hirsutum Sub-community.
The vegetation is overgrazed and the shrub, Heteromorpha trifo/iata,
generally not higher than two metres, and the forb, Nidorella resedifo/ia
(species group I), are diagnostic (Table 6.1). Acacia karroo, generally not
exceeding two metres in height, and Ziziphus mucronata (2-4 metres)
(species group F) are the most abundant tree species. Other tree species
present, include Olea europaea (species group H) and Rhus /ancea (species
group M) with R. ciliata (species group Jl the only locally abundant shrub
(Table 6.1 I. The absence of Diospyros /ycioides (species group Hl, as well
as the absence of species from species groups A-D, I, K and L, also
differentiates this sub-community from the Rhus pyroides-Lycium hirsutum
Sub-community (Table 6.1).
2 Rhus /ancea-Rhus burchellii Major Community
The Rhus /ancea-Rhus burchellii Major Community is chiefly associated with
drainage channels at the footslopes of low hills. The habitat is more rocky
than that of the Acacia karroo-Diospyros /ycioides Major Community. Big
dolerite rocks from upslope often cover more than 50% of the soil surface.
The soil surface is often severely eroded and dongas are conspicuously
observable.
Rhus /ancea and R. burchellii (species group Ml are the only widely
dispersed woody species. Rhus erosa (species group K) and R. ciliata have a
more restricted distribution (Table 6.1). R. erosa, especially, is common to
161
dominant on more arid mountain slopes and hills (Venter & Joubert 1985).
Signs of overgrazing are obvious in some cases, with the pioneer species
Aristida diffusa prominently present (species group I, Table 6.1). Themeda
triandra and Sporobolus fimbriatus (species group M) are the only other
relatively common graminoids (Table 6.1).
An average of seven species per relevé was recorded (Table 6.1).
Three communities are distinguishable (Table 6.1).
2.1 Olea europaea-Rhus lancea Community
This vegetation unit is restricted to the footslopes of rocky hills. The slopes
,face mainly in a southerly direction, explaining the higher moisture
.conditions of the soil. Soils of the Mispah Form is typical of this habitat with
surface-rock percentages exceeding 20%. Big dolerite rocks are common,
covering 20-50% of the soil surface. The soil is shallow « 100 mm deep)
and rocky.
Diagnostic species are absent, but the vegetation is rather characterized
by the exceptional dominance of Rhus lancea (species group M, Table 6.1).
Olea europaea and Diospyros tvcioides (species group H) are the only other
conspicuous tree species present. Aristida diffusa (species group I) and
Rhus burchellii (species group M) are the only noteworthy grass and shrub
species respectively (Table 6.1).
An average of seven species per relevé was recorded (Table 6.1.).
2.2 Rhus erosa-Rhus lancea Community
The Rhus erosa-Rhus lancea Community is also found along the footslopes
of rocky hills. The aspects are south and south-west. The soil is well-drained
and sandy with exposed rocks covering less than 20% of the soil surface.
162
Fine gravel virtually cover the soil surface, especially in the lower-lying
areas.
Rhus erose (species group K) is very conspicuous and the only
differentiating species present (Table 6.1). Rhus lancea (species group M),
together with R. erosa (species group K) and R. burchellii (species group M)
often form dense stands, especially in the lower-lying areas (Table 6.1).
Two sub-communities further differentiate this plant community (Table
6.1 ).
2.2.1 Diospyros austro-africana-Rhus lancea Sub-community
This sub-community is encountered on well-drained sandy soils of south-
west facing slopes where deep dongas are a common phenomenon. Signs
of overgrazing are obvious. The different soil types to be found vary from
shallow « 100 mm) to deep (> 200 mm). The soil is less rocky than in the
Heteropogon contortus-Rhus lancea Sub-community.
This sub-community lacks exclusive diagnostic species (Table 6.1).
Diospyros Iycioides (species group H) and Rhus lancea (species group M)
are the most conspicuous tree species present. R. lancea, here less
prominent than in the Heteropogon contortus-Rhus lancea Sub-community,
generally does not exceed two metres in height. Rhus erosa (species group
K) and Diospyros austro-africana (species group K) are the most prominent
shrubs. The absence of Heteropogon contortus and Rhigozum obovatum
(species group J), as well as the presence of Diospyros Iycioides and D.
austro-africana further differentiate this sub-community from the
Heteropogon contortus-Rhus lancea Sub-community (Table 6.1).
2.2.2 Heteropogon contortus-Rhus lancea Sub-community
This sub-community is associated with well-drained sandy-rocky soils. The
aspect is south. Rock slabs cover 60% of the soil surface. Fine gravel and
163
dolerite stones are visible on the surface, leaving the rock slabs virtually
unexposed.
Heteropogon contortus (species group J), absent in the Diospyros austro-
africana-Iancea Sub-community, is the only diagnostic grass present with
the shrub, Rhigozum obovatum (species group J), the only diagnostic shrub
(Table 6.1). This sub-community lacks species from species group H, which
are evident in the Diospyros austro-africana-Rhus lancea Sub-community
(Table 6.1). A further characteristic of this vegetation unit is the partial
dominance of Rhus lancea and R. burchellii (species group M) respectively.
R. ciliata (species group J) is widespread and is the only other prominent
shrub. The grasses, Themeda triandra (species group M), and Aristida
diffusa (species group I) are the only noteworthy graminoids present (Table
6.1) .
2.3 Euclea crispa-Rhus lancea Community
The Euclea ertspe-Rbus lancea Community is restricted to the rocky low-
lying areas of the foot of dry north-facing hillslopes. Big dongas are common
with a thick layer of gravel (100-200 mm) covering the soil surface. The soil
is shallow « 100 mm), rocky (> 60 %) .and of the Mispah Form.
The shrub, Euclea crispa (species group L), differentiates this plant
community (Table 6.1). Rhus lancea (species group P) is totally dominant
and is the only conspicuous tree present (Table 6.1). Graminoids are poorly
represented and only Themeda triandra and Sporobolus fimbriatus (species
group Ml are worth mentioning (Table 6.1).
ORDINATION
In the scatter diagram the distribution of syntaxa along the first and second
axes of the DECORANA ordination is given (Figure 6.1). No clear
discontinuity exists between the different communities. It was thus decided
to restrict the ordination to the two major-communities. Clear discontinuity
164
can be observed and the major plant communities are restricted to specific
areas in the diagram. The first axis illustrates a gradient which may be
related to altitude and rockiness of the soil surface. Plant communities
associated with the rocky drainage channels and the footslopes of hills
(Rhus lancea-Rhus burchellii Major Community) are to the right of the
diagram while communities of the lowlands and undulating terrain with less
rocky soil (Acacia karroo-Diospyros Iycioides Major Community) are to the
left of the diagram. Along the second axis a moisture gradient exists. Plant
communities in wet areas are situated at the top. The moisture decreases
towards the bottom with the communities associated with dry habitat
situated at the bottom of the diagram (Figure 6.1).
DISCUSSION
The riparian shrub communities of the southern Free State is in a state of
degradation, because of a relatively low rainfall for the last number of years
and a continuous degradation of vegetation. Yet, all the plant communities
could be related to specific environmental conditions in the field. It is
important to note that, although some of these communities show strong
affinities with the vegetation associated with rocky outcrops in the study
area (Chapter 4), all these communities were encountered in bottomland
situations and drainage channels. The habitat is fairly unstable, due to
seasonal flooding and drying which, together with the frequent overgrazing
of the area play an important role in the degradation of the vegetation. The
strong presence of certain woody species within the drainage channels is
ascribed to the favorable moisture regimes in these areas. Habitat
disturbance (especially in areas along public roads) frequently occurs.
It is clear that plant communities are dynamic and may display changes
in species composition according to the habitat. According to Eckhardt
(1993) veld in a good condition is usually characterized by a high basal
cover of high ecological status species. The low cover of ecological
important grasses ·is further indicative of veld in a poor condition (Van
Oudtshoorn 1991). The riparian shrub vegetation can therefore be described
as veld in a poor condition. The most important woody species are Acacia
~--------------------------------------------------------------------------- -
165
karroo, Diospyros Iycioides, Protasparagus laricinus, Rhus burchellii, R.
ciliata, Rhus lancea and Ziziphus mucronata. Acacia karroo, Diospyros
Iycioides and Rhus lancea are the most important differentiating species.
Themeda triandra and Sporobolus fimbriatus are the most abundant grasses.
Signs of overgrazing are obvious in some cases with the pioneer species
Aristida diffusa prominently present. According to Van Oudtshoorn (1991),
A. diffusa is an unpalatable grass and can be seen as indicative of
overgrazed pasture.
Ecologically sound conservation management programs should take this
present delineation of the riparian shrub communities as the basis for future
management planning. The restricted distribution of these communities
emphasize the fact that these areas should be given higher conservation
priority.
166
6.5 REFERENCES
ACOCKS, J.P.H. 1953. Veld types of South Africa. Mem. bot. Surv. S. Afr.
28: 1-192.
ACOCKS, J.P.H. 1988. Veld types of South Africa. 3 rd edn. Mem. bot.
Surv. S. Afr. 57: 1-146.
ARNOLD, T.H. & DE WET, B.C. 1993. Plants of southern Africa: names
and distribution. Mem. bot. Surv. S. Afr. 62: 1-825.
BAVER, A.W. 1970. Plant ecology in the service of man in southern Africa.
S. Afr. J. Sci. 66: 71-77.
BEZUIDENHOUT, H. 1993. Syntaxonomy and synecology of the western
Transvaal grasslands. Unpublished Ph.D. dissertation. University of
Pretoria, Pretoria.
BOSCH, O.J.H., JANSE VAN RENSBURG,F.P. & TRUTER, S. DU T. 1987.
Identification and selection of benchmark sites on Litholic soils of the
western Grassland Biome of South Africa. J. GrassI. Soc. Sth. Afr. 4:
143-147.
BREDENKAMP,G.J. & BEZUIDENHOUT,H. 1990. The phytosociology of the
Faan Meintjes Nature Reserve in the western Transvaal grassland, South
Africa. S. Afr. J. Bot. 56: 54-64.
BREDENKAMP, G.J. JOUBERT, A.F. & BEZUIDENHOUT, H. 1989. A
reconnaissance survey of the vegetation of the plains in the
Potchefstroom-Fochville-Parys area.·S. Afr. J. Bot. 55: 199-206.
BREDENKAMP,G.J. & THERON, G.K. 1978. A synecological account of the
Suikerbosrand Nature Reserve. 1. The phytosociology of the
Witwatersrand geological system. Bothalia 12: 513-529.
167
CARA, J.D. 1976. The South African Acacias. Conservation press (PTY.)
LTD. Johannesburg.
CODD, L.E.W. 1949. The application of ecology to agricultural problems in
South Africa. In: Statement and communication of the African Regional
Scientific Conference, 17-28 Oct. Johannesburg, pp. 115-119.
DU PREEZ, P.J. 1991. A syntaxonomical and synecological study of the
vegetation of the south-eastern Orange Free State and related areas with
special reference to Korannaberg. Ph.D. dissertation. University of the
Orange Free State, Bloemfontein.
DU TOIT, P.F. 1972. The goat in a bush-grass community. Proc. Grassld.
Soc. Sth. Afr. 7: 44-50
ECKHARDT, H.C. 1993. A synecological study of the vegetation of the
north-eastern Orange Free State. Unpublished M.Sc. thesis. University of
Pretoria, Pretoria.
ECKHARDT, H.C., VAN ROOYEN, N. & BREDENKAMP, G.J. 1993. Wetland
plant communities of the Vrede-Memel-Warden area, north-eastern
Orange Free State. Navors. nes. Mus. Bloemfontein. 9(8): 246-262.
FORAN, B.D., BASTIN, G, & SHAW, K.A. 1986. Range assessment and
monitoring in arid lands: the use of classification and ordination in range
survey. J. envir. Mgmt. 22: 67-84.
FULS, E.R. 1993. Vegetation ecology of the northern Orange Free State.
Unpublished Ph.D. dissertation. University of Pretoria, Pretoria.
HILL, M.O. 1979 a. DECORANA - a FORTRAN program for detrended
correspondence analysis and reciprocal averaging. Department of
Ecology and Systematics, Cornel! University, lthaca, New York.
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HILL, M.O. 1979 b. TWINSPAN - a FORTRAN program arranging
multivariate data in an ordered two-way table by classification of
individuals and attributes. CornelI University, Ithaca, New York.
MENTIS, M.T. & HUNTLEY, B.J. 1982. A description of the Grassland
Biome Project. S. Atr. Nat. Sci. Prog. 62: 1-29.
MUELLER-DOMBOIS, D. & ELLENBERG, H. 1974. Aims and methods of
vegetation ecology. Wiley, New York.
MOLLER, D.B. 1986. Plantekologie van die Willem Pretorius Wildtuin. Ph.
D. dissertation, University of the Orange Free State, Bloemfontein.
PENTZ, J.A. 1938. The value of botanical survey and the mapping of
vegetation as applied to farming systems in South Africa. Mem. bot.
Surv. S. Atr. 19: 1-15.
ROBERTSON,T.C. 1968. Soil is life. Cape and Transvaal Printers, Kaapstad.
ROSS, J.C. 1948. Land utilization and soil conservation in the Union of
South Africa. Bulletin. Div. Soil Con. and Ext., Dept. of Agriculture,
Pretoria.
ROSSOUW, L.F. 1983. 'n Ekologiese studie van die boomgemeenskappe
van die Bloemfontein-omgewing, Oranje-Vrystaat. M.Sc. thesis,
University of the Orange Free State, Bloemfontein.
RUTHERFORD,M.C. & WESTFALL, R.H. 1994. Biomes of southern Africa -
an objective categorization. 2 nd edn. Mem. bot. Surv. S. Atr. 63: 1-
94.
SCHEEPERS,J.C. 1975. The plant ecology of the Kroonstad and Bethlehem
areas of the Highveld Agricultural Region. D.Sc. thesis, University of
Pretoria, Pretoria.
169
SCHEEPERS, J.C. 1987. Grassland Biome Project: Proceedings of the
workshop on the classification and mapping. S. Afr. Ecosys. Prog. Dcc.
Rep. Series 16: 1-31.
STIRTON, C.H. 1978. Indringerplante. Mooi, maar gevaarlik. Department of
Nature Conservation. Cape Provincial Administration. Cape Town.
TAMPION, J. 1982. Dangerous plants. Universe Books, New York.
TIDMARSH, C.E. 1948. Conservation problems of the Karoo. Fmg S. Afr.:
519-530. Pretoria.
TROLLOPE,W.S.W. 1974. Fire as a method of controlling macchia (fynbos)
vegetation on the Amatole mountains of the eastern Cape. Proc. Grass/.
Soc. S. Afr. 8: 35-41.
VAN OUDTSHOORN, F.P. 1991. Gids tot grasse van Suid-Afrika. Briza
Publications, Arcadia, Pretoria.
VAN WYK, S. 1983. 'n Plantekologiese studie van die Abe Bailey-
natuurreservaat. M.Sc. thesis, Potchefstroom University for Christian
Higher Education, Potchefstroom.
VENTER, H.J.T. & JOUBERT, A.M. 1985. Klimplante, bome en struike van
die Oranje-Vrystaat. 2nd ed. P.J. de Villiers, Bloemfontein.
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CHAPTER 7
Vegetation ecology of the southern Free State
Phytosociology of the southern Free State: Overgrazed and
retrogressed vegetation.
171
CHAPTER 7
PHYTOSOCIOLOGY OF THE SOUTHERN FREE STATE: OVERGRAZED
AND RETROGRESSED VEGETATION.
7.1 INTRODUCTION
The fact that Acocks's (1988) broad description of the South African
vegetation is one of the most noted classifications, indicates the necessity
of vegetation classification. Many descriptions of Karoo veld have been
given (Pole-Evans 1936, Potts & Tidmarsh 1937, Adamson 1938, De
Klerk 1947, Werger 1978, Vorster & Roux 1983, Hoffman & Cowling
1990, Bond et al. 1994, Hoffman 1996 a, b, c, d, e, f) of which the
vegetation map by Acocks (1953) is the most detailed. In a description of
the Grassland Biome Project, Mentis & Huntley (1982) stated the
necessity to identify and determine the location and extent of the major
vegetation types and subtypes within the Biome and particularly in the
Upper Nama Karoo (Vegetation type .50), Orange River Nama Karoo
(Vegetation type 51) and the Eastern Mixed Nama Karoo (Vegetation
type 52) (Hoffman 1996).
As very little is known about the phytosociology of the southern Free
State, this description and ecological interpretation of the vegetation
contribute significantly to the. present knowledge of the Grassland Biome
and the results should be useful in compiling a final synecological
synthesis of the Grassland Biome (Scheepers 1986).
The fact that both the Nama-Karoo and Grassland Biomes occur within
the study area indicates a major difference and an overlap of the major
vegetation types (Chapter 2). The biggest part of the area studied lies
within the Nama-Karoo Biome.
The vegetation of the Grassland Biome is physiognomically monolithic
and is characterized by a strong dominance of hemicryptophytes of the
Poaceae while the vegetation of the Karoo-Biome is dominated by
chamaephytes and hemicryptophytes and can be described as grassy,
dwarf shrubland (Edwards 1983). Presently, evidence more likely shows
172
that there has existed a dynamic interface between the Nama-Karoo and
Grassland Biomes, as discussed by Rutherford & Westfall (1994), and
that the concept of a fluctuating boundary between the two biomes,
rather than a replacement of pure grassland by almost pure Nama-Karoo,
is appropriate at least during the last 1 000 years (Avery 1991).
Drought adaptation in plants in the study area happens more through
drought tolerance than through drought avoidance by, for example
storage of water, or through drought evasion. Many of the chamaephytes
are facuitativelv deciduous in response to the high temporal variability of
rainfall (Rutherford & Westfall 1994).
The border between moist and dry grassland is best expressed as
ranging between the 500 and 700 mm rainfall isohyets (Rutherford &
Westfall 1994). Changes in the vegetation relationship with increasing soil
depth suggest that land use, and not climate, has driven the decline of
grasses (Bond et al. 1994). Heavy grazing in the Karoo eliminates the
palatable components, favors generally unpalatable grasses and also
reduces fuel to carry fire (Stuart-Hili & Mentis 1982). According to
Trollope (1980) burning in savanna areas is only practical in situations
where sufficient grass fuel can be accumulated to ensure a high intensity
fire. According to Opperman et al. (1974) Elionurus muticus tends to
increase, and often dominates, under mismanagement of veld. Murray
(1940) found that E. muticus dominated camps that have been grazed
heavily for five years. Opperman et al. (1969) emphasized the necessity
of an early summer rest for both Themeda triandra and Cymbopogon
plurinodis if maximum dry yields are required, while E. lehmanniana
shows a higher resistance to frequent defoliations. Veld management
should thus be applied in relation to the condition of the veld.
The concept of veld condition refers to the condition of the 'vegetation
in relation to some functional characteristics (Trollope et al. 1990).
Droughts in the Karoo areas do not only have an effect on the vegetation,
alone but seriously effects the farming community as a whole, especially
in terms of socio-economic factors. Drouqhts are one of the main factors
responsible for the depopulation of extensive areas and its resultant
effects such as a higher incidence of unemployment, forces the
impoverishment of certain sections of the population.
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Carbon isotope analysis of soil organic matter supports Acocks's
(1988) hypothesis for an increase in shrub cover at the expense of
grasses· across a wide expanse from the central and eastern Karoo
through to the grasslands of the southern Free State (Bond et al. 1994).
Acocks (1988) postulated that the pre-Trekboer veld cover in the Upper
Karoo was dominated by grasses. This veld subsequently deteriorated to
a so-called False Karoo dominated by shrubs (Sampson 1986). According
to Hoffman & Cowling (1990) perennial grass cover has increased in the
Karoo over the last 200 years. They also recorded that many perennial
grasses appeared in greater abundance in 1989 than they did in the
1920's or the early 1960's. The increase in grass cover at these sites has
probably occurred in response. to increased summer rainfall (Hoffman &
Cowling 1990). Tyson et al. (1975), Tyson (1986) and Vogel (1988,
1989) however proposed that the case for progressive desiccation is
untenable. Fluctuations in grass and shrub cover may be temporary or
permanent, depending on grazing treatments and erosion rates (Roux &
Theron 1987). Roux (1966) and Novellie & Strydom (1987), however
suggest that grazing treatment has little effect on the general response of
grasses and shrubs, while Zedler (1981) suggests that in semi-arid
regions, such fluctuations may influence community composition for
decades. According to Avery (1991) the more generalized picture for the
early period suggests that the vegetation cover mainly increased or
decreased as a whole, rather than that grass and scrub cover periodically
replaced each other either in whole or in part.
For successful propagation by seed, grass plants require an adequate
time of unhampered growth for the completion of the reproductive
process. This reproductive process extends from the time of elongation
of the stem bearing the reproductive primordia until the seedling has
become established. In the case of rooigras (Themeda triandra) this period
may extend from March in one year to December the next year - a period
of 21 months. For most grasses, however, a shorter period is sufficient
(Edwards 1972).
Because veld varies considerably from farm to farm and even within
each farm boundary, it is unlikely that anyone grazing system will meet
with optimum success under all conditions in any given area. For
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174
domestic livestock, especially in arid environments, water is a major
limiting factor for survival and growth. Since water is usually available at
only a few scattered point sources, these become the main foci of animal
activities. The result is a zone of attenuating animal impact away from
each watering point - a zone commonly known as the piosphere (Andrew
1988). Andrew (1988) further postulated that the piosphere has been a
particularly useful framework for examining the effects of domestic
livestock on ecological variables. However, if the natural characteristics of
each unit of veld are taken into consideration, it should be possible, with
the aid of the principles of veld management, to develop a beneficial veld
management plan for any area. In order to do this it is necessary to
classify and evaluate the veld on each farm. There is no standard recipe
for veld management, but it is fundamental that any system is dependent
for its success in the first instance on the basic subdivision of the veld
into uniform units and secondly on adherence to the current carrying
capacity of the veld (Edwards 1972). Because seasonal fluctuations are
real events with possible long-term implication, Hoffman & Cowling
(1990) recommended that a more meaningful approach to understanding
vegetation change in the Karoo is to address questions such as:
(1) What happens to the shrubs when grass cover increases in -response
to summer rain?;
(2) Do these two growth forms compete for reeourses or do grasses
merely occupy space not utilized by shrubs?;
(3) Which grasses respond to which rainfall events?; -
(4) Is the increased cover a result of new recruits or increased tussock
size or both?; and
(5) How long do new recruits remain in the community?
Perhaps the most pressing need is to attempt to uncouple
environmental (such as rainfall, temperature) from biotic (such as grazing)
determinants of vegetation change. Although Roux (1966), Donaldson
(1986) and Novellie & Strydom (1987) provides many useful insights, no
general _predictive model incorporating both environmental and biotic
agents of vegetation change has emerged. Perhaps a first step is to
acknowledge that the potentially dynamic seasonal response of grasses
and shrubs is a vital component of any model seeking to explain long-term
vegetation change in the Karoo. To date, this view has been largely
175
ignored as the theory of an expanding Karoo attests (Hoffman & Cowling
1990).
7.2 STRATIFICATION
In a series of maps, Acocks (1953) postulated a major transformation
from grasslands to karroid shrublands from the pre-European era (AD
1400) to the present. According to Fuls (1993), karroid shrubs as well as
signs of Karoo invasion were quite often encountered in areas to the west
of the 650 mm rainfall isohyet in the northern Free State. Le Roux (1978),
however, indicated that rainfall as a proportion of evaporation is more
significant than rainfall isohyet in influencing the distribution of pans. The
30% isoline was thus used as a first stratification of the study area. The
area west of this 30% isoline is considered to be the driest and therefore
has the most impoverished vegetation in the southern Free State (Figure
7.1) .
7.3 STUDY AREA
The study area comprises the western and south-western part of the
southern Free State and is situated west of the 30% isoline (Figure 7.1).
A detailed description of the physical environment was given elsewhere in
this dissertation '(Chapter 2).
GEOLOGY AND SOILS
The study area is underlain by the Karoo System and Ecca & Beaufort
Formations dominate the area. The Ecca Group mainly consists of shale.
Red mudstone commonly occurs in the Beaufort, but is absent in the
Ecca. The latter is dark-grey and carbon-rich. Layers of sandstone
commonly occur within the Beaufort, but seldom in the Ecca. Intrusive
Karoo dolerite frequently occurs. It is mechanically very hard, but
unstable against chemical weathering (Eloff 1984).
176
According to Du Toit (1954) the soils are mainly desert soils with
some Kalahari and Solonetic soils. The main soil forms are Mispah,
Glenrosa, Hutton, Sterkspruit, Swartland and Valsrivier which generally
occur on the plains and low hills, while the Dundee and Oakleaf soil forms
are prominent in the watercourses. The soils are generally alkaline (pH 7,Q
to 8,3) and shallow, especially on the plains and low hills. Soil depth has
a profound effect on the distribution and productivity of the vegetation
(Vorster & Roux 1983).
Many of the soils of the study area are easily eroded by water and
wind. Where vegetation cover has been reduced by persistent
overgrazing, erosion of soils has reached an advanced level of
degradation. Where the sand veneer of some arid areas is eroded away,
dwarf shrubs invade (Tinley 1977).
7.4 METHODS
Relevés were compiled in 89 sample plots. Stratification was based on
rainfall as a proportion of evaporation, topography, aspect and geology.
Plot sizes were fixed at 16 m2 in accordance with Scheepers (1975), .
Bredenkamp & Theron (1978), Bezuidenhout & Bredenkamp (1990) and
Bezuidenhout et al. (1993). In each sample plot, the cover-abundance of
all species was recorded using the Braun-Blanquet scale (Mueller-Dombois
& Ellenberg 1974). Other environmental variables which was recorded
include soil type, land type, rockiness of the soil surface, erosion and
degree of utilization by herbivores.
Two-way indicator species analysis (TWINSPAN) (Hill 1979 a) was
applied to the floristic data set in order to derive a first approximation of
the vegetation units of the area. Refinement was done by the application
of Braun-Blanquet procedures and resulted in a phytosociological table
(Table 7.1).
In order to determine possible vegetation gradients and the pattern of
the plant communities on this gradient, the multivariate ordination
technique, Detrended Correspondence Analysis (DECORANA) (Hill 1979
a) was applied to the floristic data set.
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Taxa names conform to those of Arnold & De Wet (1993).
7.5 RESULTS AND DISCUSSION
In general the vegetation of the overgrazed areas in the southern Free
State can be considered as a Chrysocoma ei/iata - Pentzia g/obosa short
closed shrubland (Edwards 1983). The vegetation is generally utilized as
pasture for cattle and sheep. Most of the pasture is overgrazed and
trampled. The Karoo encroacher species, Chrysocoma ei/iata, is a typical
karraid dwarf shrub and is considered to be an important element of
Karoo invasion in the Grassland Biome (Du Preez 1979).
The species listed in species -group Land R (Table 7.1) are
characteristic of overgrazed -or selectively grazed, degraded vegetation.
The poor condition of the vegetation is emphasized by the presence of
karroid shrubs such as Pentzia g/obosa, Lycium cinereum, Metotobium
eendieens. Wa/afrida saxati/is, as well as the grasses Eragrostis
/ehmanniana, E. obtusa and Fingerhuthia africana, usually associated with
disturbed and trampled soil (Acocks ,.979).
Most of the plant communities encountered have a low species
diversity. The plant communities distinguished in the study area can be
classified in a hierarchy as follows:
1 Lycium cinereum-Sa/so/a g/abrescens Major Community
1.1 Protasparagus capensis-Eriocepha/us spineseens Community
1.1.1 Panicum coloreturn-Feliele fi/ifo/ia Sub-community
1.1.2 Aristida canescens-Osteospermum spineseens Sub-community
1.2 Scirpus dioicus-L ycium cinereum Community
1.2.1 Juncus kraussii-Eragrostis echinoch/oidea Sub-community
1.2.2 Sporobo/us ioc/ados-Scirpus dioicus Sub-community
1.3 Ruschia rigida-Protasparagus suaveo/ens Sub-community
178
1.4 Eriocephalus ericoides-Chrysocoma ciliata Community
1.4.1 Lightfootia albens-Eriocephalus ericoides Sub-community
1.4.2 Lightfootia nodosa-Chrysocoma ciliata Sub-community
1.4.3 Eriocephalus ericoides-Melolobium candicans Sub-community
1.5 Salsola glabrescens-Fingerhuthia africana Community
1.5.1 Galenia africana-Hertia pal/ens Sub-community
1.5.2 Hertie pal/ens-Pentzia globosa Sub-community
1.6 Rhigozum trichotomum-Stipagrostis obtusa Community
2 Chrysocoma ciliata-Aristida congesta Major Community
2.1 Stipagrostis ciliata-Aristida diffusa Community
2.2 Felicia muricata-Eragrostis lehmanniana Community
2.3 Eragrostis superba-Eragrostis lehmanniana Community
2.4 Asclepias fruticosa-Salsola kali Community
DESCRIPTION OF THE PLANT COMMUNITIES
The floristic and associated environmental attributes of the respective
plant communities are as follows:
1 Lycium cinereum-Salsola glabrescens Major Community
This major community was encountered on midslopes and low-lying areas
in the southern Free State. A great variety of soil types are present and
vary from sandy to clayish to rocky soils. The long-term utilization by I
herbivores was subjectively rated as extremely severe. I
I
1
The Lycium cinereum-Salsola glabrescens Major Community is I
differentiated by the two mentioned species, listed in species group N
(Table 7.1). Also conspicuous through the entire major community are the I
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Karoo bush, Pentzia g/obosa and the grasses, Eragrostis /ehmanniana, E.
obtusa and Fingerhuthia africana (species group R, Table 7.1). Panicum
cotoretum (species group A), Scirpus dioicus (species group F), Ruschia
rigida (species group G), Chrysocoma ciliata and Hertia pal/ens (species
group L) have restricted dominances (Table 7.1).
Six distinct communities, subdivided into nine sub-communities were
recognized (Table 7.1).
1.1 Protasparagus capensis-Eriocepha/us spineseens Community
This plant community is predominantly associated with the dry
bottomland and midslopes of hills. Estcourt, Sterkspruit, Swartland and
Valsrivier, soil forms, generally with a clay content of 15-35% (Soil
Classification Working Group 1991) are common.
The soil is sandy-rocky with loose gravel occurring on the soil surface.
The long-term utilization by herbivores was subjectively rated as
extremely severe.
The karroid dwarf shrub, Eriocepha/us spineseens, the spinose
Protasparagus capensis and the Karoo bush Pentzie incana (species group
C, Table 7.1) characterize this plant community. E. spineseens can
survive extremely dry conditions and mainly occurs in the zone between
typical Karoo veld and dry grassland. This species is furthermore primarily
associated with pasture degradation (Anonymous 1968). Also prominent
are Lycium cinereum (species group N) and Pentzia g/obosa (species
group R). P. g/obosa is according to Anonymous (1968) dominant in the
Great Karoo and less prominent in areas adjacent to sweet grassland.
Two distinct sub-communities are distinguishable (Table 7.1).
1.1.1 Panicum cotoretum-Feltcie fi/ifo/ia Sub-community
A sub-community which is restricted to the sandy deposits on the
midslopes of low hills. This vegetation unit is moderately disturbed and is
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180
characterized by the presence of only a few species with Panicum
coloratum (species group A) the most important. The presence of Pentzia
g/obosa (species group R) and Aristida congesta (species group T) is
further indicative of overqrazed and trampled areas (Van Oudtshoorn
1991) .
An average of eight species per relevé was recorded (Table 7.1).
1.1.2 Aristida canescens-Osteospermum spineseens Sub-community
The Aristida canescens-Osteospermum spineseens Sub-community occurs
on rocky areas of the midslopes. The soils are shallow « 100 mm deep),
of the Mispah form and mainly consist of hard rock layers, have a low
clay content (> 40%) and a non-calcareous A-horizon (Soil Classification
Working Group 1991).
The grass, Aristida canescens, is the most conspicuous among the
differentiating species (species group B, Table 7.1). Other species present
include the shrub, Lycium cinereum (species group N), karroid shrub,
Pentzia g/obosa and the grass, Eragrostis /ehmanniana (species group R).
Panicum cotoretum (species group A) and Eriocephalus spinescens
(species group C) have lower cover-abundance values than in the
Panicum cotoretum-Felicie ti/ito/ia Sub-community, but Lycium cinereum
(species group N) is more abundant. Also conspicuous are Osteospermum
spinescens, Ruschia hamata (species group B) and Eragrostis /ehmanniana
(species group R) which are absent in the Panicum coloretum-Felicie
ti/ito/ia Sub-community (Table 7.1). O. spin escens , commonly known as
"Draaibos", is conspicuous in the central Karoo in brackish soil types.
This species is regarded as unpatatable to sheep, but is more readily
utilized by cattle in extreme dry regions. The presence of this species is
normally indicative of a shallow water table (Anonymous 1968) .
.On average, ten species/relevé were recorded for this sub-community
(Table 7.1).
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1.2 Scirpus dioicus-Lycium cinereum Community
This Scirpus dioicus-Lycium cinereum Community is associated with
relativelv wet, low-lying drainage channels of the Db land type in the
south-eastern corner of the study area. The soils are clayey, brackish and
poorly drained.
Species listed in species group F differentiate this community (Table
7.1). Scirpus dioicus (species group F) dominates the vegetation and
Sporobo/us ioc/ados (species group D) only has a restricted dominance
(Table 7.1). Lycium cinereum (species group N), also with a restricted
dominance, is the only abundant shrub. Helichrysum pentzioides (species
group F), commonly known as "Kerriebos", occurs widespread in the
Karoo areas, but is more conspicuous in the western regions. This species
is seldom dominant in karroid areas.and is virtually restricted to low-lying
areas (Anonymous 1968).
Two sub-communities are distinguishable in this vegetation unit (Table
7.1 ).
1.2.1 Juncus kraussii-Eragrostis echinoch/oidea Sub-community
An entity found on marginally moist soils of the lowlands where the
vegetation is overgrazed. The soil is often trampled, especially near
watering points for cattle and dams. The sedge, Scirpus dioicus (species
group F), is characteristically dominant. The differentiating species are
listed in species group E (Table 7.1) of which another sedge, Juncus
kraussii, is the most abundant. Other abundant species are the karroid
shrub Lycium cinereum (species group N) and the grass Eragrostis
/ehmanniana (species group R, Table 7.1).
An average of ten species/relevé was encountered (Table 7.1).
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1.2.2 Sporobo/us ioctedos-Scirpus dioicus Sub-community
This retrogressed plant community was encountered in the low-lying
areas with brackish soils bordering pans. The vegetation is heavily
overgrazed and the soil surface is severely trampled. No exclusive
diagnostic species occur and the sub-community is characterised by the
absence of species from species group E (Table 7.1). The vegetation is
dominated by Scirpus dioicus and the small grass, Sporobo/us ioc/ados
(species group 0, Table 7.1). Although not abundant, He/ichrysum
pentzioides (species group Fl, Lycium cinereum (species group N) and
Pentzia g/obosa (species group R) are also present (Table 7.1) - a sure
sign of pasture degradation.
This sub-community comprises only ten species with an average of 7
species/relevé (Table 7.1).
1.3 Ruschia rigida-Protasparagus suaveo/ens Sub-community
The Ruschia rigida-Protasparagus suaveolens Sub-community is restricted
to the moderately wet drainage lines along public roads; The soil is
clayey. Gravel and stones cover the soil surface. The clay content of the
B-horizon varies from 15-50% (Land Type Survey Staff, in press). Long-
term utilization by herbivores was subjectively rated as moderately severe
to severe.
Ruschia rigida, Protasparagus suaveolens and Flaveria bidentis (species
group G) are the differentiating species. Besides the dominance of
Ruschia rigida, the dwarf shrubs, Eriocephalus ericoides (species group J)
and the Karoo bush Pentzie globosa (species group R) are the most
important (Table 7.1).
1.4 Eriocephalus ericoides-Chrysocoma ciliata Community
The Eriocephalus ericoides-Chrysocoma ciliata karroid dwarf shrub
community is primarily associated with calcareous-rocky soils in low-lying
areas, especially in drainage channels. Pieces of fine gravel and
183
calcareous stones occur on the surface. The vegetation is selectively and
patchily overgrazed and the soil surface trampled.
This .community is differentiated by the combined presences of
Eriocepha/us ericoides (species group J), Chrysocoma ei/iata and Hertia
pal/ens (species group L, Table 7.1). E. ericoides, commonly known as
"Kapokbos", is only locally prominent. This species inhibits the growth of
"sweet grasses" (Anonymous 1968) and is often extremely abundant in
very dry bottomland situations. It can absorb water through its leaves and
is drought resistant (Anonymous 1968). Chrysocoma ei/iata and Hertia
pal/ens (species group L) are also drought-resistant and widely dispersed
throughout this plant community (Table 7.1). The presence of
Chrysocoma ei/iata and Pentzia .g/obosa (species group R) is indicative of
overgrazing and habitat disturbance (Anonymous 1968). According to
Anonymous (1968), C. ciliata is unpalatable and deqenerates in an area
well covered with grasses. Species indicative of degradation occur in
places throughout this vegetation unit.
Three . distinct sub-communities further differentiate this plant
community (Table 7.1).
1.4.1 Lightfootia a/bens-Eriocepha/us ericoides Sub-community
This sub-community is typically found on the well-drained flat areas in
drainage channels along public roads in the south-western Free State. The
soil easily dries out and is of a clayey-calcareous nature. A high
percentage of the soil surface is covered by calcareous stones.
Lightfootia a/bens (species group H) is diagnostic of this sub-
community. The low cover-abundance of Eriocepha/us ericoides (species
group J, Table 7.1) as well as the higher cover-abundance of Chrysocoma
ei/iata (species group L) also differentiate this sub-community. According
to Anonymous (1968), C. ciliata, can be seen as one of the most
important and active. invaders of overgrazed and trampled grassland. It
can be seen as the leading species of Karoo invasion and increases in
overgrazed pasture (Anonymous 1968).
184
An average of seven species/relevé was recorded (Table 7.1).
1.4.2 Lightfootia nodosa-Chrysocoma ei/iata Sub-community
This sub-community occurs where a sandy deposit overlies the calcareous
soils, especially in drainage channels and eroded areas. Doleritic and
sandstone rocks occur on the surface.
Lightfootia nodosa (species group I) is the differentiating species which
distinguishes this vegetation unit from the rest of the Eriocepha/us
ericoides-Chrysocoma ei/iata Community (Table 7.1). The absence of
Lightfootia a/bens differentiates this sub-community from the Lightfootia
a/bens-Eriocepha/us ericoides Sub-community (Table 7.1). The Lightfootia
nodosa-Chrysocoma ciliata Sub-community has a low species diversity of
only eleven species, with only Lightfootia nodosa (species group I),
Eriocepha/us ericoides (species group J) and Chrysocoma ei/iata (species
group L) occurring regularly (Table 7.1).
An average of five species/relevé was recorded (Table 7.1).
1.4.3 Eriocepha/us ericoides-Metotobium candicans Sub-community
The Eriocepha/us ericoides-Metotobium candicans Sub-community is
mostly associated with disturbed and eroded areas in the southern parts
of the study area, west of Luckhoff. These areas are mostly disturbed due
to continuous overgrazing. Duplex soils with red B-horizons are the most
prominent with red apedal soils « 300 mm deep) also frequently
occurring (Land Type Survey Staff, in press). Hutton and Glenrosa soil
forms are the most prominent (Land Type Survey Staff, in press).
Of the 12 species encountered in this, sub-community, none was
diagnostic. This sub-community is recognized by - the absence of
Lightfootia a/bens and L. nodosa. Apart from Eriocepha/us ericoides
(species group J) and Hertia pal/ens (species group L), Metolobium
candicans, Chrysocoma ciliata (species group L) and Eragrostis obtusa
(species group R) are the most prominent species. The presence of C.
185
ciliata, especially is a definite sign of pasture degradation (Anonymous
1968). Salsola glabrescens (species group N) was recorded in only one
plot, but was dominant (Table 7.1).
1.5 Salsola glabrescens-Fingerhuthia africana Community
The Salsola glabrescens-Fingerhuthia africana Community represents
overgrazed and trampled areas on bottomland situations of the Ae land
type in the southern Free State.
This vegetation type is differentiated by the constant presence of
Hertia pal/ens and Chrysocoma ciliata (species group L). Pentzia globosa,
Eragrostis lehmanniana and Fingerhuthia africana (species group R) are
also important members. A total of 23 species were listed. The majority
are typical karroid species. Only 5 grass species were listed - a clear
indication of retrogressed habitat conditions (Vorster & Roux 1983). The
absence of Eriocephalus ericoides differentiates it from the Eriocephalus
ericoides-Chrysocoma ciliata Community.
Two distinct sub-communities further divide -this community (Table
7.1) .
1.5.1 Galenia africana-Hertia pal/ens Sub-community
The Galenia africana-Hertia pal/ens Sub-community is strongly associated
with the rocky dolomite areas in and around sink holes. Soil types often
associated with this vegetation unit include Hutton, Glenrosa, Oakleaf and -
Swartland (Land Type Survey Staff, in press). These soils are
predominantly sandy with red B-horizons. The trampling effect of
livestock is evident. Ant heaps are prominent.
Galenia etricene (species group K, Table 7.1 l dominates the vegetation
and is the only diagnostic species present. Other regularly occurring
species include the co-dominant Hertia pal/ens, Cbrvsocome ciliata
(species group L), Lycium cinereum, Salsola glabrescens (species group
Nl and the grasses Eragrostis lehmanniana and Fingerhuthia africana
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(species group R, Table 7.1). Hertie pal/ens, commonly known as
"Springbokbos" , is completely worthless as pasturage and also
unpalatable. Under severely degraded conditions it may cause poisoning
and especially affects the liver of livestock (Anonymous 1968).
An average of seven species/relevé was recorded (Table 7.1).
1.5.2 Hertia pallens-Pentzia globosa Sub-community
The Hertia pal/ens-Pentzia globosa Sub-community is primarily associated
with red soils of high base status. The soils are generally deeper than 300
mm and no dunes occur. Inanda, Kranskop, Magwa, Hutton, Griffin and
Clovelly soils are prominent (Land Type Survey Staff, in press). An
average clay content of 35-55% is common (Soil Classification Working
Group 1991). No ant or termite heaps were spotted.
This sub-community lacks diagnostic species and is recognized by the
total absence of Galenia africana (species group K) and the scanty
occurrence of Lycium cinereum (species group N, Table 7.1). Also
noteworthy are the absences of Walafrida sexstins and Melolobium
candicans (species group L). Although six species of grass were listed,
these are poorly represented. The most important species are Eragrostis
lehmanniana, E. obtuse, and Fingerhuthia africana (species group R, Table
7.1). The high cover-abundance of particularly the dwarf shrub
Chrysocoma ciliata (species group L) is a definite sign of pasture
degradation (Anonymous 1968). Walafrida saxatilis (species group L),
Salsola glabrescens (species group N) and Pentzia globosa (species group
R) are the most abundant other karroid dwarf shrubs present (Table 7.1).
P. globosa, commonly known as "Bitterkaroo", randomly occurs in the
boundary zone between dry grasslands and karroid areas (Anonymous
1968).
On average, six species/relevé were recorded for this sub-community
(Table 7.1).
187
1.6 Rhigozum trichotomum-Stipagrostis obtusa Community
This tall closed shrubland was encountered on the bottomlands and
footslopes of hills. These areas, mainly in the western and south-western
parts, are often overgrazed and trampled. The Ag-, Ae- and Da land types
are the most prominent. The soils are primarily red, having a high base
status" Duplex soils with red B-horizons are also present (Da land type).
Inanda, Kranskop, Magwa, Hutton, Griffin and Clovelly soils, all having a
generally high clay content (15-35% clay, Soil Classification Working
Group 1991) are the most prominent (Land type Survey Staff, in press).
Bezuidenhout (1995) described a similar community in the Vaalbos
National Park on moderately deep, poorly drained, aeolian sands.
According to him, the tree stratum is poorly developed with a canopy
cover of 2%. Trees are absent, probably due to the low rainfall .
. The shrub, Rhigozum trichotomum (species group M), is dominant
over large areas of trampled veld in the Free State (Venter & Joubert
1985) and, together with Stipagrostis obtusa, constitute the
differentiating species of this community (Table 7.1). According to
Acocks (1979) the dominance of R. trichotomum is restricted to the
southern variation of the False Arid Karoo and that this condition of
dominance is artificial, resulting from elimination of effective competition
by grasses. Acocks (1988) described the Rhigozum trichotomum Veld of
the Plains under the Orange River Broken Veld (Veld type 32) on gravelly
and stony plains. At the upper margin of the Orange River Broken Veld,
where it merges into the Arid Karoo, this may be the only shrub present,
but, as a rule, it is accompanied by a few other shrub species. R.
trichotomum sometimes forms dense growths and is sometimes scattered,
but usually tend to spread into clumps by means of its stolons (Acocks
1988). In sandy valleys it grows up to two metres tall, but is usually only
one metre tall. Other widely distributed species include the shrub, Lycium
cinereum, the dwarf shrub, Salsola glabrescens (species group N) and the
Karoo encroacher Chrysocoma ciliata (species group L, Table 7.1).
Stipagrostis obtusa (species group M), commonly known as fine "Twaa"
by Bushmen, (Van der Walt 1993) is the only noteworthy grass present
(Table 7.1). According to Van der Wait (1993), S. obtusa is commonly
known as the pioneer of the sandy areas of the Kalahari.
188
Twenty species were listed for this community with an average of six
species/relevé (Table 7.1).
2 Chrysocoma ciliata-Aristida congesta Major Community
This major community was encountered on low-lying areas in the
southern Free State. A great variety of soil types are present and vary
from sandy to clayish soils. The long-term utilization by herbivores was
subjectively rated as extremely severe.
The Chrysocoma ciliata-Aristida congesta Major Community is
differentiated by the stronger. presence of Aristida congesta (species
group T, Table 7.1). Trees and shrubs were found to be totally absent.
The restricted dominance of Stipagrostis ciliata (species group 0) is
conspicuous,· espeCially in the. sandy areas. The dwarf .shrubs
Chrysocoma ciliata, .Hertia pa/lens, .Walafrida saxatilis (species group L),
as well as the grasses Eragrostis lehmanniana and E. obtusa (species
group R) occur widespread (Table 7.1).
Four distinct communities were identified (Table 7.1).
2.1 Stipagrostis ciliata-Aristida diffusa Community
The Stipagrostis ciliata-Aristida diffusa Community is associated with the
dry law-lying sandy deposits of the Ag land type near Petrusville in the
south-western part of the study area. A thick layer of sand (100-200 mm
thick) covers the rocky soil surface (duplex soils). Wind erosion often is a
common phenomenon, especially in the unprotected lowlands.
This grassland is dominated by bushmen-grass, Stipagrostis ciliata
(species group 0), a valuable sweet grass in the arid areas. According to
Van der Wait (1993), bushmen-grassveld is our only true grassland,
because it is independent of fire for survival. S. ciliata, commonly known
as granular "Twaa" among Bushmen, is a highly palatable species and
commonly occurs in areas with an average rainfall of less than 150 mm.
per annum (Van der Wait 1993). Other graminoids are scarce and
189
restricted to the somewhat patchy occurrences of Aristida diffusa
(species group 0), Eragrostis lehmanniana (species group R) and Aristida
congesta (species group T, Table 7.1), a clear indication of the
retrogressed condition of the veld.
An average of six species/relevé was recorded (Table 7.1).
2.2 Felicia muricata-Eragrostis lehmanniana Community
The Felicia muricata-Eragrostis lehmanniana Community is primarily a
disturbed, overgrazed grassveld on the edges of pans where the clay
content can vary considerably (15-55%, Soil Classification Working Group
1991). The soil surface is rocky and trampled. No sandy layer occurs and
the habitat conditions are drier than in the Stipagrostis ciliata-Aristida
diffusa Community.
This community lacks exclusive diagnostic or character species, but is
rather characterized by the presence and often dominance of the grasses
Eragrostis lehmanniana (species group R) and Aristida congesta (species
group T), as well as the constant occurrence of Felicia muricata (species
group P). Noteworthy is the virtual absence of Stipagrostis ciliata (species
group 0) from this community, probably due to the less sandy habitat.
Eragrostis superba (species group a) is absent in this community (Table
7.1). Although a strong grass component exists, Karoo elements such as
Felicia filifolia (species group A), Protasparagus suaveolens (species group
G), Chrysocoma ciliata, Walafrida saxatilis (species group L) are also
present (Table 7.1).
On average, six species/relevé were recorded for this community
(Table 7.1).
2.3 Eragrostis superba-Eragrostis lehmanniana Community
The Eragrostis superba-Eragrostis lehmanniana Community is found on
sandy to clayey soils in drainage channels throughout the entire study
area. These soils are often extremely rocky.
190
According to Van Oudtshoorn (1991), Eragrostis superba prefers
sandy and rocky soil, but also grows in turfish soil. Eragrostis superba
(species group Q), a nutritious grazing grass, differentiates this
community and is the only widely dispersed species often forming dense
stands in association with Chrysocoma ciliata, Walafrida saxatilis (species
group L), Eragrostis lehmanniana (species group Rl and Aristida congesta
(species group Tl. Salsola kali (species group S) only has a restricted
dominance (Table 7.1).
An average of only four species/relevé was recorded (Table 7.1).
2.4 Asclepias fruticosa-Salsola kali Community
The Asclepias fruticosa-Salsola kali Community is associated with
severely degraded and disturbed areas in drainage channels along public
roads. The soils are clayey and calcareous stones occur on the surface.
The habitat is wetter than in the Eragrostis superba-Eragrostis
lehmanniana Community.
The unpalatable forb, Asclepias fruticosa (species group S), which
grows to about 1.5 m tall, is the only abundant species present. A.
fruticosa occurs widespread in South Africa and is virtually restricted to
sandy river courses, disturbed sandy soils, sandy bottomland situations,
Quicksand and along public roads (Anonymous 1968). Salsola kali and
Tagetes minuta (species group S), both exotics, typical in overgrazed and
trampled veld, together with the "steekgras" , Aristida congesta (species
group T), are the only other species worth mentioning (Table 7.1).
On average, only four species/relevé were recorded (Table 7.1 I.
ORDINATION.
A DCA ordlnatlon (Hill 1979 b) was applied to the floristic data set in
order to determine possible environmental gradients. No clear
discontinuity in the distribution of a number of plant communities exists
191
which is probably due to the overall retrogressed vegetation and disturbed
habitat conditions. Most of the plant communities are poorly represented
by only a few differentiating species and are not always easily
distinguishable in the veld. Severe habitat degradátion, such as erosion
and overgrazing of natural vegetation was evident through the entire
study area. It was thus decided that such an ordination should not
complement the data.
DISCUSSION
The fundamental aspects set out here have primarily a bearing on the
reaction of the vegetal cover to pasture and veld mismanagement. The
removal of young growth of established plants by grazing during their
renewal stages of growth - for example when plants are sprouting at the
beginning of a growth cycle, or after a drought _. results chiefly in
physiological damage to the plant systems. This damage mainly includes
the disruption and weakening of the vital processes and their activity, and
especially exhaustion and weakening of the root system. Physiological
damage to plants can also take place with grazing during the termination
of their growth cycles when, for example, the replenishment of the root
reserves of the plant takes place, which is essential for rapid and vigorous
regrowth at the start of a new cycle (Hugo 1968).
In sweet grassveld, the most important adverse changes in the veld
during the period of European settlement have been: (a) a reduction in
total vegetal cover, causing high runoff and erosion; (b) a replacement of
nutritious perennial grasses by inferior annual grasses and weeds; and (c)
the increase of woody weeds, notably species of Acacia, Chrysocoma
and Pentzia (Tainton 1984).
Grazing during the active growth stages of a plant results in vegetative
damage and destruction of plant material. This can lead, in severe cases,
to the complete absence of ecologically important plant species and thus
seriously affects the whole environment by the invasion of ecologically
less important species. This is clearly illustrated in the presence of species
such as Hertia pal/ens, Lycium cinereum, the Karoo encroacher,
Chrysocoma ciliata, Pentzia globosa, as well as the grasses Aristida
192
congesta and Eragrostis lehmanniana. Trees and shrubs are virtually
absent and are restricted to the patchy occurrences of Rhigozum
trichotomum. This fact is supported by Van den Berg et al. (1975) who
found that autumn grazing (when the seeds of climax grasses ripen) was
the most detrimental in terms of the basal cover of climax grasses in the
Cymbopogon- Themeda veld, while both spring and winter grazing resulted
in only small detrimental changes in the vegetation. They also found that
summer and autumn grazing resulted in much smaller climax grass tufts
than those of spring and winter grazing. According to them, this decline
in basal cover could thus be attributed mainly to a reduction in tuft size.
The tuft size of pioneer grasses,' however, remained reasonably constant
during all the seasons (Van den Berg et al. 1975). According to them, an
increase in basal cover of pioneer grasses could be attributed largely to
the increase in the tuft density of pioneer grasses. According to Hoffman
et al. (1990) an increase in grass basal cover may negatively influence
shrub basal cover. They also suggest that a large increase in summer rain,
relative to the tong-term mean, would result in an associated increase in
the percentage change in grass basal cover (Hoffman et al. 1990). It
should, however, be kept in mind that various other environmental
factors, such as light intensity, temperature etc. are also involved in
vegetation changes (Hoffman et al. 1990).
According to Hugo (1968) unpalatable grasses such as Elionurus
muticus and Eragrostis plana often' invade the veld under selective
grazing. Animals concentrate on the palatable grasses which are
consequently continually grazed short, lose their vigor and, as a result,
use less plant food and water. These nutrients are then available for use
by unpalatable types which thrive there and begin to dominate the veld.
Roberts (1974) reported that large areas in the Willem Pretorius Game
Reserve were changing to Karooveld as a result of the concentration of
animals on certain areas of the reserve. He also noted the possibility of
extensive future erosion if the situation is left unchanged. Resting of the
eroded Karooveld during the growing season was considered to be of the
utmost importance to allow recuperation of this potentially valuable
grazing land (Roberts 1974).
If this condition is allowed to develop, it is extremely difficult and
sometimes virtually impossible to find a practical way of getting rid of
193
unpalatable species. This is why it is of the utmost importance that the
veld should always be carefully managed. Certain unpalatable grass types
such as Cymbopogon spp., however, represent different successional
stages and may be removed by judicious application of veld management
practices (Hugo 1968).
There are various management systems which give recognition to the
principles of sour-veld management. It should, however, always be kept
in mind that management systems (camp systems) aim at bringing about
soil and veld stability under utilization conditions. Since soil and veld
stability are also a function of the climate and the latter (rainfall in
particular) varies from season to season and even within seasons, it is
essential that the management be flexible so as to be adaptable to
environmental changes. Factors such as grazing intensity, the number of
rest camps, frequency of the rest periods and veld burning will require
continual adjustment. At present, so-called multi-camp, open-rotation
grazing systems are being propagated under widely divergent conditions.
According to Grunow (1973) the object is to adapt to erratic rainfall,
variable environment, veld _condition and growth rate of the most
important grazing grasses (indicator grasses). In very dry areas the
management system tries to make provision for the resting of certain
camps after rain, so that maximum benefit may be derived from the rest
period during which various essential physiological processes take place
(Grunow 1973). Grunow (1973) proposed three general methods for
increasing the production of, "natural" veld as a resource of feed for
herbivores. These are by feld fertilization, by reinforcement with legumes
and more productive grasses, and by veld replacement with better grass
and legume species.
In situations where the undesirable grass species is lower in the
grassland succession than the desirable species, controlled selective
grazing is effective in reducing the abundance of the undesirable species.
However, controlled selective grazing is ineffective when the undesirable
grasses is higher in the grassland succession than the desirable species.
Therefore the desirable grass species will always be at a competitive
advantage to the undesirable grasses by -virtue of their higher
successional status and the preferential grazing treatment they receive in
a system of controlled selective grazing (Trollope 1980). Continuous
194
overstocking and overgrazing have affected the dry matter production
potential and stability of veld (Fourie 1983) and, inevitably, animal
production. Therefore, to maintain the livelihood of many South African
farmers, efforts to stop the retrogression of veld and to increase the
utilization to that of its full potential should be considered as top priority
(DeWaal 1986).
According to Vogel (1994) drought initiatives today are not markedly
different from those of the past. The National Drought Committee still
focuses its drought-relief efforts primarily on the livestock farmers. The
most recent drought saw the usual crisis-driven response, with vast sums
of money being diverted to assist debt-ridden farmers, the installation and
repair of inadequate water supplies in rural areas, and the intensification
of food-aid schemes, often poorly targeted.
Finally it may be added that plant succession goes hand in hand with
soil changes. The development from the pioneer condition to the climax
condition is accompanied by the general building up and improvement of
the soil (higher moisture and nutrient status), while changes from the
climax to the pioneer condition are accompanied by general deterioration
and loss of soil. Soil, subject to erosion, or soil which has lost its
structure, will cause plant succession to progress very slowly and so
delay the whole process of veld improvement. Soil stability therefore
forms one of the corner-stones of veld-pasture production (Hugo 1968).·
According to Morgan (1986), soil management is concerned with ways of
preparing the soil to promote dense vegetation growth and improve its
structure so that it is more resistant to erosion. Soil conservation must be
based on the following:
(a) covering the soil to protect it from raindrop impact;
(b) improving the aggregate stability of the soil; and
(c) increasing surface roughness to reduce the velocity of runoff and wind
(Morgan 1986).
Attempts to redress some of these problems. resulted in the torrnatien
of the National Consultative Forum on Drought (Adams 1993 and Hobson
& Short 1993) in June 1993. Attempts to formulate a comprehensive
national early warning system, that focuses both on the physical and
human indicators, including weather prediction and monitoring, water
195
supply, health and nutrition, are being made (Waiters 1993) and it is
hoped that these will succeed in establishing an effective hazard-
management plan. The expertise for an early warning system exists, but it
needs to be co-ordinated, clearly targeted, interactive and given greater
authority to be effective.
196
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204
CHAPTER 8
Vegetation ecology of the southern Free State
Vegetation ecology of the southern Free State: Grassland communities
205
CHAPTER 8
VEGETATION ECOLOGY OF THE SOUTHERN FREE STATE:
GRASSLAND COMMUNITIES
8.1 INTRODUCTION
The major factor responsible for large scale natural vegetation changes is
climate, especially rainfall and temperature (Rutherford & Westfall 1994). It
is well documented that radical changes in climate and vegetation has taken
place in South African vegetation in the past (Brooks 1926). In relatively
recent times (50 000 to 12 000 B.P.) climatic change in southern Africa
caused large scale expansions and contractions of Karoo vegetation with
corresponding change in grassland (Van Zinderen-Bakker 1962). From these
former, but gradual changes, it is reasonable to assume that climatic
change, though extremely gradual, is inherent to the Karoo environment. It
is therefore not inappropriate to assume that Karoo vegetation is at present
being affected by a macroclimatic change and mostly towards the
xeromorphic (Van Zinderen-Bakker 1962). Thorough analysis of
meteorological data (50 000 - 12 000 B.P.) showed that no drastic change
in climate could hitherto be statistically identified (Dyer & Tyson 1977).
Vegetation change, as a result of climatic change, can thus be disregarded
for consideration as a factor responsible for detectable changes in Karoo
vegetation. It thus transpires that vegetation change over the last three
centuries can be entirely ascribed to the activities of man and his
agricultural pursuits, especially grazing by sheep (Roux & Opperman 1982).
The tropical elements of Karoo vegetation, mostly grass species, respond
primarily to summer rainfall, while Karoo-bushes respond to autumn and
spring rains (De Klerk 1947). A large number of important species (mostly
those from an agricultural point of view considered as undesirable,
unpalatable and encroaching types) may exhibit growth cycles of a high or
low rate during any season of the year. This partly accounts for the greater
success of these species during any season.
206
The variability of seasonal rainfall, e.g. a higher rainfall for a few
successive summer seasons or alternately the cooler months, evokes
growth responses according to phenological characteristics. The result of
this regulating mechanism is that the physiognomy of Karoo vegetation may
change considerably from grassy to shrub-like. This phenomenon is
particularly noticeable in those types of veld such as the False Upper Karoo
(Veld Type 36, Acocks 1988) where grasses are an important constituent of
the vegetation, e.g. the development of a blanketing cover of Aristida spp.
in 1950, following copious late summer rains, and Eragrostis lehmanniana
occurring extensively in Karoo vegetation in 1975 following the
overabundant rain in 1974 (Roux & Opperman 1982). The Karoo thus avails
over vegetation and environmental elements which are conducive to the
variability and instability of the vegetation. Coupled with the grazing factor,
these characteristics can lead to profound and permanent changes in the
vegetation composition.
The ecologically most important attributes of grasses are:
1. Their ability to cover the ground with a permanent mat of foliage dense
enough to protect it against the eroding action of wind and water, so that a
depth of soil can accumulate and be held by the mass of fibrous roots
possessed by grass. and
2. the fact that it provides the principal food of the grazing animal, whether
wild or domestic ..
When selective grazing ceases, either through complete resting, or,
better through application of an artificial form of non-selective grazing, a
second environment appears, in which such of the pioneer grasses and
climax grasses as have survived are free to try to re-establish a cover on
eroding sub-soil (Acocks 1971). According to McNaughton (1985) selective
grazing improves the nutrient status of regrowing plant tissue. The recycling
of nutrients may be an important component of stimulation of productivity
by grazing (McNaughton 1985).
'---------------------~-------------- - -
207
According to Acocks (1971), Themeda triandra is ecologically the most
important grass, both to the wild animal and to the domestic animal, and the
most widely distributed of the climax dominants. This species has a north-
eastern distribution of tropical and subtropical areas (Pattern 1, Acocks
1971). Danckwerts (1981) found that veld dominated by Themeda triandra
in sweet thornveld areas of the eastern Cape had a higher grazing capacity
than. that dominated by pioneer species like Aristida. A good indicator of the
physiognomic structure of the grass sward is the standing crop of grass as
it describes the volume and density of plant material at ground level.
Continuous grazing throughout the winter period, and even during early
summer, severely damages species such as Themeda triendrs. Eragrostis
curvula and Digitaria eriantha although it does not affect the total herbage
yields (Coetsee 1975).
Sour veld is poorly utilized by animals during winter due to unpalatability
and low feed value (Coetsee 1975). Coetsee (1975) further reports that
grazing in autumn and early summer, tends to give significantly (p < 0.01)
lower basal cover of T. triandra and results in an increase (p < 0.01) of
Cymbopogon plurinodis, while lack of grazing results in a decrease (p <
0.01) 'of C. plurinodis.
Continuous grazing of summer rested veld during the whole winter period
and during early summer causes severe damage to certain species, such as
T. triandra, E. curvula and D. eriantha, while early summer grazing in
particular stimulates undesirable species such as Elionurus muticus and can
result in a very unpalatable sward (Coetsee 1975).
Kruger & Edwards (1972) have done research on the utilization and
relative palatability of different gráss species in the western variation of the'
Bakenveld and found that Eustachys paspaloides and Themeda triandra (in
that order) are the two species which, irrespective of treatment, are the
best utilized.
Evapotranspiration and water use efficiency were determined for each of
seven grass species (Cymbopogon plurinodis, Digitaria eriantha, Eragrostis.
1...- . I
208
eh/orome/as, E. /ehmanniana, Panieum stapfianum, Sporobo/us fimbriatus
and Themeda triandra) by Snyman (1989). According to him the differences
of mean daily evapotranspiration over two years were not statistically
significant. The average aboveground phytomass production and water use
efficiency of C. p/urinodis, D. eriantha and T. triandra was higher (p < 0,01)
than that of the other species. He further concluded that aboveground
phytomass production was the determining factor of water use efficiency.
However, under conditions of moisture stress, the water use efficiency of
these three species was low, with that of Eragrostis eh/orome/as the
highest. Snyman (1989) further -emphasized that water use efficiency in
particular is an important factor in determining the distribution of grasses.
The study of the grasslands of the undulating plains in the southern Free
State forms part of a comprehensive phytosociological research programme
under the Grassland Biome Project (Mentis & Huntley 1982; Scheepers
1986). This paper primarily focuses on the Breun-Blanquet classification and
plant-ecological interpretation of the grassland communities in the southern
Free State. Themeda triandra is, according to Van Oudtshoorn (1991), the
most important grass in South Africa and occurs in all veld types. T. triandra
is evident through the entire -southern Free State and is the differentiating
species (Species Group V, Table 8.1).
8.2 STUDY AREA
In the Upper Orange River Valley, there is a climatic boundary approximately
indicated by the 400 mm rainfall isohyet, which coincides remarkably well
with the borderline between the true Karoo-Namib dwarf shrub
communities, the Pentzietea ineanae, and the more grassy karraid
communities (Werger 1980). The 600 mm rainfall isohyet is indicated in
Figure 8.1. To be in accordance with Chapter 7, the 30% isoline is
considered to be a more accurate stratification of the study area. The area
east of the 30% isoline was thus studied in this survey.
A broad description of the physical environment and major plant
communities of the southern Free State is given elsewhere (Chapter 2).
209
8.3 METHODS
Relevés were compiled in 153 sample plots. Stratification was based on
rainfall as -a proportion of evaporation, topography, aspect and geology.
Severely degraded areas were avoided in this survey. Long-term overgrazed
and retrogressed vegetation is discussed elsewhere in this dissertation
(Chapter 7). Plot sizes were fixed at 16 m2 in accordance with Scheepers
(1975), Bredenkamp & Theron (1978), Bezuidenhout & Bredenkamp (1990)
and Bezuidenhout et al. (1993).
In each sample plot, the cover-abundance of all species was recorded
using the Braun-Blanquet scale (Mueller-Dombois & Ellenberg 1974). Other
environmental variables which was recorded include soil type, soil depth,
land type, rockiness of the soil surface, erosion and degree of utilization by
herbivores.
Two-way indicator species analysis (TWINSPAN) (Hill 1979 b) was
applied to the floristic data set in order to derive a first approximation of the
vegetation units of the area. Refinement was done by the application of
Braun-Blanquet procedures and resulted in a phytosociological table (Table
8.1 ).
In order to determine possible vegetation gradients and the pattern of the
plant communities on this gradient, the multivariate ordination -technique,
Detrended Correspondence Analysis (DECORANA) (Hill 1979 a), was applied
to the floristic data set.
Taxa names conform to those of Arnold & De Wet (1993).
8.4 RESULTS AND DISCUSSION
The grassland of the southern Free State (Table 8.1) can be broadly
classified as the Themeda triendre-Ereqrostis lehmanniana -Grassland.
According to Acocks (1988) overgrazing causes Themeda triandra to be
210
replaced by less .palatable grasses such as, Eragrostis echinochloidea with
little or no reduction in the cover.
The Karoo has nearly overrun the Dry Cymbopogon- Themeda Veld in the
southern Free State and is randomly increasing with time (Acocks 1988).
The grass genera, Themeda, Setaria, Panicum, Eragrostis and Aristida are all
of tropical origin (Acocks 1971) with wide ecological adaptabilities and
therefore occur widespread. Themeda triandra is the most common grass
species in South Africa and is found in all grass veld types of South Africa
but is more common in undisturbed climax veld (Acocks 1988, Gibbs
RusseIl et al. 1990).
The widespread occurrence of grasses such as Aristida congesta and the
karroid shrublets Chrysocoma ciliata and Pentzia globosa is indicative of the
expansion of disturbed veld at the expense of "sweet" grassland (Acocks
1988).
Shrubs and trees are seldomly encountered in the undulating grassland
(Fuls 1993). The most important shrubs encountered include Euclea crispa
subsp. ovata, Rhigozum obovatum and Rhus ciliata, all of which have
patchy occurrences. The dwarf fern, Cheilanthes eckloniana, also has a
patchy occurrence and randomly occurs in rocky habitat (Fuls 1993). All
these woody and ferns species are restricted to areas where rocks occur on
the soil surface. The hills are low, consist of sandstone and dolerite and the
slopes are seldom in excess of four degrees.
CLASSIFICATION
A hierarchical classification of the plant communities of the Themeda
triandra-Eragrostis lehmanniana 'Grassland is as follows:
1 Nidorella resedifolia- Themeda triandra Community
1.1 Panicum schinzii-Salvia disermas Sub-community
1.2 Agrostis lachnantha-Protasparagus suaveolens Sub-community
211
2 Protasparagus laricinus-Felicia filifolia Community
3 Ch/oris virgata- Themeda triandra Community
I
3.1 Xanthium spinosum-Senecio consanguineus Sub-community
3.2 He/ichrysum dregeanum-Urochloa panicoides Sub-community
4 Herpochtoe fa/x-Elionurus muticus Community
5 Eragrostis gummiflua- Themeda triandra Community
5.1 Elionurus muticus- Triraphis andropogonoides Sub-community
5.2 Eragrostis gummiflua-Sporobo/us fimbriatus Sub-community
6 Sporobo/us fimbriatus- Themeda triandra Community
6.1 Cymbopogon plurinodis-Eragrostis curvula Sub-community
6.2 Sporobo/us timortetus-ërearostts lehmanniana Sub-community
7 Cymbopogon p/urinodis- Themeda triandra Community
7.1 Panicum coloratum- Themeda triandra Sub-community
7.2 Themeda triandra-Aristida diffusa Sub-community
8 Heteropogon contortos- Themeda triandra Community
8.1 Cymbopogon p/urinodis-Heteropogon contortus Sub-community
8.2 Heteropogon contortus- Themeda triandra Sub-community
8.3 Enneapogon scoparius-Hermannia vestita Sub-community
8.3.1 Protasparagus striatus-Euclea crispa subsp. ovata Variant
8.3.2 Stachys rugosa-Eustachys paspaloides Variant
9 Rhus cilia ta- Themeda triandra Community
9.1 Heteropogon contortus-Chrysocoma ciliata Sub-community
9.2 Rhus ciliata-Chrysocoma ei/iata Sub-community
10 Euryops empetrifolius-Eriocephalus spineseens Community
11 Digitaria eriantha- Themeda triandra Community
12 Themeda triandra-Eragrostis lehmanniana Community
212
DESCRIPTION OF THE COMMUNITIES
1 Nidorella resedifolia- Themeda triandra Community
This plant community occurs on the low-lying areas of the Ca and Da land
types varying from well-drained to poorly drained soils. The Da land type
consists mainly of duplex soils with red B-horizons while the Ca land type
consists of soils where upland duplex and/or margalitic soils are common.
Estcourt, Sterkspruit, Swartland, Valsrivier and Kroonstad soils are the most
prominent (Land Type Survey Staff, in press). The clay content of the B-
horizon generally varies between 15% and 35% (Macvicar et al. 1977).
Nidorella resedifolia (species group C) differentiates this vegetation unit.
The presence of the small grass, Chloris virgata (species group G) is
indicative of overgrazed conditions (Van Oudtshoorn 1991). The high cover-
abundance for Themeda triandra (species group W) is conspicuous (Table
8.1 ).
Two sub-communities are recognized within this community (Table 8.1).
1.1 Panicum schinzii-Salvia disermas Sub-community
This sub-community is restricted to the marginally overgrazed and trampled
zones on flat bottom lands or flood plains along rivers and streams. Sandy
clay loams are common.
The Panicum schinzii-Salvia disermas Sub-community has a infrequent
occurrence (only three relevés were listed) with Panicum schinzii and Salvia
disermas (species group A) differentiating this vegetation unit (Table 8.1).
Other species are scarce and only the grasses Eragrostis curvula, E. obtusa,
Digitaria eriantha (species group V), Aristida diffusa and Themeda triandra
(species group W) are found in this sub-community (Table 8.1).
An average of seven species/relevé was encountered (Table 8.1).
213
1.2 Agrostis lachnantha-Protasparagus suaveolens Sub-community
The Agrostis lachnantha-Protasparagus suaveolens Sub-community is found
in the lower-lying areas of the Nidorella reseditolie- Themeda triandra
Community, adjacent to drainage channels. The clayey soils are poorly
drained and generally wetter and less disturbed than in the Panicum schinzii-
Salvia disertnes Sub-community. These areas are normally submerged during
the rainy season.. The trampling effect of livestock often results in exposed
areas.
This sub-community is characterized by the large hygrophytic grass,
Agrostis lachnantha, the thorny dwarf shrub, Protasparagus .suaveolens, and
the forb, Hibiscus trionum (species group B). Themeda triandra (species
group W) has a markedly lower cover-abundance, probably because of the
wetter habitat conditions.
An average number of ten species was recorded per sample plot (Table
8.1 ).
2 Protasparagus laricinus-Felicia filifolia Community
This plant community is associated with the crests of the undulating karroid
veld and calcareous-sandy deposits adjacent to lower-lying drainage
channels where the soil is clayey. Exposed sandstone rocks are common.
The dwarf shrub, Felicia filifolia, and the shrub, Protasparagus laricinus
(species group D), act as differentiating species (Table 8.1). The grasses
Aristida congesta, A. diffusa and Themeda triendrs (species group W) all
have a restricted dominance. The presence of the two Aristida species
indicates retrogression of the veld. Other grasses present, include Eragrostis
curvula (species group V) and Eragrostis lehmanniana (species group W,
Table 8.1). The thorny karroid shrub, Protasparagus striatus (species group
P), is the most important shrub.
214
An average of five species/relevé was recorded (Table 8.1).
3 Ch/oris virgata- Themeda triandra Community
The Ch/oris virgata- Themeda triandra Community is encountered on relative
poorly drained to well-drained, dry, lower-lying, calcareous and clayey soils
of the study area. These clayey soils are often covered with a thin layer of
wind-blown sand.
This community does not have exclusive diagnostic species, but it is
characterized by the strong and continuous presence of the small pioneer
grass, Ch/oris virgata (species group G). According to Van Oudtshoorn
(1991) C. virgata is a fast-growing, palatable grass which is adapted to
overgrazing and trampling. Themeda triandra (species ·group W) has a high
cover-abundance throughout the entire community. The only other
commonly occurring grasses, Eragrostis /ehmanniana and Aristida congesta,
have a low abundance value (species group W, Table 8.1).
Two sub-communities -are distinguishable in this plant community (Table
8.1 ).
3. 1 Xanthium spinosum-Senecio consanguineus Sub-community
This sub-community was encountered on the footslopes of hills where
clayey deposits occur. Fine gravel and stones, primarily of sandstone, but
also doJerite cover the moist soil surface.
The differentiating species of this sub-community, all with low cover-
abundances, are listed in species group E (Table 8.1). Ch/oris virgata
(species group G), Aristida congesta and Themeda triandra (species group
W) are the only constantly occurring graminoids (Table 8.1). The karroid
dwarf shrub, Pentzia g/obosa (species group W) is the noteworthy shrub
present. P. g/obosa is an encroacher species and is especially abundant in
the ecotone between dry grasslands and karroid areas (Anonymous 1968).
215
An average of ten species/relevé was recorded (Table 8.1.).
3.2 He/ichrysum dregeanum-Uroch/oa panicoides Sub-community
This sub-community was encountered on black turfish soil with sandy
deposits adjacent to drainage channels along public roads. No surface rock
or gravel occurs. The soil is poorly drained and patches of water are visible
for weeks after good rains.
He/ichrysum dregeanum and Uroch/oa panicoides, and to a lesser extent
Panicum maximum (species group.G), are the differentiating species present.
Only H. dregeanum is abundant. H. dregeanum, normally associated with
grasses is drought resistant, but does not normally grow during dry seasons
and droughts (Anonymous 1968). The pioneer grass, Ch/oris vlrqet«
(species group G), has an infrequent presence. The three grasses listed in
species group W, especially Themeda triandra and Aristida congesta, have
slightly higher cover-abundance values (Table 8.1).
An average of eight species/relevé was recorded (Table 8.1).
4 Herpochtoe fa/x-Elionurus muticus Community
As indicated by Werger & Coetzee (1978), this grassland coincides largely
with Acocks's (1988) Cymbopogon-Themeda Veld (Veld type 48), the
Highland Sourveld to Cymbopogon- Themeda veld transition (Veld type 56)
and the Southern Tall Grassveld (Veld type 65). Du Preez (1991) refers. in
. low & Rebelo ('996) to this grassland as Moist Cold Highveld Grassland.
This sour grassland is localized, occurring only on deep sandy and leached
soils of the sand stone terraces and plateaux in the south-eastern corner of
the study area, near Zastron. Exposed rocks, however, give the habitat a
rocky appearance. This area mainly falls within the 600-800 mm p.a. rainfall
interval where Avalon and Clovelly soils are the most abundant. In some
areas the vegetation is relatively undisturbed and utilization of grasses by
216
llvestock is restricted to the minimum. According to Roberts (1966), this
type of grassland is associated with cool, moist conditions that usually
occur at high altitudes. Similar communities were described by Du Preez
(1991), Eckhardt (1993) and Fuls (1993).
The diagnostics are listed in species group H (Table 8.1). The most
abundant grasses are Harpoeh/oa fa/x, Triehoneura grandig/umis, Braehiaria
serrata, Cymbopogon dieter/enii, Tristaehya /eueothrix and Eragrostis
eapensis. Other grasses present include Setaria sphaee/ata (species group I),
Elionurus mutieus (species group K), Heteropogon eontortus (species group
S), Digitaria eriantha, Eragrostis eurvu/a (species group V) and Themeda
triandra (species group W, Table 8.1).
A total of 37 species were recorded with an average of 29 species/relevé
(Table 8.1).
5 Eragrostis gummiflua- Themeda triandra Community
The Eragrostis gummiflua- Themeda triandra grassland is primarily associated
with moist habitats that vary from drainage channels with duplex soils to
higher-lying areas where rocky soils are common .. These areas also vary
from moderately disturbed to relatively undisturbed. The habitat conditions
are similar to that of the Eragrostis gummiflua-Cynodon daety/on Grassland
described by Coetzee (1993) in the Pretoria-Witbank-Heidelberg Area. Deep
Clovellyand Hutton soils (> 500 mm deep) with a clay content of 15%-
20% are prominent. Although inconspicuous here, Themeda triandra is
absent from the Eragrostis gummiflua-Cynodon daety/on Grassland (Coetzee
1993).
The presence of Eragrostis gummiflua differentiates this plant community
(species group L, Table 8.1). This species often has a high cover-abundance
and dominates the vegetation. According to Van Oudtshoorn (1991), E.
gummiflua usually occurs in high rainfall areas and is often abundant in
drainage channels. E. gummiflua prefers sandy and rocky soils and is
regarded as unpalatable to livestock. Trees and shrubs are absent and the
1.....-________________________________________ __ _!
217
whole vegetation unit occurs in full sun. Other graminoids present include
Setaria sphacelata (species group I), Sporobolus fimbriatus (species group
M), Cymbopogon plurinodis (species group 0), Digitaria eriantha (species
group V) and Themeda triandra (species group W, Table 8.1 ,.
Two distinct sub-communities are present (Table 8.1).
5. 1 Elionurus muticus- Triraphis andropogonoides Sub-community
This sub-community occurs on moderately drained to well-drained, trampled
rocky soil of the higher-lying areas.
The presence of the grasses Elionurus muticus and Triraphis
andropogonoides (species group K) as well as the absence of Sporobolus
fimbriatus (species group M) differentiate this sub-community from the
Eragrostis gummiflua-Sporobolus fimbriatus Sub-community (Table 8.1).
Eragrostis gummiflua (species group l) and Themeda triandra together aften
form dense stands (Table 8.1). Also noteworthy is the low presence of
species from species group W with T. triandra the only representative (Table
8.1 ).
An average of six species/relevé was recorded (Table 8.1).
5.2 Eragrostis gummiflua-Sporobolus fimbriatus SUb-community
The Eragrostis gummiflua:"Sporobolus fimbriatus Sub-community is primarily
associated with the more stable veld of the Eragrostis gummiflua- Themeda
triandra Community. The soils are clayey and covered by a layer of wind-
blown sand (duplex soils).
Conspicuous is the constant dominance of Eragrostis gummiflua (species
group lj. The presence of the large graminoid, Sporobotus fimbriatus-
(species group M);. further characterizes this plant community. Cymbopogon
plurinodis (species group 0), a large tufted graminoid, is widely distributed,
218
but has a low dominance value (Table 8.1). According to Van Oudtshoorn
(1991), Cymbopogon p/urinodis often grows in association with Themeda
triandra, but the latter only has a patchy occurrence in this sub-community
(Table 8.1). Setaria sphace/ata (species group I) is also present, but
inconspicuous (Table 8.1).
An average of seven species/relevé was recorded (Table 8.1).
6 Sporobo/us fimbriatus- Themeda triandra Community
This grassland is primarily associated with the higher-lying well-drained soils
in sandy to rocky parts of the undulating landscape. Generally the soil
structure varies from sandy to marginally clayey to rocky.
Sporobo/us fimbriatus (species group M), a highly palatable grass with a
high foliage production, acts as differentiating species (Table 8.1).
According to Van Oudtshoorn (1991) this grass has a wide distribution in
the Grassland Biome of South Africa and occupies a great variety of, often
moist, habitats. This community is principally differentiated from the
Eragrostis gummiflua- Themeda triandra Community by the total absence of
Eragrostis gummiflua (species group L).
Other grasses present are Panicum catoreturn (species group N),
Cymbopogon p/urinodis (species group 0), Eragrostis obtusa, E. curvu/a,
Digitaria eriantha (species group V), Aristida diffusa, Eragrostis /ehmanniana
and Themeda triandra (species group W, Table 8.1). Quite a number of
forbs were found in this community, but are inconspicuous.
Two distinct sub-communities further subdivide this community (Table
8.1 ).
219
6.1 Cymbopogon plurinodis-Eragrostis curvula Sub-community
This grassland was encountered on the crests of the higher parts of the
undulating terrain. The soils are rocky and well-drained.
The Cymbopogon plurinodis-Eragrostis curvula Sub-community is
characterized by the combined presence and mostly high abundance of
Themeda triandra (species group W), Sporobelus fimbriatus (species group
M) and Cymbopogon plurinodis (species group 0), as well as the restricted
occurrence of Panicum coloratum (species group N). No diagnostic species
occur. Digitaria eriantha (species group V) has a restricted dominance and
Eragrostis curvula (species group V) are the only other abundant grasses
present (Table 8.1). De Winter _(1955) regards E. curvula as the most
variable species in the genus, Eragrostis, in southern Africa. This species
occurs naturally only as far north as Kenya, but cultivars have been
introduced as pasture grasses throughout the tropics. It often occurs in
disturbed situations as a pioneer species (Gibbs RusseIl & Spies 1988). The
constant presence of Chrysocoma ciliata and Pentzia globosa (species
group W) indicates Karoo-encroachment.
An average of seven species/relevé was encountered (Table 8.1).
6.2 Sporobotus fimbriatus-Eragrostis lehmanniana Sub-community
A type of grassland encountered on well-drained sandy deposits. The soil is
rocky with eroding sandstone covering it. Cymbopogon plurinodis, normally
a common site on rocky soil, is absent from this sub-community. A stronger
presence of Eragrostis lehmanniana (species group W) further differentiates
this sub-community. Themeda triandra (species group W) only has a patchy
occurrence and is mostly non-conspicuous (Table 8.1). The presence of
Eragrostis obtusa (species group V) is indicative of overgrazed pasture (Van
Oudtshoorn 1991).
An average of five species/relevé was recorded for this sub-community
(Table 8.1).
220
7 Cymbopogon plurinodis- Themeda triandra Community
The Cymbopogon plurinodis- Themeda triandra Community is associated with
the moderately utilized to moderately under utilized, moist, rocky slopes of
hills. The soils are mostly of doleritic origin, but patches of sandstone and
clayey soil also occur. Big dolerite boulders on the slopes are a common
sight. The Eragrostis curvula- Themeda triandra Grassland, described by Fuls
et al. (1992 b) basically has the same habitat conditions than were
encountered here.
Exclusive diagnostic species are absent, being rather characterized by the
conspicuous dominance of Themeda triandra (species group W) and
constant presence of Cymbopogon plurinodis (species group 0, Table 8.1).
This community is represented by 23 species of which only a few occur
widespread. The presence of Pentzie globosa (species group W) especially in
the low-lying areas is a sure sign of Karoo invasion and grassland
degradation (Anonymous 1968).
Two distinct sub-communities further characterize this community (Table
8.1).
7. 1 Panicum cotorstum- Themeda triandra Sub-community
This grassland community is associated with the moist areas of east-facing
hillslopes. The habitat is less rocky than that of the Themeda triandra-
Aristida diffusa Sub-community. The soils are deep (> 200 mm) and clayey
(> 40% clay in the B-horizon). Dolerite stones and rocks (> 0.5 m in
diameter) are visible on the soil surface.
The presence of Panicum coloratum (species group N) differentiates this
sub-community from the Themeda triandra-Aristida diffusa Sub-community.
The dominance of Themeda triandra (species group W) is exceptional. The
highly unpalatable grass, Cymbopogon plurinodls (species group 0) I is also
widely distributed, but has a lower cover-abundance. Other grasses present
L-_____________________________________________________________________ _ _
221
are Digitaria eriantha, Eragrostis curvula and E. obtusa (species group V), all
having patchy occurrences (Table 8.1).
An average of five soectes/retevë was recorded for this sub-community
(Table 8.1).
7.2 Themeda triandra-Aristida diffusa Sub-community
This grassland is associated with the moderately utilized moist south- and
east-facing rocky slopes. The soil is shallow « 100 mm deep) and rocky.
Big dolerite boulders (> 1 m in diameter) are a common phenomenon.
The Themeda triandra-Aristida diffusa Sub-community is dominated by
the relatively large, tufted, perennial grass, Themeda triandra (species group
W). Besides the absence of Panicum coloratum (species group N) from this
sub-community, the patchy occurrence of Aristida diffusa further
differentiates these sub-communities (Table 8.1). Pentzia globosa (species
group W) was present in about half of the relevés and indicates pasture
degradation and Karoo encroachment.
8 Heteropogon contortos- Themeda triandra Community
This grassland occurs on westerly, easterly, northern and to a lesser extent
on southerly hillsides. The south-facing hill slopes characteristically are
associated with larger shrubs and trees. The distribution pattern of this
grassland apparently depends primarily on variations in irradiation. Variations
in moisture and micro-climate are related to differences in irradiation due to
different aspects and gradients (Fuls 1993). Heteropogon contortus-
Themeda triandra Communities were described by Bredenkamp et al. (1989)
in the Potchefstroom-Fochville-Parys area, Coetzee (1993) in the Pretoria-
Witbank':'Heidelberg area and Fuls et al. (1992 a) on the rocky outcrops of
the northern Free State. The habitat conditions described by Fuls et al.
(1992 a) under the Aristido canescentis- Themedatalia triandrae are similar to
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the conditions found here. The soils are generally shallow and rocky. Sandy
deposits occur in the lower-lying areas.
The north-facing slopes were, in general, found to be drier and often
severely overutilized by livestock. The Heteropogon contortus- Themeda
triandra Community thus occurs primarily in areas more utilized than the
Cymbopogon plurinodis- Themeda triandra Community. This confirms the
fact that C. plurinodis is a notably unpalatable species which tends to
increase in underutilized areas, being referred to as a souring process (Bosch
1989).
The most common, often co-dominant grasses encountered in this
grassland are the medium to large tufted perennials Heteropogon contortus
(species group S), Digitaria eriantha (species group V), Eragrostis
tetunenniene, Aristida congesta, A. diffusa and Themeda triandra (species
group W, Table 8.1). H. contortus is known from tropical and warm regions
throughout the world, where it is a common component of grassland and
savanna (Gibbs RusseIl & Spies 1988). Clayton & Renvoize (1986) report
that it is a most variable species, which previously has been subdivided into
intraspecific categories according to the hairiness of the pedicelled spikelets.
In South Africa, ChippindalI (1955) comments on the considerable variation
of H. contortus in habitat, size and hairiness. This species tends to dominate
in the eastern regions of South Africa and is especially abundant in
Gauteng, the Northern Province and Mpumalanga. Shrubs encountered were
Euclea crispa subsp. ovata, the thorny shrub Protasparagus striatus (species
group P) and Rhigozum obovatum (species group Q, Table 8.1).
Three distinct sub-communities are recognizable (Table 8.1).
8.1 Cymbopogon plurinodis-Heteropogon contortus Sub-community
This sub-community is associated with undisturbed, rocky, east-facing
slopes of hills. The stronger presence of Cymbopogon plunnodis (species
group 0) is indicative of a souring process, previously mentioned.
223
No exclusive diagnostic species occur and only a few species are
abundant (Table 8.1). The grasses Cymbopogon plurinodis (species group
0), Heteropogon contortus (species group S) and Themeda triandra (species
group W)· dominate this grassland. Also present, but inconspicuous, are
other grasses such as Eragrostis curvula, E. obtusa (species group Vl,
Aristida congesta and Eragrostis lehmanniana (species group W, Table 8.1).
An average of six species/relevé. was recorded for this sub-community
(Table 8.1).
8.2 Heteropogon contortus- Themeda triandra Sub-community
The Heteropogon contortus- Themeda triandra Sub-community occurs on the
north-facing midslopes and plateaux of hills where big dolerite boulders are
common. The soil is extremely shallow « 100 mm deep) and is often
covered by flat rock slabs. Isolated patches of this grassland were also
found on dry, disturbed west-facing slopes.
This grassland sub-community is primarily characterized by the absence
of diagnostic species and it also lacks Cymbopogon plurinodis which is
prominent in the Cymbopogon plurinodis-Heteropogon contortus Sub-
community (Table 8.1). Heteropogon contortus (species group S) and
Themeda triandra (species group W) are the only two abundant and
dominant grasses present (Table 8.1).
An average of five species/relevé was recorded for this sub-community
(Table 8.1).
8.3 Enneapogon scoparius-Hermannia vestita Sub-community
The distribution of this plant community is restricted to the southern and
south-western parts of the study area in the region of the Vanderkloof Dam.
The substratum is formed bv Ecca and Dwyka deposits and, in the
westernmost section of the Orange River, by Ventersdorp lavas. Only the
~-------------------------------------------------------------------
224
upper parts of the isolated hills consist of Beaufort deposits and dolerite.
Soils are usually lithosols or of a sandy loam type except in some localities
north of the river where extensive deposits of Kalahari sand have
accumulated (Werger 1980).
This sub-community is characterized by the species listed in species
group R (Table 8.1). Enneapogon scoparius and Cenchrus ciliaris (species
group R) are the differentiating grass species, while Stachys rugosa and
Hermannia vestlts are the differentiating forb species (Table 8.1). According
to Gibbs Russeil & Spies (1988), C. ciliaris is a common savanna species
which occurs throughout Africa to Arabia and India. According to them this
species has a wider distribution than the most other important pasture
grasses in South Africa. C. ciliaris is usually found in rocky places, which
may be its natural habitat in the cooler parts of its range, but there are
indications that in warmer parts it was of general occurrence and of great
importance (Acocks 1971). Heteropogon contortus (species group S, Table
8.1) is the dominant, but Themeda triendrs. (species group W) only has an
infrequent occurrence. Other grasses present, but less common, include
Digitaria eriantha (species group V) and Aristida diffusa (species group W,
Table 8.1).
Two variants were distinguished. (Table 8.1).
8.3.1 Protasparagus striatus-Euclea crispa subsp. ovata Variant
The Protasparagus striatus-Euclea crispa subsp. ovata Variant is primarily
associated with the upper slopes and crests of hills near the Vanderkloof
Dam. The habitat is rocky and the vegetation overgrazed.
This variant contains 15 species (Table 8.1). The small, thorny shrub,
Protesperequs striatus and Euclea crispa subsp. ovata (species group P) are
the differentiating species. The dominance of Heteropogon contortus
(species group S) and the scanty occurrence of Themeda triandra (species
group W), furthermore, characterize this vegetation unit (Table 8.1).
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8.3.2 Stachys rugosa-Eustachys paspaloides Variant
This variant is found along crests and plateaux of hills. Big boulders are a
common sight on the crests while flat rock slabs are more common on the
plateaux. The soil is shallow « 100 mm) and covered with eroded dolerite
stones.
The hardy, small, drought resistant fern, Cheilanthes eckloniana, and the
forb Stachys rugosa (species group R) grow very well in the crevices
between the rocks. Euclea crispa subsp. ovata and Protasparagus striatus
(species group P) are absent but the grasses Enneapogon scoparius,
Cenchrus ciliaris, (species group R), Heteropogon contortus (species group
S), Digitaria eriantha (species group V) and Aristida diffusa (species group
W) are important (Table 8.1). Also conspicuous is the absence of Themeda
triandra (Table 8.1).
9 Rhus cilia ta- Themeda triandra Community
The Rhus ciliata- Themeda triandra Community was encountered on the
footslopes of dolerite hills. Accord ing to Fuls (1993) the habitat of the
footslopes in the northern Free State was found to be markedly
homogeneous, which was also true of the present study. The soils of the
footslopes are mostly eroded and covered with sand, pieces of fine gravel
and stones.
The dwarf shrub, Rhus ciliata (species group T), differentiates this
community and is also sub-dominant after Themeda triandra (Table 8.1).
The Karoo-encroacher, Chrysocoma ciliata (species group W), is a typical
karroid shrublet and is considered to be an important element of Karoo
invasion in the Grassland Biome (Du Preez 1979). This unpalatable dwarf
shrub is associated with veld degradation and increases with heavy
overgrazing (Anonymous 1968). Sixteen species were listed in this
community.
226
Two sub-communities were recognized (Table 8.1).
9.1 Heteropogon contortus-Ctuvsocorne ciliata Sub-community
The distribution of this sub-community was found to be restricted to areas
where no rocks or stones are visible on the soil surface. Fine gravel,
however, is common.
Heteropogon contortus (species group S) differentiates it from the Rhus
ciliata-Chrysocoma ciliata Sub-community. Besides H. contortus,
Chrysocoma ciliata and Themeda triandra (species group W) are the only
other noteworthy species present (Table 8.1).
An average of five species/relevé was recorded (Table 8.1).
9.2 Rhus ciliata-Chrysocoma ciliata Sub-community
Besides gravel covering the soil surface and conspicuous big rocks present,
this sub-community was found under virtually the same habitat conditions
as the Heteropogon contortus-Chrysocoma einete Sub-community. The
grass Heteropogon contortus is absent and Themeda triendrs (species group
W) has a higher cover-abundance· (Table 8.1). Also present is a patchy
occurrence of Eragrostis lehmanniana (species group W).
An average of four species/relevé was recorded (Table 8.1).
10 Euryops empetrifolius-Eriocephalus spineseens Community
The Euryops empetrifolius-Eriocephalus spineseens Community is primarily
associated with the stony, dry upper east-facing slopes of hills where big
sandstone rocks virtually cover the soil. Continuous weathering of these
rocks gives the habitat a sandy appearance.
227
The diagnostic species are the karroid dwarf shrubs, Euryops
empetrifolius and the thorny Eriocephalus spineseens (species group S,
Table 8.1). The community is, furthermore, completely dominated by
Euryops empetrifolius (Table 8.1 l. This grassland is also characterized by
the presence of the grasses Digitaria eriantha (species group V), Eragrostis
lehmanniana, Aristida diffusa and Themeda triandra (species group W),
however only T. triandra .is abundant (Table 8.1 l.
An average of four species/relevé was recorded (Table 8.1).
11 Digitaria ertenttie- Themeda triandra Community
This grassland is predominantly associated with the slightly moist to dry,
slopes and plateaux of hills in the central parts of the study area. The
aspects were found to be exclusively westerly and easterly. Big dolerite
rocks are a common sight.
This plant community lacks diagnostic species and generally has a low
species diversity. The grasses Digitaria eriantha (species group V) and
Themeda triandra (species group VV), however, dominate the vegetation.
The regular occurrence of the Karoo-encroacher, Chrysocoma ciliata, and
the small grass Eragrostis obtusa (species group V) is a sure sign of veld
and pasture degradation. Other grasses also commonly present include
Eragrostis curvula (species group V) and Eragrostis lehmanniana (species
group W, Table 8.1).
An average of five species/relevé was recorded (Table 8.1).
12 Themeda triandra-Eragrostis lehmanniana Community
I
This community occurs on dry, moderately utilized to underutilized rocky I
plains and slopes of low to moderately high hills in the southern parts of the I
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study area, north-west of Zastron. The Clovelly soil form is the most
prominent.
The Themeda triandra-Eragrostis lehmanniana grassland has no
exclusively diagnostic species, being rather characterized by the high cover-
abundance of Themeda triandra (species group W, Table 8.1). According to
Van Oudtshoorn ('991) and Eckhardt (' 993) well-managed fields are
principally characterized by dense stands of T. triandra. Other grasses
present include Eragrostis lehmanniana and Aristida congesta (species group
W, Table 8.1). The total absence of Digitaria eriantha is a sign of pasture
degradation.
An average of four species/relevé was recorded (Table 8.1).
ORDINATION
The scatter diagram illustrates the distribution of the major syntaxa along
the first and second axes (Fi.gure 8.2). Although no distinct discontinuity
occurs, the syntaxa are restricted to specific spatial areas in the ordination
diagram. Along the first axis a gradient is illustrated which may be related to
moisture, altitude and habitat disturbance. Plant communities to the left of
the diagram are adapted to a much drier and more disturbed habitat than
those to the right. Also illustrated on axis 1 is a gradient of altitude. The
sour high altitude Harpochloa .falx-Elionurus muticus Grassland are to the
right and those communities associated with lower altitudes are to the left.
Axis two in the ordination diagram accommodates a soit structure gradient.
Plant communities found on clayey and calcareous soils are to the top of the
diagram. Communities associated with clayey-sandy (duplex) and rocky soils
are grouped to the middle and sandy soils to the bottom of the diagram
(Figure 8.2).
229
DISCUSSION
The southern Free State offers a wide variety of habitats and micro-climates
due to variation in environmental factors (Figure 8.2) and are therefore
ecologically interpretable. Inadequate soil moisture is considered the
overriding factor limiting dry matter production in the arid and semi-arid
grasslands of South Africa. Thus in these areas, efficiency of water use by
natural grazing plants is critically important in relation to the production
potential of the veld (Coetsee 1975). According to Snyman (1989), the
aboveground phytomass production is the determining factor of water use
efficiency of grasses. The water use efficiency of natural pasture can
increase by using the correct managing principles and by ensuring that the
vegetation composition is correct (Snyman 1989).
Acocks (1988) suggests that the boundary between Karoo shrublands
and grasslands lies east of about 24° latitude and north of about 33°
longitude. Widespread deterioration in all veld types over the last 500 years
is evident and the extent to which such damage can be repaired by
relatively simple methods, such as resting and rotational grazing, depends
on how far the deterioration has progressed (Acocks 1988).
The grasslands of the southern Free State can be broadly classified as
the Themeda triandra-Eragrostis lehmanniana Grassland. Themeda triandra,
especially associated with climax grasslands on the highveld (Van.
Oudtshoorn 1991), followed by Digitaria eriantha, Eragrostis curvula, E.
lehmanniana, E. obtusa and Sporobolus fimbriatus are the most prominent
sweet grasses present. Cymbopogon plurinodis has a turpentine smell (Van
Oudtshoorn 1991) and lsregarded as unpalatable in sweet grasslands and
represents a sub-climax to climax stage in grassland succession and where
rainfall is adequate will give way to woody communities. The sweet
grassland is more disturbed than the sour high altitude Harpochloa falx-
Elionurus muticus Grassland as indicated by the numerous karroid species
present. Sourveld is poorly utilized bv animals during winter due to
unpalatability and low feed value (Coetsee 1975).
230
Bezuidenhout (1993) identified five phytosociological classes in the
western Transvaal grasslands. The most important grasses encountered
include (in order of importance) Eragrostis curvula, Themeda triandra,
Aristida conoeste. Elionurus muticus, Cymbopogon plurinodis, Heteropogon
contortus, Cynodon dactylon, Aristida diffusa, Cymbopogon excavatus,
Setaria flabel/ata, Eragrostis superba, Eragrostis gummiflua, Triraphis
andropogonoides, Melinis repens, Pogonarthria squarrosa, Panicum
coloratum, Sporobolus atricanus, Eragrostis lehmanniana and Setaria
nigrirostris.
The rainfall of the western Transvaal grasslands is erratic and varies
between 450 mm p.a. in the west to 770 mm p.a. in the east. The relatively
heterogeneous geology is represented by the Witwatersrand and
Ventersdorp Supergroups and the Transvaal Sequence with isolated
occurrences of old Archaic granites and Karoo Sequence sediments. Soils in
this area are heterogeneous and vary from clayey, due to great variation in
parent rock material (Bezuidenhout 1993). Bezuidenhout (1993) considered
available soil moisture, topographical position in relation to altitude, soil
depth, drainage, percentage of stones or rocks on the soil surface and to a
lesser extent percentage clay content the main contributing abiotic factors
influencing the distribution of the of the vegetation.
Eckhardt (1993) described three major grassland communities in the
north-eastern Free State, namely the Aristida juncitormis-Themeda triandra-,
Eragrostis plana- Themeda triandra- and Monocymbium ceresitorme-
Tristachya leucothrix Grassland. The most important and conspicuous
species is Themeda triandra. Other important grasses include Andropogon
appendiculatus, Aristida juncitormis, Elionurus muticus, Eragrostis curvula,
E. plana, Harpochloa talx, Heteropogon contortus, Psspstum dilatatum,
Pennisetum sphacelatum and Tristachya leucothrix.
The area studied by Eckhardt (1993) in the north-eastern corner of the
Free State is situated in the summer rainfall zone with an average annual
rainfall of 750 mm. The Karoo Sequence occupies almost the total study
area. Two important groups which can be distinguished here, are the Ecca
and Beaufort Groups. The Beaufort Group covers more than 80% of the
231
study area (Eckhardt 1993). According to Eckhardt (1993) the combined
influence of soil form, soil depth, moisture regime, altitude, aspect and
topography is determining the occurrence of a certain community rather
than a single factor on its own. In the southern Free State, soil moisture,
habitat disturbance and altitude and soil type determine the distribution of
grassland communities (Figure 8.2). According to O' Connor (1985) limited
data illustrate that long-term rainfall variability, independent of grazing
regime, has an overriding effect on compositional trends of grasslands in the
savanna regions of southern Africa. Because of the influence of rainfall, the
influence of grazing varies from the semi-arid to the more mesic savannas.
O' Connor (1985), however, emphasized that different species respond in a
markedly different manner to the same treatment under the same set of
conditions. In the Karoo, however, it seems that the activities of man play a
more important role in the determination of vegetation changes (Roux &
Opperman 1982). Heavy grazing in the Karoo eliminates the palatable
components, sometimes leaving only five or six poorly acceptable species
(Stuart-Hili & Mentis 1982).
According to Fuls (1993) prominent grasses encountered throughout the
northern Free State include Eragrostis curvule, Themeda triandra,
Cymbopogon pturinodis, Setaria sphacelata, Digitaria eriantha, Hyparrhenia
hirta, Eragrostis plana, Cynodon dactylon, Aristida congesta, Microchloa
caffra, Heteropogon contortus and Elionurus muticus. T. triandra is by far
the most dominant grass.
The north-eastern Free State is situated in the 600-700 mm p.a. rainfall
zone of the semi-arid climatic climax grassland of the Grassland Biome of
southern Africa. Geologically the area is underlain by the Ecca and Beaufort
Groups of the Karoo Sequence with dolerite dykes and sills occurring
throughout the area (Fuls 1993). According to Fuls {1993}, the
phytosociology of the vegetation is primarily influenced by soil moisture
variations on a macro- and micro-scale, utilization by herbivores and terrain
morphology. Soil type has a lesser influence on the vegetation distribution
than soil depth, soil moisture and rockiness. This was also the case here as
can be seen in the ordination (Figure 8.2).
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232
Grasslands are generally considered as the most important vegetation
units for livestock farming. Invasion of karroid species is evident throughout
the entire southern Free State. Chrysocoma ciliata and Pentzia globosa are
good examples (See Chapter 7). It is therefore necessary to manage them
according to ecotoqlcar principles to maintain optimum floristic composition
and subsequently achieve a high production per unit area (Eckhardt 1993).
According to Grunow (1973) the establishment of pastures on arable lands,
particularly on small farms and where veld is degraded, raises the
production potential of the farm. The practice of grazing summer-rested veld
continuously during the whole winter period and even during early summer
cannot be recommended as it can cause severe damage to certain species,
such as Themeda triandra and Eragrostis curvula (Coetsee 1975). On low
rainfall sweetveld it enables the veld to be adequately rested during the
rainy season. According to 0' Connor (1985) stocking rate, rather than
the system of grazing" has a far greater influence on compositional trends
of grasslands in the savanna regions of southern Africa.
In spite of all this, natural grasslands are being increasingly disturbed or
purposefully altered by man-made processes. Many of these lead to a
degradation of the natural vegetation, and for this reason there is an urgent
need for more effective management of our natural resources. The
presented delineation of the grassland communities and associated habitats
should be used as a basis for future management and conservation of these
areas.
233
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MCNAUGHTON, S.J. 1985. Ecology of a grazing ecosystem: The Serengeti.
Ecological monographs 55 (3): 259-294.
MENTIS, M.T. & HUNTLEY, B.J. 1982. A description of the Grassland
Biome Project. S. Afr. Nat. Sci. Prog. 62: 1-29.
MUELLER-DOMBOIS, D. & ELLENBERG, H. 1974. Aims and Methods of
Vegetation Ecology. WHey, New York.
0, CONNOR, T.G. 1985. A synthesis of field experiments concerning the
grass layer in the savanna regions of southern Africa. SCi. Prog. Rep.
No. 114. CSIR, Pretoria.
237
ROBERTS, B.A. 1966. The ecology of Thaba 'Nchu. A statistical study of
vegetation/habitat relationships. Unpublished Ph.D. (Agric.) dissertation.
University of Natal. Pietermaritzburg.
ROUX, P.W. & OPPERMAN, D.P.J. 1982. Gronderosie in die Karoobioom.
Co-operative Scientific Programmes, CSIR, Pretoria.
RUTHERFORD,M.C. & WESTFALL, A.H. 1994. Biomes of southern Africa -
an objective categorization. 2 nd edn. Mem. bot. Surv. S. Afr. 63: 1-
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SCHEEPERS,J.C. 1975. The plant ecology of the Kroonstad and Bethlehem
areas of the Highveld agricultural region.D.Sc. thesis, University of
Pretoria, Pretoria.
SCHEEPERS, J.C., 1986. Grassland Biome Project: Proceedings of the
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SNYMAN, H.A. 1989. Evapotranspiration and water use efficiency of
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S. Afr. 6 (3): 146-151.
STUART-HILL, G.C. & MENTIS, M.T. 1982. Coevolution of African grasses
and large herbivores. Proc. Grassi. Soc. Sth. Afr. 17: 122-128.
VAN OUDTSHOORN, F.P. 1991. Gids tot grasse van Suid-Afrika. Briza
Publications, Arcadia, Pretoria.
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238
WERGER, M.J.A. 1980. Phytosociology of the Upper Orange River Valley,
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239
CHAPTER 9
Vegetation ecology of the southern Free State
Phytosociology of the southern Free State: Riparian and Streambed
Vegetation
240
CHAPTER 9
PHYTOSOCIOlOGY OF THE SOUTHERN FREE STATE: RIPARIAN AND
STREAMBED VEGETATION
9. 1 INTRODUCTION
Begg (1986) defined a wetland as an area where excess of water is the
dominating factor determining the nature of soil development and types of
plant and animal communities living at the soil interface. Wetlands are
therefore water-dominated areas with impeded drainage where soils are
saturated with water (at least periodically) and where there is a
characteristic flora and fauna (Coetzee 1993). The Ramsar Convention
(Convention on Wetlands of International Importance especially as
Waterfowl Habitat) was adopted in February 1971 by the International
Conference on the Conservation of Wetlands and Waterfowl at the town of
Ramsar in Iran. Article 1.1 of this Convention defines wetlands as follows:
"areas of marsh, fen, peatland or water, whether natural or artificial,
permanent or temporary, with water that is static or flowing, fresh, brackish
or salt, including areas ot" marine water the depth of which at low tide does
not exceed six metres".
The World Conservation Strategy identified wetlands as one of the most
important life support system on this planet (Cowan 1991). Like many
countries of the world, South Africa is rapidly approaching the position of
maximum exploitation of its conventional water resources (Alexander 1985,
Walmsley 1988). South Africa is categorized as an arid country with 65% of
the land-surface area receiving a mean annual preCipitation of less than 500
mm (Cowan 1991). In South Africa, a country with very few wetlands, it
has been estimated that over half of the wetlands have been destroyed and
lost (Breen & Begg 1989). Wetlands are therefore a scarce commodity in
S'outh Africa and the remaining wetlands should be high on the list of areas
to be conserved.
241
Although South Africa is involved in the Ramsar Convention for some
time now (Cowan 1991), many wetlands are still being destroyed beyond
rehabilitation, making them one of South Africa's most endangered
ecosystem types (Walmsley 1988). The widespread ploughing of arable land
concomitant with livestock grazing pressure resulted in the destruction of
large portions of pristine vegetation in the southern Free State. The
sensitivity of hydrophilic vegetation makes the watercourses especially
vulnerable to degradation. In many cases the trampling effect at these sites
is so serious that most of the riverbank vegetation is completely destroyed
by erosion.
From a phytosociological viewpoint, very little is known about the
wetland vegetation in the southern Free State. As yet no research has been
done on the vegetation composition and condition of the wetland habitats of
the southern Free State to determine the state of health of these habitats.
To facilitate optimal resource utilization in general, a detailed survey of the
region has been undertaken. This survey forms an integral part of the
ultimate goal to compile a comprehensive synecological synthesis of the
Grassland Biome of South Africa (Scheepers 1986).
9.2 STUDY AREA
The present study includes the southern Free State and is situated to the
south of the 29° 00' S latitude and to the west of the 27° 00' E longitude,
encompassing approximately 27000 km2. Towns situated in the study area
are Bloemfontein, Bethulie, Luckhoff, Petrusburg, Fauresmith, Wepener and
Zastron (Figure 9.1). Figure 9.1 also portrays the rivers and dams in the
southern Free State; The names of important dams changed during 1994.
To be in line with Figure 9.1, the Hendrik Verwoerd Dam should read Gariep
Dam and the P.K. le Roux Dam, the Van der Kloof Dam.
Wetlands in the southern Free State are mostly riparian wetlands along
rivers and streams. Floodplains and vleis are mainly found in bottomland
situations (Van Zyl 1966). Permanently waterlogged soils are scarce and
seasonally standing water is mostly restricted to slow-draining watercourses
..._ .__I
242
of flat terrain. Slow-draining streams are common owing to the flatness of
the terrain in most of the study area (Land Type Survey Staff, in press).
According to Strahler (1975), climate plays an important role in the land-
and soil forming processes and also has a major influence on the distribution
of vegetation (Acocks 1988).
Schulze & McGee (1978) and Woodward & Williams (1987) allege that
precipitation and temperature are the most significant climatic factors in
vegetation development.
The entire study area is subjected to a summer rainfall climate, although
there are significant differences along the east-west gradient. The rainfall is
erratic, especially in the western part of the study area (300-400 mm/al and
increases along a gradient eastwards to 700 mm/a. This is caused by the
increasing relief from west to east and a decrease of average daily
temperatures from west to east (Van der Wall 1976, Schultze & McGee
1978). According to Eloff (1984) the depth of the A-horizons of soils
increase from west to east.
The main drainage basin of the study area is the Orange River. Other
smaller rivers include the Caledon, Riet and Madder Rivers.
Topography has a definite influence on the temperature of the study
area, especially along rivers (Barker 1985). The hottest months of the year
are from December to February with July the coldest month of the year.
A more detailed description at' the physical environment and climate is
given elsewhere (Chapter 2).
9.3 METHODS
Relevés were compiled in 70 stratified random sample plots. Stratification
was based on terrain morphology (riverbanks, streambanks, bottomlands
such as vleis), and land types. Pan vegetation of the dry south-western Free
243
State is discussed in Chapter 10 of this dissertation. Care was taken to
place sample plots on all the different terrain morphological units. Plot sizes
were fixed at 100 m2 (Scheepers 1975, Bredenkamp 1982, Eckhardt et al.
1993, Fuls 1993). In each sample plot a list of all species present was made
and the cover-abundance of each species noted using the Braun-Blanquet
scale (Mueller-Dombois & ElJenberg 1974).
Two-way indicator species analysis (lWINSPAN) (Hill 1979 b) was
applied to the floristic data set in order to derive a first approximation of the
vegetation types of the area. Refinement was done by means of Braun-
Blanquet procedures (Bredenkamp et al. 1989). The floristic data set was
further subjected to an ordination algorithm, Detrended Correspondence
Analysis (DECORANA) (Hill 1979. a), to determine vegetation gradients and
the relationship with environmental variables. Plant names conform to those
of Arnold & De Wet (1993). Other relevant information such as habitat
disturbance, degradation of vegetation, rockiness of the soil surface and
human impact on the habitat were also noted.
Herbarium specimens collected during this survey are housed at the Geo
Potts Herbarium (BFlU), Department of Botany and Genetics, UOFS,
Bloemfontein.
AU relevant soil information was collected from the land Type Survey
Staff (In Press), Soil Classification Working Group (1991) and Eloff (1984).
9.4 RESULTS AND DISCUSSION
The watercourses and adjacent areas of the southern Free State were often
found, to be disturbed and the vegetation overutilized and trampled by
livestock. These areas generally do not have a high species diversity and are
dominated by only a few forb species (Table 9.1). The wetland habitat of
the study area can be broadly classified as the Asclepias fruticosa-Cirsium
vulgare Wetland. Asclepias fruticosa and Cirsium vulgare (species group Y)
are generally found in the wetlands in the southern Free State. Only a few
dominant species occur and are' mainly associated with seasonally flooded
244
areas of the flat undulating plains including streams and riverbanks. The
hierarchical classification of the Wetland vegetation type is as follows:
1 Cvperos /ongus-Cyperus marginatus Riparian Vegetation
1.1 Cyperus /ongus-Agrostis /achnantha Stream bed Vegetation
1.2 Cyperus rupestris-Mariscus congestus Sub-community
1.3 Cyperus /ongus-Cynodon incomp/etus Sub-community
1.4 Cyperus /ongus-Portu/aca -oterecee Riparian Vegetation
1.4.1 Cyperus /ongus-Medicago /aciniata Riparian Vegetation
1.4.2 Cvperos /ongus-Persicaria serru/ata Riparian Vegetation
1.5 Fuirena hirsuta-Wah/enbergia androsacea Riparian Vegetation
1.5.1 Cvperas marginatus-Fuirena hirsuta Riparian Vegetation
1.5.2 Sporobo/us fimbriatus-Cirsium vu/gare Riparian Vegetation
1.6 Sporobo/us toeledos-Setmus dioicus Riparian Vegetation
1.7 Chenopodium criststum-Cvperus marginatus Riparian Vegetation
2 Scirous nodosus Riparian and Streambeds Vegetation
2.1 Scirpus nodosus-Cyperus longus Streambed Vegetation
2.2 Scirous nodosus-Cyperus /aevigatus Streambed Vegetation
2.3 Juncus kraussii-Chrysocoma ciliata Stream bed Vegetation
2.4 Scirpus nodosus-Juncus kreussii Riparian Vegetation
2.5 Scirpus nodosus-Cirsium vu/gare Riparian Vegetation
3 Typha cepensis-Senecio consanguineus Streambed Vegetation
3.1 Juncus exsertus-Helichrysum turgudulum Riparian Vegetation
3.2 Rumex /anceo/atus-Juncus rigidus Streambed Vegetation
4 Phragmites australis-Protasparagus laricinus Streambed Vegetation
5 Protasparagus /aricinus-Phy/a nodiflora Riparian Vegetation
6 Salix babylonica-Lactuca dregeana Streambed Vegetation
7 Miscanthus cepensts- Typha cepensis Riverbank Vegetation
8 Agrostis lachnantha Wetlands of the drainage channels
245
8.1 Pennisetum sphacelatum-Miscanthus capensis Wet drainage channels
8.2 Cyperus eragrostis-Paspa/um di/atatum Drainage channels
DESCRIPTION OF THE COMMUNITIES
1 Cyperus longus-Cyperus marginatus Riparian Vegetation
The Cyperus longus-Cyperus marginatus Riparian Vegetation' is strongly
associated with poorly drained, moderately deep, clayey (> 25% clay
content - A - & B-horizons) soils with alluvium often occurring. Less than
10% of the soil surface is covered by stones or rocks. This plant community
is encountered on flat bottomlands and floodplains along rivers and streams.
The hygrophytes, Cyperus longus and C. marginatus (species group I),
characterize this wetland type (Table 9.1). These species were often
encountered growing in or adjacent to watercourses. Other frequently
occurring species include Asclepias fruticosa and Cirsium vulgare (species
group X, Table 9.1).
Seven distinct sub-communities further divide this wetland (Table 9.1)
1.1 Cyperus longus-Agrostis lachnantha Streambed Vegetation
This streambed sub-community is either growing in water or adjacent to
open or flowing water. The riverbanks consist partly of rocks and gravel and
are generally characterized by the Dundee soil form, consisting of stratified
alluvium. The relatively low clay content in the upper layers in some areas
can be ascribed to the flowing of gravel and sand particles from upstream.
This streambed has no exclusive diagnostic species group and is
represented by only a few species with the sedges, Cyperus longus and C.
marginatus (species group I) and the grass, Agrostis lachnantha (species
group X), the most abundant (Table 9. 1).
246
1.2 Cyperus rupestris-Mariscus congestus Sub-community
A sub-community occurring on the banks of perennial rivers and streams
which are occasionally in flood. No rocks and gravel are visible on the
clayey (> 35% clay) soil surface. A layer of river sand covers the soil
surface. Little habitat disturbance occurs although patches of overgrazing
can be encountered.
This sub-community is characterized by the species listed in species
group A (Table 9.1). The differentiating species are the hygrophytes
Cyperus rupestris and Mariscus congestus and the widespread couch grass
Cynodon tncompletus. Of note is the restricted dominance of Cyperus
longus (species group I) and the frequent occurrence of Asclepias fruticosa
(species group Yl. A. fruticosa, commonly known as "miikweed" is virtually
restricted to sandy deposits (Anonymous 1968), It is unpalatable, but is
regularly eaten by Insects and worms (Anonymous 1968). Trees and shrubs
are infrequent, but the presence of Protasparagus laricinus (species group R)
and Diospyros Iycioides (species group S) further differentiates this wetland
from the Cyperus longus-Agrostis lachnantha Streambeds. Cirsium vu/gare
(species group Y) was locally totally dominant (Table 9.1).
1.3 Cyperus longus-Cynodon incompletus Sub-community
This infrequent wetland is restricted to the relatively dry undulating
landscape and drainage channels. Fine gravel cover 10-40% of the surface.
Species of species groups A and B characterize this sub-community and
are indicative of habitat degradation (Table 9.1), The absence of Cyperus
rupestris, Mariscus congestus (species group A), as well as Asclepias
fruticosa (species group Y), differentiate this sub-community from the
Cyperus rupestris-Mertscus congestus Riparian Sub-community (Table 9.1).
Cyperus longus (species group I) is less conspicuous and the only other
noteworthy species present (Table 9.1).
~-----------------------------------------------------------
247
1.4 Cyperus longus-Portulaca oleracea Riparian Vegetation
This riparian sub-community is encountered on flat bottomlands or
flood plains along the beds of seasonally flowing rivers and streams. The
soils are deep (> 500 mm) and clayey (> 35%). The trampling effect of
livestock often results in denuded areas along the watercourses.
The sedge, Cyperus longus (species group I), dominates the vegetation
with Portulaca oleracea (species group D)·also conspicuous. The latter is a
pioneer and grows equally well in full sun as in the shade.
Two distinct variants further differentiate this wetland (Table 9.1).
1.4.1 Cyperus longus-Medicago laciniata Riparian Vegetation
This vegetation unit is restricted to the flood plains of seasonally flowing
rivers. The soil is clayey and its surface covered with a layer of river sand
(> 100 mm thick) (duplex soils).
The reeds Medicago laciniata, Xanthium strumarium and Atriplex
semibaccata (species group C) differentiate the vegetation with Portulaca
oleracea (species group D) also prominent. The variant is. dominated by
Cyperus longus (species group I, Table 9.1). Other prominent species are
scarce. The sprawling grass, Cynodon incompletus (species group A),
grows particularly well in the mud in the shade of Cyperus longus.
1.4.2 Cyperus longus-Persicaria serrutete Riparian Vegetation
The Cyperus longus-Persicaria serrulata Riparian Vegetation occurs along
the beds of rivers with shallow clayey « 100 mm deep) soil. No sandy
deposits overly the clay surface, but a layer of fine gravel (often > 100 mm
thick) occurs. Habitat disturbance due to human impact is noticeable.
Littering, especially, is common.
248
Species of species groups 0, I and Y occur with Cyperus longus (species
group I) the only conspicuous species (Table 9.1). The absence of species
from species groups A, Band C differentiates this variant from the Cvperus
longus-Medicago laciniata riparian vegetation (Table 9.1).
1.5 Fuirena hirsuta-Wahlenbergia androsacea Riparian Vegetation
Certain species of this sub-community are either growing in water or occur
directly adjacent to open or flowing water. These seasonal watercourses are
generally flowing during the rainy season. Habitat disturbance frequently
occurs and trampling by livestock often results in denuded areas. The soil is
clayey with big rocks (> 0.5 m in diameter) exposed on the soil surface.
Species of species group E are diagnostic of this sub-community with the
sedge Fuirena hirsuta the most prominent. Cyperus marginatus (species
group I) and Cirsium vulgare (species group Y) are also conspicuous,
especially on riverbeds._Other species present, but less-conspicuous, include
WahJenbergia androsacea, Ranunculus multifidus (species group E), Lobelia
thermalis and Juncus kraussii (species group M). The presence of J. kraussii
indicates brackish conditions.
Two distinct variants further divide this wetland (Table 9.1).
1.5.1 Cyperus marginatus-Fuirena hirsuta Riparian Vegetation
The Cyperus merqinetus-Fuirene hirsuta Riparian Vegetation occurs adjacent
to slow-flowing water bodies such as dams and seasonally waterlogged
streams. The soil is clayey and the surface trampled by cattle and sheep.
Exposed rocks cover 20-40 % of the soil surface.
This variant lacks exclusive diagnostic species, but the vegetation is
rather characterized by the strong presence of Fuirena hirsuta (species
group E) and Cyperus marginatus (species qroupl. Table 9.1).
249
1.5.2 Sporobolus fimbriatus-Citsium vulgare Riparian Vegetation
The vegetation associated with this variant of the Fuirena hirsuta-
Wah/enbergia androsacea Riparian Vegetation is trampled by cattle. No
rocks are visible on the soil surface.
This variant also lacks exclusive diagnostic species and is differentiated
from the Cyperus marginatus-Fuirena hirsuta Variant by the presence of the
species from species group H and the dominance of Cirsium vulgare (species
group Y). Other species present, most of which are inconspicuous, include
Fuirena hirsuta, Ranunculus multifidus (species group E), Sporobolus
virginicus and S. fimbriatus (species group H, Table 9.1).
1.6 Sporobolus ioclados-Scirpus dioicus Riparian Vegetation
Th~s infrequent vegetation group occurs on trampled soil, but to a lesser
extent than the Fuirena hirsuta- Wahlenbergia androsacea Riparian
Vegetation. No rocks occur on the surface. Fine gravel, almost as fine as
river sand, cover the soil surface.
Diagnostic species are those listed in species group F (Table 9.1).
According to Van Oudtshoorn (1991), Sporobolus ioc/ados generally grows
well in brackish soil. Scirpus .dtotcus (species group F) is the only other
diagnostic species present, but the restricted dominance of Juncus kraussii
(species group M) is more noteworthy and further indicates brackish habitat
(Table 9.1).
1.7 Chenopodium cristratum-Cyperus marginatus Riparian Vegetation
The habitat of this infrequent sub-community is not clearly distinguishable
from the previous two wetlands. Habitat disturbance also occurs, but to a
lesser extent. littering, especially with plastic bags and bottles are a
250
common phenomenon. Alluvium and gravel occur on the surface and the
soil appears to be more calcareous in nature. Footprints of cattle are
conspicuous in the mud.
Chenopodium cristatum (species group G), rather inconspicuous, is
diagnostic of this vegetation unit (Table 9.1). Other species which
frequently occur, include Sporobolus virginicus, S. fimbriatus (species group
H), Cyperus longus (species group I), Scirpus nodosus (species group L),
Lobelia thermalis (species group M) and Cirsium vulgare (species group Y).
S. fimbriatus and C. longus are often conspicuously dominant (Table 9.1).
2 Scirpus nodosus-Cirsium vulgare Riparian and Streambed Vegetation
This community occurs on the periodically dry streambeds and on edges of
pans. The riverbanks consist mainly of calcareous soil and is often clayey,
especially in the lower-lying areas which receive more moisture. Big rocks
are absent, but gravel gives these sites a stony appearance. The pans are
without any rocks. The zone of vegetation on the edges of pans is clearly
recognizable and can easily be distinguished by its structural appearance
from the vegetation found deeper in the pans. The erect vegetation is in
direct contrast to the creeping, carpet-like appearance of the vegetation in
the central areas of pans where the rhizomatous swamp grass, Diplachne
fusca, frequently occurs. Pan vegetation is discussed in Chapter 10 of this
dissertation.
Species of species groups I, J, K, L, M and Y characterize this vegetation
unit with Scirpus nodosus (species group L, Table 9.1) the differentiating
species. Also conspicuous are the scanty occurrence of species of species
groups A-H and N-V (Table 9.1).
Five distinct sub-communities divide this plant community (Table 9.1).
2.1 Scirous nodosus-Cyperus longus Streambed Vegetation
251
This sub-community is associated with less disturbed drier streambeds with
water patches occurring in the low-lying areas. The soil is clayey and no
rocks are visible on the surface.
The Scirpus nodosus-Cyperus longus Streambed Vegetation lacks
diagnostic species but is rather characterized by the restricted dominance of
Cyperus longus (species group I) and Scirpus nodosus (species group L,
Table 9.1). This streambed community is not particularly rich in species with
Juncus kraussii (species group M), Miscanthus capensis (species group V)
and Asclepias fruticosa (species group Y) the only other conspicuous
species (Table 9.1).
2.2 Scirpus nodosus-Cyperus laevigatus Stream bed Vegetation
The Scirpus nodosus-Cyperus laevigatus Streambed Végetation is associated
with less moist watercourses and often more sandy streambeds in
comparison to the Scirous nodosus-Cyperus Ionaus Sub-community. This
vegetation unit lacks clear diagnostic species. Only the sedge Cyperus
laevigatus (species group J) occurs as such. Cirsium vulgare (species group
Y) is the only conspicuous species and completely dominates the vegetation
(Table 9.1). C. vulgare stands are often very dense. Other abundant species
include Scirous nodosus (species group L), Lobelia thermalis (species group
M) and the swamp grass Agrostis lachnantha (species group X).
2.3 Juncus kraussii-Chrysocoma ciliata Streambed Vegetation
The Juncus kraussii-Chrysocoma cttiete Streambed Vegetation is associated
with slow-flowing perennial or seasonally perennial streams and vleis with
shallow streambed-incision. The calcareous-sandy soil of these streambeds
is moist and fine gravel occurs on the surface. This vegetation is heavily
overgrazed and the soil surface trampled.
The Karoo-encroacher, Cbrvsocome ciliata (species group K), is the sole
diagnostic species (Table· 9.1). Scirpus nodosus (species group L) and
252
Juncus kraussii (species group M) have restricted dominances and Asclepias
fruticosa (species group Yl also occurs, especially in the less sandy places
(Table 9.1 ,.
2.4 Scirpus nodosus-Juncus kreussii Riparian Vegetation
The Scirous nodosus-Juncus kraussii Riparian Vegetation is restricted to
higher-lying areas adjacent to pans. The soil is clayey and no rocks are
visible on the surface.
Only a few species occur and none of these is diagnostic. Scirpus
nodosus {species group L} and Juncus kraussii (species group M) are
dominant in places, with Lobelia thermalis (species group Ml, Protasparagus
laricinus (species,group R), Miscanthus espensis (species group V), Agrostis
lachnantha (species group X) also partly prominent (Table 9.1) .:
2.5 Scirpus nodosus-Cirsium vulgare Riparian Vegetation
This riparian vegetation is a transitional sub-community encountered on the
peripheral zone of pans and is not to be confused with the vegetation found
deeper in these pans. The soil is of a clayey nature with water patches in
the low-lying areas. This sub-community is similar to the Senecio
inaequidens-Cynodon transvaalensis Pan Community described by Eckhardt
et al. (1993) in the Vrede-Memel-Warden Area in the north-eastern Free
State .
.No diagnostic species occur and the vegetation is dominated by Scirpus
nodosus (species group Ll and Cirsium vulgare (species group Y). The
ve.getation, especially where C. vulgare dominates, is often very dense.
Other species are scarce, only Portu/aca oleracea (species group Dl and
Juncus kraussii (species group M) being present (Table 9.1).
3 Typha capensis-Senecio consanguineus Streambed Vegetation
~--------------------------------------------------------------------- -
253
The Typha capensis-Senecio consanguineus Streambed Vegetation is
associated with shallow streambeds where a mixture of clayey and clayey-
sandy soil occurs. Habitat disturbance due to trampling of livestock is a
common phenomenon.
The butlrush, Typha capensis, forming often very dense, homogeneous
stands and the forb Senecio consanguineus (species group P) are the only
differentiating species (Table 9.1).
Two distinct sub-communities characterize this plant community (Table
9.1 ).
3.1 Juncus exsertus-Helictotrichon turgudulum Riparian Vegetation
This wetland is encountered on vlei-edges which are not permanently
waterlogged. The soil is of a clayey nature. The surface is rock-less. Habitat
disturbance from trampling_frequently occurs.
The diagnostic species of the Juncus exsertus-Helictotrichon turgudulum
Sub-community are those listed in species group N (Table 9.1). Juncus
exsertus are the most prominent and has a restricted dominance. Typha
cepensis (species group P), the sedge Mariscus congestus (species group
A) and the grasses Helictotrichon turgudulum (species group N) and
Agrostis lachnantha (species group X) are the most frequently occurring
species. The noxious weed Xanthium strumarium (species group C) and the
grass Hyparrhenia dregeana (species group N) grow especially well in deep
clayey soil.
3.2 Rumex lanceolatus-Juncus rigidus Streambed Vegetation
This streambed community is associated with slower draining, waterlogged
streambeds. Distinctiv-e pools are absent. Habitat disturbance does occur,
but to a much lesser extent than in the Juncos exsertus-Helictotrichon
254
turgudulum Riparian Vegetation. Sandy-clayey soil occurs in the middle of
these streambeds.
Rumex lanceolatus and Juncus rigidus (species group 0) are the only
two differentiating species. This sub-community lacks Mariscus congestus
(species group A) and those species of species group N differentiating the
Juncus exsertus-Helictotrichon turgudulum Riparian Vegetation (Table 9.1).
Typha capensis (species group P) has a exceptionally high cover-abundance
and the vegetation often is very dense. These sites are popular nest-building
sites for water birds. Phragmites austral is (species group a) and Asclepias
fruticosa (species group Y) were found to be co-dominant of this streambed
vegetation (Table 9.1).
4 Phragmites australis-Protasparagus tertemus Streambed Vegetation
The Phragmites australis-Protasparagus /aricinus Streambed Vegetation is
primarily associated with the banks of perennial rivers and streams.
Streamflow is generally slow, but may accelerate between pools. Rapids
frequently occur and play a further role in the faster movement of water.
This vegetation unit lacks exclusive diagnostic species, but is rather
differentiated by the dominance of the reed, Phragmites austra/is (species
group a). P. australis is the most widespread flowering plant on earth (Good
1974; Gibbs RusseIl et al. 1990). Salix mucronata and Phyla nodiflora
(species group a) further differentiate this community with Protasparagus
/aricinus (species group RL the exotic Sa/ix baby/onica, and Diospyros
/ycioides (species group S) the only other noteworthy species present (Table
9.1 ).
5 Protasparagus laricinus-Phy/a nodiflora Riparian Vegetation
A vegetation group associated with shallow streambed incision and moist to
wet streambanks. The subsoil of the streambanks are at least periodically
L-- _
255
waterlogged during the rainy season. The soil is clayey with sandy areas
also abundant.
Only three species, Protasparagus laricinus (species group R), Phyla
nodif/ora (species group a) and Cirsium vu/gare (species group Y), are
worth mentioning (Table 9.1). Species of species groups A, C, I, 0 and 5
are also present, but they are inconspicuous (Table 9.1). Cirsium vu/gare
(species group Y) is often dominant, especially in areas with sandy deposits.
6 Sa/ix baby/onica-Lactuca dregeana Streambed Vegetation
This, relatively undisturbed streambed vegetation type, is associated with
moist riverbanks. No standing water occurs and the soil is clayey « 20 %
clay) or sandy, especially in the lower-lying areas. The exotic woody species
Salix babylonica (species group S) completely dominates the vegetation,
with Diospyros Iycioides (species group S) the only other woody species
present. Other species present include the grass Cynodon incomp/etus
(species group A), the Karoo-encroacher Chrysocoma ciliata (species group
K), Lactuca dregeana, Artemisia afra (species group 5) and Cirsium vu/gare
(species group Yl, all occurring in the shade of big S. babyionica.
7 Miscanthus ceaensts- Typha capensis Riverbank Vegetation
The Miscanthus espensis- Typha espensis Riverbank Vegetation is associated
with duplex soils on riverbanks. The soils of the bottomlands are clayey and
covered with a layer of sand (duplex soils). These soils are generally non-
rocky « 10% rocks). Habitat disturbance frequently occurs and signs of
human impact (litter) are clearly visible.
Differentiating species are those listed in species group T, all of which
have a low cover-abundance, but Miscanthus capensis (species group V)
completely dominates the vegetation (Table 9.1).
256
8 Agrostis lachnantha Wetlands of the drainage channels
The habitat of the drainage channels occupied by this community is
periodically eroded and disturbed. The soils are predominantly clayey but
patches of calcareous soil do occur. Standing water is often visible,
virtually for weeks after good rains.
Agrostis lachnantha (species group X), one of the most widespread of all
grasses (Glbbs RusseIl et al. 1990), occurs frequently and differentiates this
wetland community. This community has a low species diversity with
species listed in species groups A-T (Table 9.1) just about absent. The only
exception is Artemisia afra (species group S) which regularly occurs.
Two distinct sub-communities further divide this wetland (Table 9.1).
8.1 Pennisetum sphacelatum-Miscanthus capensis Wet drainage channels
This wetland is associated with periodically waterlogged drainage channels,
where predominantly clayey soil prevails.
Pennisetum sphacelatum is the only diagnostic species and completely
dominates the vegetation (species group U, Table 9.1). Due to the
dominance of this grass, other forbs are scarce and only grasses such as
Miscanthus capensis (species group V) and Agrostis lachnantha (species
group X) occur, both having fairly high cover-abundance values.
8.2 Cyperus eragrostis-Paspa/um di/atatum Drainage channel community
The Cyperus eragrostis-Paspalum dilatatum Sub-community is associated
with drainage channels along public roads. The habitat is usually disturbed,
not waterlogged and the soil is of a calcareous nature.
The sedge, Cyperus eragrostis and the perennial, rhizomatous grass,
Paspa/um di/atatum (species group W), are the most dominant of the
257
diagnostic species (species group W, Table 9.1) with Asclepias fruticosa
also frequently occurring (species group Y, Table 9.1). Where Pennisetum
sphacelatum completely dominates the Pennisetum sphacelatum-Miscanthus
capensis Wetland, it is absent from this sub-community where C. eragrostis
dominates (Table 9.1).
ORDINATION
In the scatter diagram the distribution of the major syntaxa along the first
and second axes of the ordination is given (Figure 9.2). Along the first axis,
which presents a soil texture gradient, the plant communities associated
with rocky soil (> 10% rocks) are situated to the left of the diagram and
those communities associated with less rocky soil « 10% rocks) towards
the right. Also along the first axis is a gradient of habitat disturbance.
Relatively undisturbed plant communities are to the left of the diagram with
the more disturbed communities to the right. A habitat gradient illustrates
the distribution of the plant communities along the second axis of the
diagram. Plant communities to the top ot the diagram are primarily
associated with drainage channels while those to the middle and bottom of
the diagram are primarily associated with rivers and streambeds (Figure·
9.2).
9.5 DISCUSSION
All plant communities could be related to specific environmental conditions
(Figure 9.2) and are therefore ecologically interpretable. Soil moisture and
the type of grazing management applied in a certain area, play an important
role by determining the type of vegetation in a that area (Eckhardt et al.
1993). According to them, the low species diversity of the wetland plant
communities of the Vrede-Memel-Warden Area is mainly due to regular
flooding, droughts and grazing of livestock. This was also the case within
the wetlands of the southern Free State. According to Van der Walt (1992),
numerous water birds were spotted in the pans and vleis of the north-
L__ - -
258
eastern Free State. This was not the case here with most water birds
spotted in the open pan communities (Chapter 10).
The most important species associated with the wetlands of the southern
Free State are the grass Agrostis lachnantha, the sedges Cyperus longus, C.
marginatus and Juncus kraussii and the forbs Asclepias truticose, Cirsium
vulgare and Lobelia thermalis.
Wetlands are considered as sensitive areas (Eckhardt 1993) and require
special attention as far as their management is concerned. Sound ecological
principles seem to be the only way to manage these areas. This implies .i.olru:
.alia the delimitation of the different wetlands, implementation of ecologically
sound veld management proqrarnmes, including the partial withdrawal of
livestock and veld burning programmes, and the process of drainage being
halted (Eckhardt 1993). Over utilization of vegetation and especially the
accompanying habitat degradation of these areas should be minimized in
order to ensure that the vegetation have more time to recover.
Human growth and utilization of fresh water on a sustained exponential
basis are pre-eminent components of any analysis of inland water resources.
Man must be recognized for what he ls: an animal whose population growth
is in an exponential phase (Wetzei 1983). The unfortunate effect of
essentially uncontrolled growth is that consumption increases in response to
rising supply. Every increase in supply is met by a corresponding increase in
consumption, because in contemporary society, voluntary control over
consumption is ineffective (Wetzei 1983). Fresh waters are a finite resource
and if we are not able to manage it properly the consequences will be
disastrous.
This delineation of the wetland communities of the southern Free State
should be used as the basis for future conservation strategies of these
areas. Because of the sensitivity of these areas and the continuous
degradation of wetland habitats one should hope that future management
and conservation strategies should be given higher priority.
259
9.5 REFERENCES
ACOCKS, J.P.H. 1988. Veld types of South Africa. 3 rd edn. Mem. bot.
Surv. S. Afr. 57: 1-146.
ALEXANDER, W.J.R. 1985. Hydrology of low latitude Southern Hemisphere
landmasses. Hydrobiologia 125: 75-83.
ANONYMOUS, 1968. Ken die karoobossie. Landbouweekblad. National
Media ltd., Cape Town.
ARNOLD, T.H. & DEWET, B. C. 1993. Plants of southern Africa: names and
distribution. Mem. bot. Surv. S. Afr. 62: 1-825.
BARKER, C.H. 1985. 'n Geomorfologiese studie van die
Mooirivieropvanggebied. M.Sc. thesis, Potchefstroom University for
Christian Higher Education, Potchefstroom.
BEGG, G.W. 1986. The Wetlands of Natal. Part 1. An overview of extent,
role and present status. Natal Town and Regional Planning Report 68: 1-
5.
BREDENKAMP, G.J. 1982. 'n Plantekologiese studie van die Manyeleti-
Wildtuin. D.Sc. thesis, University of Pretoria, Pretoria.
aREDENKAMP, G.J., JOUBERT, A. F. & BEZUIDENHOUT, H. 1989. A
reconnaissance survey of the vegetation of the plains in the
Potchefstroom - Fochville - Parys area. S. Afr. J. Bot. 55: 199-206.
BREEN,C.M. & BEGG,G. W. 1989. Conservation status of southern African
wetlands. In: Biotic Diversity in southern Africa: Concepts and
Conservation, ed. B. J. Huntley. Oxford University Press, Cape Town.
COETZEE, J.P. 1993. Phytosociology of the Ba and Ib land types in the
Pretoria-Witbank-Heidelberg area. M.Sc. thesis. University of Pretoria,
Pretoria.
260
COWAN, G.I. 1991. Wetlands enjoy high priority for protection. S. Afr.
Wetl. 1: 4-7.
ECKHARDT, H.C. 1993. A synecological study of the vegetation of the
north-eastern Orange Free State. Unpublished M.Sc. thesis. University of
Pretoria, Pretoria.
ECKHARDT, H.C., VAN ROOYEN, N. & BREDENKAMP, G.J. 1993. Wetland
plant communities of the Vrede-Memel-Warden area, north-eastern
Orange Free State. Navors. nas. Mus. Bloemfontein. 9(8): 246-262.
ELOFF, J.F. 1984. Die grondhulpbronne van die Vrystaatstreek. Ph.D.
thesis, University of Stellenbosch.
FULS, E.R. 1993. Vegetation ecology of the northern Orange Free State.
Unpublished Ph.D. dissertation. University of Pretoria, Pretoria.
GlBBS RUSSELL, G.E., WATSON, L., KOEKEMOER, M., SMOOK, L.,
BARKER, N.P., ANDERSON, H.M. & DALLWITZ, M.J. 1990. Grasses of
southern Africa. Mem. bot Surv. S. Afr. 58: 1-437.
GOOD, R. 1974. Geography of the flowering plants. Longmans, London.
HILL, M.O. 1979 a. DECORANA - a FORTRAN program for detrended
correspondence analysis and reciprocal averaging. Department of
Ecology and Systematics, Cornell University, Ithaca, New York.
HILL, M.O. 1979 b. TWINSPAN - a FORTRAN program arranging
multivariate data in an ordered two-way table by classification of
individuals and attributes. Cornel! University, Ithaca, New York.
LAND TYPE SURVEY STAFF (IN PRESS). Land types of the maps 2924 -
Koffiefontein and 2926 - Bloemfontein. Mem. agric. nat. Resources S.
Afr. No. 14.
I
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261
MACVICAR, C.N., LOXTON, R.F., LAMBRECHTS, J.J.N., LE ROUX, J., DE
VILLIERS, J.M., VERSTER, E., MERRYWEATHER, F.R., VAN ROOYEN,
T.H. & HARMSE, H.J. VON M. 1977. Grondklassifikasie, 'n Binomiese
sisteem vir Suid-Afrika. Govt. Printer, Pretoria.
MUELLER-DOMBOIS, D. & ELLENBERG, H. 1974. Aims and methods of
vegetation ecology. Wiley, New York.
POTGIETER, P.J. (ED.), LE ROUX, P.A.L., VAN BILJON, J.J., VAN DER
RYST, C., KRIGE, S. & PRETORIUS,T. 1995. Regional overview study of
the free State. Commissioned by the Land and Agricultural Policy
Centre, Bloemfontein.
SCHEEPERS,J.C. 1975. The plant ecology of the Kroonstad and Bethlehem
areas of the Highveld Agricultural Region.D.Sc. thesis, University of
Pretoria, Pretoria.
SCHEEPERS, J.C. 1986. Grassland Biome Project: Proceedings of the
workshop on the classification and mapping. Ecosystems Prog. Rep. 16:
1-31.
SCHULZE, R.E. & MCGEE, O.S. 1978. Climatic indices and classification in
relation to the biogeography of southern Africa. pp. 19-52. In:
Biogeography and ecology of southern Africa. Werger, M.J.A. (Ed.). The
Hague: W. Junk.
SOIL CLASSIFICATION WORKING GROUP 1991. Soil classification. A
taxonomic system for South Africa. Memoirs on the Agricultural Natural
Recourses of South Africa No 15. Department of Agricultural
Development, Pretoria.
STRAHLER, A.N. 1975. Physical geography. Fourth edition. John Wiley and
Sons, Inc., New York.
262
VAN DERWALL, R.W.E. 1976. Die neerslagklimaat van die Oranje-Vrystaat.
Unpublished M.Sc. thesis. University of the Orange Free State,
Bloemfontein.
VAN DERWALT, P.T. 1992. Wetlands. Custos 6: 22.
VAN OUDTSHOORN, F.P. 1991. Gids tot grasse van Suid-Afrika. Briza
Publications, Arcadia, Pretoria.
VAN ZYL, D.P. 1966. Voorligtingkundige navorsing in die Bo-Oranje-
Opvanggebied: 'n Samevattende verslag van die Bo-Oranje-Sleutelprojek.
Dept. Agric. Tech. Serv. Gov. Printer, Pretoria.
WALMSLEY, R.D. 1988. A description of the wetlands research programme.
S. Afr. Nat. Sci. Prog. Rep. 145: 1-26.
WETZEL, R.G. 1983. Limnology. 2nd ed. Saunders College Publishing. New
York.
WOODWARD, F.t. & WILLIAMS, B.G. 1987. Climate and plant distribution
at global and local scales. Vegetatio 69: 189-197.
263
CHAPTER 10
Vegetation ecology of the southern Free State
Vegetation ecology of the southern Free State: Pan vegetation
264
CHAPTER 10
VEGETATION ECOLOGY OF THE SOUTHERN FREE STATE: PAN
VEGETATION
10.1 INTRODUCTION
South Africa is an arid country of which 65% of the total area receives a
mean annual precipitation of less than 500 mm (Cowan 1991 l. According
to Morant (1983), wetland habitats in southern Africa have received little
attention in the past. Little research or conservation efforts have been
focused on pan ecosystems and despite their unique nature there has been
an underestimation of their conservation value.
Pans are common in many of the world's arid zones. In Africa, south of
the equator, pans occur from Za'li'e in the north to South Africa in the
south and from Namibia in the west to Mozambique in the east. The
greatest concentration is,. however, to be found in the southern
Kalahari/northern Cape/western Free State region (Seaman 1987) whete
the mean annual precipitation is less than 500 mm.
To the casual traveller through the drier, western parts of South Africa,
the shallow and usually waterless depressions in the veld are of little
interest. But appearances can be deceptive. Such depressions can be
surprisingly common. In fact, in pioneer days transport routes in the
western Free State followed lines of pan abundance because of the water
which they provided. They are important components of the terrestrial
ecosystems of the region and, when they hold water, contain a uniquely
fascinating biota. Despite the ecological importance of such temporary
water-bodies, one can find very little about them in either learned or
popular texts. It is obvious, however, that the relative lack of permanent
waters in arid regions makes temporary water-bodies very important to the
ecological functioning of such regions (Seaman 1987).
265
DEFINITION OF PANS
Some controversy has surrounded the definition of various wetland types
(Morant 1983, Walmsley & Botten 1987), but endorheic (closed or no
outlet) pans (Hutchinson et al. 1932, Geldenhuys 1982, Noble & Hemens
1978) are relatively easily defined ecosystems. Pans are shallow, even
when fully inundated and are seldom more than about three metres deep.
Typically their shape is circular to oval (Zaloumis 1987). Goudie & Thomas
(1985) refer to pans as "small closed basins". Lancaster (1979) described
southern Kalahari pans as "dry or ephemeral lakes, 0.3 - 7 km2 in area
which may have bare clay or more or less vegetated surfaces, contained in
isolated enclosed depressions of 5-20 m deep with sizes of 2 - 16 km2."
An early attempt to classify pans was based simply on their distance
from the coast. Du Toit (1927) classified, pans of South Africa as being
either coastal or inland pans. The first classification of pans in relation to
vegetation was applied to the pans in the Lake Chrissie area (Hutchinson
et al. 1932). The following categories were distinguished: Setrous pans,
reed (Phragmites) pans, Melosira-Cyanophyceae pans, Potamogeton
livingstonei pans, Nodularia pans and vegetation-less pans.
Noble and Hemens (1978) gave a general overview of several pan
types in South Africa on the basis of physical characteristics and faunal
and floral composition. These included salt-pans, temporary pans, grass
pans, sedge pans, reed pans :and semi-permanent. pans. A more
comprehensive classification of pans was devised by Geldenhuys (1982).
He distinguished six types of pans in the Free State on the basis of
presence of emergent-vegetation arid in relation to utilization of the pans
by water birds, both of which are dependent on the average duration of
inundation. These are bare, sedge, scrub, mixed grass, closed and open
Diplachne pans.
It is clear that though relatively little work has been done on pans, they
are of ecological value and scientific interest. According to Geldenhuys
(1982) I annual rainfall is the best indicator of the number of pans being
flooded for a significant period of time. The existence of pans depends
266
entirely on the water regime and factors such as rainfall intensity,
evaporation rate and groundwater level, all influence the duration of
inundation (Cowan 1995).
THE FLORA OF PANS
Although several of the above classification schemes have been loosely
based on the vegetation associated with pans, no published analyses of
the vegetation of pans in South Africa exist. The only comprehensive,
although unpublished, survey of the vegetation of a pan is that of Zimbatis
(1975) covering Baberspan.
Geldenhuys (1982) found the less vegetated pan types to be more
common in the drier south-western Free State, while the more vegetated
types were more common in wetter areas, although both types occurred
throughout, often in close proximity.
DISTRIBUTION OF PANS
According to Le Roux (1978) most of the pans in the Free State are
situated on the arid side of the 550 mm annual rainfall isohyet. Le Roux
(1978), however, considered rainfall as a proportion of evaporation to be
more significant in influencing the maintenance of pans. He felt that these
isolines correlated more Closely with pan distribution (Cowan 1995).
Seaman (1987) compiled a map indicating the greatest concentration of
natural pans in the Free State. According to him most of the pans in the
southern Free State are situated in the dry south-western Free State
between Bloemfontein, Petrusburg and Fauresmith (Figure 10.1). Also
indicated in Figure 10.1 are 20%, 30% and 40% isolines indicating annual
rainfall expressed as a percentage of the annual evaporation (Le Roux
1978).
Concerning geology, most pans in the Free State are on Ecca Series,
followed by Beaufort and Stormberg Series (Le Roux 1978). According to
267
Acocks (1988), the soil on the flats around pans in the western Free State
is turfy with little or no rocks present. In his survey on the origin and
forming of pans in the western Free State, De Bruiyn (1971) came to the
following conclusion: DOf prime importance in the formation of pans is the
presence of dolerite basin structures which, due to the resistance of
dolerite to weathering, lead to the development of local inward drainage
patterns. The inward drainage causes rainwater to accumulate in these
basins and dissolved salts are concentrated when the water evaporates.
The high concentration of salts causes mechanical weathering of the
.sediments due to crystallization and thermal expansion, thus producing
disaggregated debris for removal by wind or water action. The prevailing
low rainfall and high temperatures cause a rapid concentration of salts
derived from those originally present in the Dwyka and Ecca sediments.
After weathering the debris is removed by wind or water, thus exposing
the next layer to weathering and erosion. This is the process that
produces the typical flat floors of the pans, parallel to the bedding of the
underlying sedimentary rocks. n
10.2 STUDY AREA
The study area is located in the dry western parts of the southern Free
State where annual rainfall expressed as a percentage of the annual
.evaporation is half of that in the south-eastern parts. The location of the
study area in relation to towns in the southern Free State is shown in
Figure 10.1.
Slow-draining streams and waterbeds are scarce owing to the flatness
of the study area. The topography comprises a mosaic of flat, slightly
undulating and undulating terrain (land Type Survey Staff, in Press).
Isolated hills and ridges occur. A detailed description of the study area
was given elsewhere in this dissertation (Chapter 2).
268
10.3 METHODS
Relevés were compiled in 35 stratified sample plots. Plot sizes were fixed
at 25 m2. In each sample plot, the total floristic composition, using the
Braun-Blanquet cover-abundance scale (Mueller-Dombois & Ellenberg
1974) was noted. Environmental information included geological
formation, soil type and rockiness of the soil surface.
Two-way indicator species analysis (TWINSPAN) (Hill 1979 b) was
applied to the floristic data set in order to derive a first approximation of
the vegetation types of the area. Refinement of this classification was
done by the application of Braun-Blanquet procedures. The results are
presented in a phytosociological table (Table 10.1). The floristic data set
was further subjected to an ordination algorithm, Detrended
Correspondence Analysis (DECORANA) (Hill 1979 a), to determine
vegetation gradients and the relationship with environmental variables.
Taxon and author names conform to those of Arnold & DeWet (1993) and
water birds were identified from Sinclair (1987).
10.4 RESULTS AND DISCUSSION
The analysis resulted in the recognition of nine plant communities, which
can be grouped into three major community types. The· hierarchical
classification is as follows:
1 Dip/aehne fusea Community in non-saline pans
1.1 Diplaehne fusea-Eragrostis eurvula Sub-community
1.2 Diplaehne fusea Sub-community
2 Sa/sola g/abreseens Community in saline pans
2.1 Salsola glabreseens Sub-community
2.2 Salsola glabreseens-Atriplex nummularia Sub-community
2.3 Salsola glabreseens-Suaeda frutieosa Sub-community
2.4 Sa/so/a glabreseens-Eragrostis bieolor Sub-community
2.5 Salsola glabreseens-Sporobolus tenellus Sub-community
269
3 Sporobo/us tenellus-Chenopodium a/bum Community
DESCRIPTION OF THE COMMUNITIES
1 Dip/achne fusca Community in non-saline pans
This community is generally found in the central zones of pans and is the
first to be submerged after good rains. The landscapes are mostly flat with
no rocks visible on the ground surface. The trampling effect and grazing
pressure exerted on this community by cattle and sheep is clearly
recognizable. The soil is generally moderately to well drained. According to
Fuls (1993), the Dip/achne fusca pan and vlei vegetation in the
Wesselsbron-Welkom area is characterized by the predominance of silt and
non-swelling kaolinitic clays. This is also the case in the southern Free
State.
According to Cowan (1995), the differences in bird communities
between the three pan types (reed, sedge and open pans) in the lake
Chrissie area relate to differences in the habitats offered by each pan type.
Numerous water birds were spotted within the Dip/achne fusca Pan
Community and include Egyptian Goose (A/opochen aegyptiacus), South
African Shellduck (Tadoma cana), Yellow-billed duck (Anas undu/ata) and
Red-billed Teal (Anas erythrorhyncha). The presence of these birds
conform to that spotted by Geldenhuys (1982) in open Dip/achne pans in
the western Free State.
The rhizomatous swamp grass, Dip/achne fusca (species group B, Table
10.1), is the only dominant species present. D. fusca is also prominent in
the pans in the northern Free State described by Fuls (1993). This mat-
forming, stoloniferous species appears to be annual, "disappearing" during
the dry season or prolonged dry spells, only to re-appear within a week or
so after substantial rain (Fuls 1993).
'-----------------------------------_. - -
270
Two distinct sub-communities characterize this community (Table
10.1 ).
1.1 Diplachne fusca-Eragrostis curvula Sub-community
This grassland is generally found on the edges of clay pans where loose
sand overlies the clayey soil (duplex soils). The soil is calcareous-clayey
with a high base status and generally deeper than 300 mm (Ae land type).
Standing water occurs periodically for weeks after good rains.
Although degradation of the vegetation is evident, Diplachne fusca
(species group B) has a high cover-abundance. Only five species, with
Eragrostis curvula and Setaria incrassata the most abundant, differentiate
this sub-community (species group A, Table 10.1). The above-mentioned
water birds were all observed in this sub-community.
1.2 Dipteenne fusca Sub-community
This sub-community is found in the central areas of pans where the soils
are generally deep (> 500 mm deep) and clayey. The sandy layer
mentioned within the Diplachne fusca-Eragrostis curvula Pan Grassland is
absent here. Bezuidenhout (1995) described a similar plant community in
the Graspan-Holpan section of the Vaalbos National Park. near Kimberley
in the Northern Cape. The Diplachne fusca Variant, he described. is
associated with the poorly drained, moderately deep, clayey (> 25% clay
content - A- & B-horizons) soil of the pans. According to Gibbs Russe" et
al. (1990) and Van Oudtshoorn (1991), D. fusca is always found near to
or in fresh or brackish water. Periodically standing water occurs and the
soil is poorly drained. Noteworthy is the exceptionally low species
diversity with homogeneous dominance of Diplachne fusca (species group
B). This sub-community differs from the Diplachne fusca-Eragrostis curvula
Pan Grassland by the total absence of species from species group A (Table
10.1). The habitat is fairly unstable, owing to seasonal flooding and
drying, which, together with the frequent overgrazing of these sites
271
caused the advanced state of degradation of the vegetation present. No
water birds were spotted.
2 Salsola glabrescens Community in saline pans
The Salsola glabrescens Pan Vegetation occurs on relatively poorly drained
situations on the fringes of wetter drainage lines and other pan-bottomland
situations. The soils of the undulating areas are shallower « 300 mm
deep) and the surface is often covered with calcareous stones.
This community is characterized by the absence of Diplachne fusca
(species group B) and the strong presence of Salsola glabrescens (species
group F, Table 10.1).
Six distinct sub-communities are recognizable (Table 10.1).
2.1 Salsola glabrescens Sub-community
The Salsola glabrescens dry pan vegetation occurs on saline-calcareous
soil which is virtually covered with fine gravel. The vegetation is heavily
overgrazed and the surface trampled. Road-building operations (road
construction) affect most of the vegetation. According to Cowan (1995),
over 40% of the pans in the Gauteng (the former PWV region in the
central Transvaal) are affected by this practice. According to him pans are
frequently seen as "lines of least resistance" by road planners.
The small WOOdyshrublet, Salsola glabrescens (species group F), is the
onlv species present. The average height of these shrublets do not exceed
0.3 m. Overgrazing of vegetation frequently occurs and the habitat is
infested by termites.
2.2 Salsola glabrescens-Atriplex nummularia Sub-community
272
The Sa/so/a g/abreseens-Atrip/ex nummu/aria Sub-community occurs on
flat landscapes on the edges of salt pans with fine gravel and calcareous
stones visible on the surface. The vegetation is severely disturbed and
standinq water occurs in lower-lying areas. These environmental
conditions provide a moist environment and only three diagnostic species
occur (species group C, Table 10.1). Atrip/ex nummu/aria and A.
semibaeeata seldom grow higher than 0.3 m.
2.3 Selsole g/abreseens-Suaeda frutieosa Sub-community
This sub-community is encountered in the lower-lying areas of salt pans
(brackish soil). Like the setsot» g/abreseens-Atrip/ex nummu/aria Pan
Vegetation, this sub-community is severely disturbed and trampled.
Erosion also occurs, but no stones are visible on the surface.
Diagnostic species include those listed in species group D (Table 10.1)
with Suaeda frutieosa, Atrip/ex erosa and Zygophyllum simp/ex the most
important (Table 10.1).
2.4 Sa/so/a g/abreseens-Sporobo/us ioe/ados Sub-community
Thls : pan grassland is restricted to seasonally wet, poorly drained
situation,s. The calcareous soils are brackish and often show vertic or
melanic properties. Alluvium, silt and gravel can be observed at many
localities. The habitat is fairly unstable owing to seasonal flooding and
drying. No gravel occurs on the soil surface.
The vegetation is characterized by the· absence of species of species
groups A-D and the presence of species of species groups E, F and H
(Table 10.1). Eragrostis bicotor, Sporebolus toeledos (species group E),
Sa/so/a g/abrescens (species group F) and Sporobo/us tenellus (species
group H) characterize this vegetation unit.
273
2.5 Salsola glabreseens-Sporobolus tenellus Sub-community
This grassland is found in severely eroded pans where wet calcareous soil
occurs. During the rainy season, this sub-community is seasonally
waterlogged. The vegetation is mostly disturbed and moderately over-
utilized.
Salsola glabreseens {species group F} and Sporobolus tenellus {species
group H} dominate the vegetation. This sub-community has virtually the
same species composition as the Salsola glabreseens-Sporobolus ioclados
Sub-community with the absence of Eragrostis bieolor (species group E)
the only exception (Table 10.1).
3 Sporobolus tenellus-Chenopodium elburn Community
The Sporobolus tene/lus-Chenopodium album Community is found on the
edges of permanently waterlogged pans. The depth of these pans varies
from 100 mm to 300 mm. The vegetation of these areas is usually
overgrazed and the calcareous-stony soil trampled. The predominant soil
type is the vertic Rensburg form.
This community is characterized by the species listed in species group
G (Table 10.1) of which Chenopodium album, Portulaea oleraeea and the
small sedge, cvaerus laevigatus, are the most conspicuous differentiating
species. The dwarf grass species Saorobotus tenellus (species group H) is
also conspicuous.
ORDINATION
The distribution of all the plant communities along the first and second
axes of the ordination is presented in Figure 10.2. The third and fourth
axes contribute very little to the environmental interpretation of the
communities and are therefore omitted. The vegetation gradient on the
first axis is primarily associated with a soil texture gradient. Diplachne
274
fusca Pan Vegetation to the left occurs on sandy-clayey (duplex) soils with
a rockiness of less than 10%. Communities associated with rocky-clayey
soils with a rockiness of > 20 % are to the right. Dry and moderately dry
plant communities are to the top of the diagram. Plant communities which
are more adapted to moist and wet conditions with poorly drained soils are
to the bottom of the diagram (axis 2).
In the second ordination (Figure 10.3), the same data set was applied
but relevés containing Diplachne fusca (indicated by "a" in Figure 10.2) on
clayey soil were excluded. This was done because of the big difference
between clay pans (indicated by "a in Figure 10.1) and the rest of the pan
vegetation (Figure 10.2). The distribution of the plant communities is
illustrated along the first and .second axes of the ordination. Axis 1
illustrates a moisture gradient with the permanently waterlogged plant
communities on poorly drained soils to the right of the diagram. Dry and
seasonally waterlogged plant communities on well-drained soils are the
left. The soils to the right of the diagram are generally deeper than those
to the left. No clear discontinuity is associated with axis 2 of the diagram
(Figure 10.3).
DISCUSSION
The eight plant communities. identified are not strictly related to specific
environmental variables, but are rather the products of combinations of
variables such as soil depth, moisture, soil type and clay contents. A clear
difference, however, between Diplachne fusca pans (clayey soils) and
mixed grassland pans on rocky-clayey soils exists (Figures 10.2).
Diplachne fusca, Salsola glabrescens and Sporobotus tenellus are the
most prominent species associated with pans in the southern Free State.
Much remains to be done concerning the conservation of pans.
Management strategies aimed' at land in private ownership, as suggested
by Geldenhuys (1982), is as important as land acquisition for formal
nature reserves. But how does one conserve pans? On the one hand,
275
farmers (because most pans are on their land) and the public in general
should be encouraged to regard pans as vital and interesting parts of the
ecosystem. On the other hand, "panveld" , as it is colloquially called,
deserves to be conserved as part of a larger terrestrial-aquatic unit. This
latter course has, to an extent, been followed inadvertently in the private
conservation areas like Rooipoort near Kimberley in the North Cape. This is
also the case on the Defence Force property, De Brug, west of
Bloemfontein. Both properties are close to 30 000 hectares in size
(Seaman 1987). However, some of the larger, and perhaps a suite of
representative, pans should be given formal conservation protection if for
no other reason than for their tourism and education potential. These
protected pans could also provide baseline information against which
status of pans in unprotected areas could be compared. Therefore
consideration should be given for including many of the more important
pans in the formal nature reserve system, including municipal reserves
(Cowan 1995). Long-term resource conservation will only be·effective if
ecological boundaries are incorporated first and a proper management and
conservation strategy be applied to these areas.
This delineation of the plant communities and associated habitats of the
pans in the southern Free State should be used as the basis for future
management and conservation of these areas.
276
10.5 REFERENCES
ACOCKS, J.P.H. 1988. Veld types of South Africa: 3 rd edn. Mem. bot.
Surv. S. A fr. 57: 1-146.
ARNOLD, T.H. & DE WET, B.C. 1993. Plants of southern Africa: names
and distribution. Mem. bot. Surv. S. Afr. 62: 1-825.
BEZUIDENHOUT, H. 1995. An ecological study of the major vegetation
communities of the Vaalbos National Park, Northern Cape. 2. The
Graspan-Holpan section. Koedoe. 38 (2): 65-83.
COWAN, G.t. 1991. Wetlands enjoy high priority for protection. South
African Wetlands 1: 4-7.
COWAN, G.t.· (Ed.) 1995. Wetlands of South Africa. S.A. Wetlands
Conservation Programme Series. Dept. of Environmental Affairs and
Tourism. Pretoria.
DE BRUIYN, H. 1971. 'n Geologiese studie van die panne van die
westelike Oranje-Vrystaat. M.Sc. thesis, University of the Orange Free
State, Bloemfontein.
DU TOIT, A.L. 1927. The geology of South Africa; Oliver & Boyd,
Edinburgh.
FULS, E.R. 1993. Vegetation ecology of the northern Orange Free State.
Unpublished Ph.D. dissertation. University of Pretoria, Pretoria.
GELDENHUYS, J.N. 1982. Classification of pans in the western Orange
Free State according to vegetation structure, with reference to
avifaunal communities. S. Afr. Tydskr. Natuurnav. 12: 55-62.
GIBBS RUSSELL, G.E., WATSON, L., KOEKEMOER, .M., SMOOK, L.,
BARKER, N.P., ANDERSON, H.M. & DALLWITZ, M.J. 1990. Grasses of
southern Africa. Mem. bot Surv. S. Afr. 58: 1-437.
277
GOUDlE, A.S. & THOMAS, D.S.G. 1985. Pans in southern Africa with
particular reference to South Africa and Zimbabwe, Zeitschrift tur
Geomorpbotoaie NF 29: 1-19.
HILL, M.O. 1979 a. DECORANA - A Fortran programme for detrended
correspondence analysis and reciprocal averaging. Department of
Ecology and Systematics, CornelI University, Ithaca, New York.
HILL, M.O. 1979 b. TWINSPAN - A Fortran programme for arranging
multivariate data in an ordered two-way table by classification of the
individuals and attributes. Department of Ecology and Systematics,
Come" University, Ithaca, New York.
HUTCHINSON, G.E., PICKFORD, G.E. & SCHUURMAN, J.F.M. 1932. A
contribution to the hydrology of pans and inland waters of South
Africa. Archiv tur Hydrobiologie 24: 1-154.
LANCASTER, I.N. 1979. Quaternary environments in the arid zone of
southern Africa. Occasional paper No. 22, Env Studies, University of
the Witwatersrand, Johannesburg. pp. 1-77.
LAND TYPE SURVEY STAFF (IN PRESS). Land types of the maps 2924 -
Koffiefontein and 2926 - Bloemfontein. Mem. agric. nat. Resources S.
Atr. No. 14.
LE ROUX, J.S. 1978. The origin and distribution of pans in the Orange
Free State. S. Atr. Geogr. 6: 167-176.
MORANT, P.D. 1983. Wetland classification towards an approach for
southern Africa. J. Limnol. Soc. S. Atr. 9: 76-84.
MUELLER-DOMBOIS, D. & ELLENBERG, H. 1974. Aims and Methods of
Vegetation Ecolo·gy.Wiley, New York.
~------------------------------------------------------------------.
278
NOBLE, R.G. & HEMENS, J. 1978. Inland water ecosystems in South
Africa - a review of research needs. S. Afr. Nat. Sci. Prog. Rep. 34: 1-
150.
SEAMAN, M.T. 1987. Panne van die Oranje-Vrystaat. African Wildlife
41 (5): 237-238.
SINCLAIR, I. 1987. Field guide to the birds of southern Africa. 3 rd edn.
Struik, Cape Town.
WALMSLEY, R.D. & BOTIEN M.L. (Eds.) 1987. Proceedings of a
Symposium on the Conservation of Wetlands in South Africa. Report.
Series No 28, Ecosystem. Programmes, Foundation for Research
Development, CSIR, Pretoria.
WEATHER BUREAU, 1965. Climate of South Africa. General survey. Part
8. WB 28. pp 330. Govt. Printer, Pretoria.
ZALOUMIS, E.A. 1987. Don't pull the plug! African Wildlife 41 (5): 216-
217.
ZIMBATIS~ N. 1975. A floristic survey of provincial nature reserves,
Transvaal. Baberspan Nature Reserve. Unpubl. report on project No
TN 6.3.3. Transvaal Division of Nature Conservation. pp. 1-8.
279
CHAPTER 11
Vegetation ecology of the southern Free State
Vegetation classes of the southern Free State
280
CHAPTER 11
VEGETATION CLASSES OF THE SOUTHERN FREE STATE
11 .1 INTRODUCTION
Despite a number of broad classifications of the vegetation of southern
Africa (Bolus 1886, 1905; Marloth 1906; Pole-Evans 1936; Acocks 1953,
1988; White 1976, 1983; Werger 1978; Rutherford & Westfall 1986, Low
& Rebeto 1996) I there is still a shortage of more detailed phytosociological
studies of the South African flora (Scheepers 1986).
There were numerous attempts to distinguish vegetation units in South
Africa (Werger 1978)., Each vegetation map differed from the previous one,
as the knowledge on the flora expanded and different classification
approaches were developed. The present floristic knowledge has lead to the
phytochorological subdivision of the continent (Werger 1978) r but there is
stili the need for more detailed studies on the phytosociology of the South
African flora (Scheepers 1986). Since Mentis & Huntley (1982) stated the
necessity of research work in the Grassland Biome, a pbvtosocioloqical
research programme on the phytosociology and syntaxonomy of the Biome
has been conducted.
The existing broad classifications are inadequate for detailed or regional
agricultural and conservational planning and management of the biotic
resources. Reclassification and mapping of the vegetation according to
applicable scales is a priority (Scheepers 1986) and has been identified as
such by the Grassland Research Centre (Department of Agricultural
Development) .
Subsequently a research programme on the detailed phytosociological
synthesis of the vegetation of the Grassland Biome was initiated in 1986
(Scheepers 1986) and several phytosociological studies were launched to
describe the vegetation of the Grassland Biome {i.e. Bezuidenhout 1988,
1993; Turner 1989; Kooij 1990 (a, b & c); Du Preez 1991; Matthews 1991;
281
Breytenbach 1991; Malan 1992; Coetzee 1993; Eckhardt 1993; Fuls 1993
and Myburgh 1993). The vegetation of the southern Free State represents a
major part of this biome.
The phytosociological synthesis of the vegetation of the southern Free
State forms part of the final objective to compile a comprehensive
synecological and syntaxonomical synthesis of the vegetation of the
Grassland Biome of South Africa. Several major vegetation classes were
identified and these classes should form the basis for future detailed
synecological and syntaxonomical studies.
11 .2 METHODS
Compatible phytosociological data done by other phytosociologists, were
obtained from the entire study area. These included:
* Association analysis of Thaba 'Nchu mountain (Roberts 1966);
* Braun-Blanquet classification of the Botanical Gardens of the Free State
.(MOller 1970);
* Compatible Braun-Blanquet classifications of the Upper Orange River
Valley and the Tussen die Riviere Game Farm (Werger 1973 a & b);
* Vegetation ecology of Naval Hill (Du Preez 1979);
* Phytosociology of the Rolfontein Nature Reserve (Jooste 1980);
* Tree communities in the Bloemfontein area (Rossouw 1983);
* Phytosociology of the Bloemfontein west District (Malan 1992);
* Relevés encountered in the Soetdoring Nature Reserve; and
* New relevés compiled in the southern Free State by the present author.
The association analysis carried out by Roberts (1966) on the Thaba
'Nchu mountain is not comparable to a Braun-Blanquet classification. His
data was therefore only used as presence-absence data in the synoptic data
of the synthesis. Du Preez (1991) also made use of the presence-absence
data of the association analysis association analysis carried out by
Scheepers (1975) in the Bethlehem area.
282
All the above individual classifications resulted in the identification of
394 plant communities, compiled from 2 370 relevés, including more than
700 species (species list is stored in the database of the Main Frame
Computer' System, University of the Orange Free State). A procedure of
successive approximation, including the recently proposed method for large
data sets (Bredenkamp & Bezuidenhout 1995), was applied in this study:
Synoptic tables were constructed for each individual phytosociological
classification, using the standard constancy classes (Whittaker 1978). In
this way each community from each individual phytosociological
classification was summarized as a single column (synrelevé) in a synoptic
table. Rearrangement of this table by TWINSPAN (Hill 1979 al and
refinement of the resulting synrelevé classification by Braun-Blanquet
procedures (Bredenkamp & Bezuidenhout 1995), brought all the related
synrelevés (plant communities), identified by, different researchers, in
different studies from different regions in the southern Free State,
effectively together in a single synoptic table (Table 11.1) comprising 394
communities identified in the various investigations over the entire study
area.
Sixteen' major vegetation types were identified and considered to
represent phytosociological classes. Due to the enormous dimensions of the
synoptic table (394 synrelevés), each of the 16 vegetation types was
further reduced to a single column by using 20% frequency intervals for the
species encountered in the various synrelevés within a vegetation type.
Table 11.1 clearly reveals the differential and character species of each
class. Differential species are those preferential to a specific community and
therefore distinguish that particular community from other floristically related
communities, but these species may at the same time, be equally well or
even better represented in other communities (Werger 1973 a). The
differential species are indicated by .shaded columns.
Character species are but a special case of differentiating species. These
character species are of great diagnostic importance and can be classified
into exclusive, selective and preferential species (Werger 1973 al. The
283
character species, referred to as diagnostic species in text, are restricted to
a particular class and are indicated by a single column (Table 11.1).
Species which do not differentiate between the communities are called
accompanying species (Werger 1973 a).
An ordination algorithm, DECORANA (Hill 1979 b), was also applied to
the synoptic data set to show environmental gradients between the different
communities.
Taxa names conform to those of Arnold & De Wet ('993). No
syntaxonomic names are attached to these classes pending better research.
11.3 RESULTS AND DISCUSSION
The vegetation of the southern Free State is broadly classified as the
Themeda triandra-Eragrostis lehmanniana Grassland (Table 11.1). This
grassland represents the natural climatic climax over most of the central and
western Free State (Bayer 1955, Tainton 1984). The vegetation of the
Grassland Biome is physiognomically monolithic and is characterized by
strong dominance of hemicryptophytes of the Poaceae. Canopy cover is
moisture dependent and decreases with mean annual rainfall (Rutherford &
Westfall 1994). According to Rutherford & Westfall (1994) the vegetation
of the Nama-Karoo Biome is : dominated by chamaephytes and
hemicryptophytes and can be described as a grassy, dwarf shrubland
(Edwards 1983). The dominance of graminoids is consistent throughout,
except for some rocky outcrops which are generally dominated by woody
species. Grassland and karroid vegetation dominate the biggest part of the
study area, with disturbed/overgrazed areas also prominent. The Grassland-
Nama-Karoo interface (ecotone) is characterized by grassland which is
invaded by karroid dwarf shrubJand. According to Vorster & Roux (1983)
succession of plant composition in the Nama-Karoo-Biome is usually taken
to start after disturbance by overgrazing. The usual progression, given a
significant reduction in grazing pressure and a suitable distribution of rainfall
284
(Vorster & Roux 1983), is a steady increase in hemicryptophyte cover and a
more variable decrease in chamaephyte cover (Rutherford & Westfall 1994).
Three grassland types are distinguishable in the southern Free State: Dry
Sandy Highveld Grassland of the plains in the dry western parts
(Bredenkamp & Van Rooyen 1996 a), Moist Cool Highveld Grassland in the
central-eastern part of the highveld in the Free State (Bredenkamp & Van
Rooyen 1996 b) and Moist Cold Highveld Grassland (Bredenkamp et al.
1996).
The Dry Sandy Highveld Grassland occurs where the summer rainfall is
erratic with an average of 450 mm per annum. Temperatures vary between
-11 aC and 41 aC with an average of 18 aC. The soils are deep, red to
yellow, apedal, aeolian sand, often covering limestone. This is a grassland
which merges with the bordering Kalahari Thornveld to the west. A fe~
Acacia karroo trees occur only occasionally along watercourses. West of
Bloemfontein, affinity to Karoo vegetation can be seen in plant communities
dominated by dwarf shrubs, including Chrysocoma ciliata, Fe/icia muricata,
He/ichrysum pentzioides, Nenax microphylla, Pentzia incana, Rhus cutete.
Sa/so/a kali, Wa/afrida densiflora and W. saxati/is. The presence of Karoo
elements in the western parts probably represent outliers of Karoo
vegetation, but this should not necessary be considered as encroachment
(Bredenkamp & Van Rooyen 1996 a).
The Moist Cool Highveld Grassland, generally referred to as
Cymbopogon- Themeda Veld (Acocks 1988) occurs in areas where the
rainfall varies from 600-700 mm per annum, occurring in summer.
Temperatures vary from .:11 aC to 38 aC, with an average of 17°C. Deep,
red (Hutton) and yellow (Clovelly) soils predominate. Grazing here is
important, but overgrazing converts this grassland to a Karoo type. The
presence of Karoo elements in degraded sites is often seen as signs of
Karoo encroachment into the Grassland Biome. In pristine condition
Themeda triandra dominates entirely (Bredénkamp & Van Rooyen 1996 b).
Other - grasses often encountered include Triraphis andropogonoides,
Eragrostis superba, Brachiaria serrata, Elionurus muticus, Heteropogon
contortus, Cymbopogon p/urinodis and Setaria sphace/ata.
285
This grassland was studied by numerous phytosociologists like
Bredenkamp et al. (1989), Kooij et al. (1992), Fuls et al. (1993), Eckhardt et
al. (1993 a) and Coetzee et al. (1994).
The Moist Cold Highveld Grassland of the southern Free State is
restricted to the Zastron Area. The rainfall ranges from 700-800 mm per
annum, occurring mainly in summer. Temperatures vary between -13°C
and 35°C, with an average of 14 °C. The soils are generally deep (deeper
than 300 mm) yellow and grey sandy-loam soils derived from sandstones
and shales of the Beaufort Group. This is a moderately dense grassland
dominated by Cymbopogon plurinodis, Elionurus muticus, Eragrostis curvula,
Setaria sphacelata and Themeda triandra. Typical grasses of this grassland
include Andropogon appendiculatus, Aristida junciformis, Eragrostis
capensis, E. plana, Helictotrichon turqidutum, Microchloa caffra and
Tristachya leucothrix (Bredenkamp et al. 1996).
This grassland was surveyed bv phytosociologists like Lubke et al.
(1988), Du Preez (1991), Du Preez & Bredenkamp (1991), Eckhardt et al.
(1993 a) and Fuls (1993).
The most prominent grass species encountered throughout the southern
Free State are Aristida congesta, A. diffusa, Digitaria eriantha, Eragrostis
curvula, E. lehmanniana, E. obtusa, Eustachys paspaloides, Themeda
triandra and Tragus koelerioides. Also present but less prominent are
Cymbopogon plurinodis, Eragrostis chloromelas, E. nindensis, E. superba,
Heteropogon contortus and Sporobolus fimbriatus (Table 11.1).
Among the karroid vegetation Berkheya onoporditotie, B. pinnatifida,
Chrysocoma ciliata, Felicia muricata, Hertia pal/ens, Melolobium candicans,
Protasparagus laricinus and Walafrida saxatilis are the most prominent
(Table 11. 1).
Trees and shrubs occur widespread but scattered in the southern Free
State. The most important are Acacia karroo, A. mel/ifera, Boscia
albitrunca, Buddleja saligna, B. salviifolia, Diospyros austro-africana, D.
L- ~
286
Iycioides, Ehretia rigida, Euclea crispa subsp. ovete; Olea europees, Rhus
burchellii, R. lancea, Rhigozum obovatum, R. trichotornum and Ziziphus
mucronata (Table 11.1).
CLASSIFICATION
The classification resulted in the recognition of 16 phytosociological classes
(Table 11.1):
Class 1: Leucosidea sericea-Stoebe plumosa Mixed Afro-montane fynbos
vegetation of the eastern mountains
Class 2: Rhus erosa shrubland of the rocky outcrops of the dry south-
vvestern Free State
2.1: Rhus erosa-Aloe ferox transitional shrubland between the Afro-montane
fynbos vegetation and the shrubland communities of the extreme dry
western Free State shrubland
2.2: Euclea crispa-Buddleja saligna woodland of the dry south-vvestern Free
State
2.3: Argyrolobium lanceolatum-Anacampseros lanceolata shrubland of the
.False Upper Karoo
3: Eragrostis lehmanniana-Chrysocoma ciliata karroid vegetation
3.1: Rosenia humilis-Duthiastrum linifolium dvvarf shrubland
3.2: Hermannia erodioides-Syncarpha argyropsis dwarf shrubland of the
Rolfontein Nature Reserve
Class 4: Phaeoptilum spinosum-Zygophyllum giltillanii shrub and dwarf shrub
communities of the rocky soils of the western Upper Orange River Valley
Class 5: Acacia kerroo riparian thicket
Class 6: Acacia me/lifera- Tarchonanthus camphoratus shrubland of the
rocky outcrops
6.1 : Acacia tortilis-Acacia hebeclada shrubland of the lovv-Iying rocky
outcrops
6.2: Phyllanthus parvulus-Abutilon pycnodon shrubland of the higher lying
areas
Class 7: Aristida bipartita-Lactuca serriola moist grassland of Thaba 'Nchu
287
Class 8: Eragrostis plana-Cymbopogon dieterlenii moist grasslands of the
eastern plains
Class 9: Themeda triandra-Cymbopogon plurinodis grasslands of the
western plains.
Class 10: Hertia pallens-Prosopis velutina karroid vegetation of the dry
western Free State
Class 11: Oropetium capense-Anacampseros filamentosa communities on
very shallow soils on dolerite outcrops
Class 12: Phragmites australis-Salix babylonica Riparian vegetation
Class 13: Mariscus congestus-Persicaria serrulata Riparian vegetation
Class 14: Juncus kraussii-Phragmites mauritianus wetland and pan
vegetation
Class 15: Dipteenne fusca-Setaria incrassata Pan vegetation
Class 16: Fingerhuthia africana-Helichrysum pentzioides pan grassland
DESCRIPTION OF THE CLASSES
CLASS 1: LEUCOSIDEA SERICEA-STOEBE PLUMOSA MIXED AFRO-
MONTANE FYNBOS VEGETATION OF THE EASTERN MOUNTAINS
The Leucosidea sericea-Stoebe plumosa Mixed Afro-montane fynbos
vegetation is restricted to the hills and ridges of the Zastron area in the
south-eastern part of the study area. Twelve plant communities encountered
in the south-eastern Free State were included in this class.
This Mixed Afro-montane fynbos vegetation lies in the Moist Cold
Highveld Grassland (Vegetation Type· 40, Bredenkamp et al. 1996). The
rainfall is relatively high and varies between 600 and 800 mm per annum.
Geologically the area is characterized by Molteno and Elliot Formations.
The uppermost formation, namely the Clarens Formation, forms a prominent
cliff on the northern side of Aasvoëlberg Mountain. The endangered Cape
Vulture (Gyps coprotheres) used to breed here. The Molteno Formation, the
first of the Stormberg Group, lies on top of the Beaufort Group. The Elliot
Formation follows contormablv on the Molteno Formation (Dingle et al.
_I
288
1983). The topography of the area consists mainly of continuous hills and
mountains with moderate and high relief, allowing only stock farming and
small-scale crop production.
Generally the soils in the Zastron area are referred to as "Podsolic" (pH
< 7) soils. These soils are generally deeper than "solonetic" [pH > 7 and
contain a high salt ( especially Sodium compounds) content] soils and also
comprises· well-developed horizons. Donga and surface erosion are a
common phenomenon of these soils (Potgieter et al. 1995).
No reconcilable phytosociological classification of this Mixed Afro-
montane fynbos class exists in the southern Free State. Roberts (1966)
mentions Afro-montane fynbos communities from Thaba 'Nchu mountain,
but his classification is derived from an association analysis, which is not
comparable to a Braun-Blanquet classification.
This class, however, is in accordance with the Passerina montana Afro-
montane fynbos communities of the eastern mountains of the Korannaberg,
Thaba 'Nchu mountain and the Drakensberg range described by Du Pree?
(1991). The altitude varies between 1 800 - 2 800 m.
The Leucosidee sericea-Stoebe plumosa Mixed Afro-montane fynbos
communities are characterized by species groups 1 & 2 (Table 11.1). The
most important differentiating species with constancies higher than 40% are .
Leucosidea sericea, Cussonia paniculata, Helichrysum rugulosum and the
exotic rose Rosa eglanteria. The diagnostic species are listed in species
group 2 (Table 11.1). Species with a constancy of higher than 40% include
Euclea cr/spa subsp. crispe, Passerina montana and Stoebe plumosa. Other :
frequently occurring species include Rhus erosa, Olea europees subsp.
africana, Diospyros austro-africana, the small ferns, Cheilanthes eckloniana
and Pellaea calomelanos, Osyris lanceolata (species group 14), Oxalis
corniculata (species group 32), Felicia filifolia (species group 55), the
grasses Heteropogon contortus, Aristida diffusa (species group 61),
Themeda triendre, the trees Rhus burchellii (species group 65) and
Diospyros Iycioides (species group 71) and the shrub Protasparagus laricinus
(species group 76).
289
CLASS 2: RHUS EROSA SHRUBlAND OF THE ROCKY OUTCROPS OF
THE DRY SOUTH-WESTERN FREE STATE
This shrubland includes the shrubland communities of the rocky outcrops of
the relatively dry hills, ridges and slopes to the west of the 500 mm rainfall
isohyet. Also included is the transitional zone between Afro-montane fynbos
vegetation previously mentioned and the usually much drier hills and ridges
in the extreme dry western Free State. The Rhus erosa shrubland of the
western Free State is in accordance with the muItistrata I shrubby Rhus
erosa shrubland described by Du Preez (1991).
The typical habitat consists of dry hills and ridges which are primarily of
dolerite and are underlain by Beaufort and Ecca Formations.
This shrubland includes:
* the syntaxa described by Werger (1973 a) under the Rhoetea erosae;
* the Rhus erosa-Me/inis repens communities, Rhus erosa ...
Stachys burchelliana Community and the Olea europaea-Maytenus
heterophylla communities of the Tussen die Riviere Game Reserve
(Werger 1973 b);
* syntaxa described by Rossouw (1983) from the Bloemfontein
area under the Olea africana Community;
* communities derived from relevés of the Bloemfontein area (Malan 1992);
* Soetdoring Nature Reserve; and
* communities derived from relevés encountered in the southern Free State
by the present author.
The most important species associated with this class are listed in
species groups 14, 47, 54, 60, 61, 64, 65, 71, 75, 76, 77 and 79 of Table
11 .1 . Among the woody species Rhus erosa, Olea europees, Ce/tis africana,
Diospyros austro-africana, Rhigozum obovatum, May tenus po/yacantha,
Rhamnus prinoides, Osyris /anceo/ata, Grewia occidenta/is, Rhus pyroides
subsp. gracilis (species group 14), Ziziphus mucronata, Ehretia rigida
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(species group 54), Fe/icia tilitotie, F. muricata, Rhus ciliata (species group
55), Rhus burchellii, R. /ancea (species group 65), Diospyros /ycioides
(species group 71), Chrysocoma ciliata, Protasparagus /aricinus (species
group 76), P. suaveo/ens, Wa/afrida saxatilis (species group 77) are the
most important (Table 11.1).
Among the grasses Cymbopogon excavatus (species group 14), C.
p/urinodis (species group 47), Enneapogon scoparius (species group 55),
Heteropogon contortus, Aristida congests, A. diffusa (species group 61),
Themeda triandra (species group 65), Hyparrhenia hirta (species group 71),
Eragrostis obtuse (species group 76), Eragrostis lehmanniana (species group
77) and E. curvu/a (species group 80) are abundant (Table 11.1).
The only abundant ferns include Chel1anthes eckloniana and Pellaea
ca/omelanos (species group 14).
This class divides into three different vegetation units (Table 11.1).
2.1: RHUS EROSA-ALOE FEROX TRANSITIONAL SHRUBlAND
BETWEEN THE AFRO-MONTANE FYNBOS VEGETATION AND THE
SHRUBlAND COMMUNiTIES OF THE EXTREME DRY WESTERN FREE
STATE SHRUBlAND
This vegetation unit represents the transitional shrubland communities
between the Afro-montane fynbos vegetation and the shrubland
communities of the extreme dry western Free State. This vegetation unit
consists of ten communities which were encountered near Mayaputi bridge
south of Zastron. Deep Molteno sandstone slopes, nearly always exceeding
15° occur. Southerly and south-easterly facing slopes are the most
prominent habitats. Werger (1973 a), however, found the Rhoo-Aloetum
ferocis mainly on Molteno sandstone and occasionally on Red Beds on
northerly-facing slopes. Werger (1973 a) refers to this vegetation as the
Grewio-Rhoetalia erosae.
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A/oe ferox (species group 3), commonly between 1 and 4 m high, finds
its furthest inland distribution in this area (Werger 1973 a) and serves as the
most important differentiating species. Woody species with constancies
higher than 40% include Euc/ea crispa subsp. ovata (species group 4), Rhus
erosa, Olea europaea, Ce/tis africana, Diospyros austro-africana, Rhigozum
obovatum, Rhamnus prinoides, Grewia occidentalis (species group 14), Rhus
burchellii, R. /ancea (species group 65), Diqspyros /ycioides (species group
71), Chrysocoma ciliata (species group 76), Protasparagus suaveolens,
Wa/afrida saxatilis (species group 77).
The most important grasses are Heteropogon contortus (species group
61), Themeda triandra (species group 65) and Eragrostis curvula (species
group 80).
2.2: EUCLEA CRISPA-BUDDLEJA SALIGNA WOODLAND OF THE DRY
SOUTH-WESTERN FREE STATE
The typical habitat consists of relatively dry hills and ridges and slopes to
the west of the 500 mm rainfall isohyet.
93 Communities were included in this vegetation unit and are:
* the syntaxa described by Rossouw (1983) from the Bloemfontein area
under the Olea africana Community;
* communities derived from relevés of the Bloemfontein area (Malan 1992);
* relevés encountered in the Soetdoring Nature Reserve; and
* communities derived from relevés encountered in the southern Free State.
The diagnostic species restricted to this vegetation unit are listed in
species group 5 and include K/einia /ongiflora, Sisymbrium capense, S.
thellungii and Trachyandra asperata (Table 11.1). Woody species with
constancies of higher than 40% are Euclea crispa subsp. crispa, Budd/eja
saligna (species group 4), Rhus erosa, Olea europaea, Diospyros austro-
africana (species group 14), Rhus ei/iata, Felicia filifo/ia (species group 55),
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Rhus burchellii (species group 65), Chrysocoma ciliata (species group 76)
and Protasparagus suaveolens (species group 77).
Important grasses include Digitaria eriantha (species group 59),
Heteropogon contortus, Aristida congesta, A. diffusa (species group 61),
Themeda triandra (species group 65) and Eragrostis lehmanniana (species
group 77).
2.3: ARGYROLOBIUM LANCEOLA TUM-ANACAMPSEROS LANCEOLA TA
SHRUBLAND OF THE FALSE UPPER KAROO
The typical habitat of this vegetation unit is steep hillsides. Slopes generally
vary between 150 and 400, where the bedrock consists of dolerite.
Geologically the area is underlain by the Beaufort Series, interrupted by
dolerite layers. 31 Communities were included in this vegetation unit and
are:
* communities derived from the association analysis of the vegetation of
Thaba 'Nchu Mountain (Roberts 1966);
+ communities described by Werger (1973 a) under the Grewio-Rhoetalia
erosae;
* communities described under the Pentzietea incanae (Werger 1973 a);
* communities described under the Rhoetalia ciliato-erosae (Werger 1973 a);
* communities from the Rolfontein Nature Reserve (Jooste 1980); and
* communities encountered in the Soetdoring Nature Reserve.
The differentiating species of this vegetation unit are listed in species
group 8 (Table 11.1). Species with higher than 40% constancy are
Argyrolobium lanceo/atum, Lotononis laxa, 8rachiaria serrata, Hermannia
linearifolia, Phyllanthus maderaspatensis, Helichrysum lucilioides and Sutera
ha/imifolia (species group 8, Table 11. 1).
The diagnostic species are listed in species group 9 (Table 11.1).
Anacampseros /anceo/ata and Pelargonium aridum are the most important
(Table 11.1).
293
Numerous woody species occur. A few conspicuous (constancies higher
than 60 %) species are Euclea crispa subsp. ovata (species group 4),
Hermennie cuneifolia (species group 10), Rhus erosa, Olea europaea,
Diospyros austro-africana (species group 14), Helichrysum dregeanum,
Solanum supinum, Plexipus pinnatifidus, Helichrysum zeyheri, Lightfootia
albens (species group 19), Melolobium microphyllum, Pegolettia retrofracta
(species group 26), Tarchonanthus camphoratus (species group 38),
Gazania krebsiana, Ehretia rigida (species group 53), Felicia muricata, Rhus
ciliata (species group 55), Rhus burchellii (species group 65), Diospyros
Iycioides (species group 71), the Karoo encroacher Chrysocoma ciliata
(species group 76), Protasparagus suaveolens, Walafrida saxatilis (species
group 77) and Pentzia globosa (species group 83).
Some prominent grasses include Sporobolus fimbriatus, Enneapogon
scoparius (species group 55), Tragus koelerioides, Digitaria eriantha (species
group 59), Eustachys paspalOides (species group 60), Heteropogon
contortus, Aristida congesta, A. diffusa (species group 61), Themeda
triandra (species group 65), Eragrostis lehmanniana (species group 77) and
Eragrostis curvula (species group 80).
A few ferns occur and include Cheilanthes hirta (species group 11), C.
eckloniana and Pellaea calomelanos (species group 14).
CLASS 3: ERAGROST/S LEHMANNIANA-CHRYSOCOMA CILIATA
KARRO.D VEGET AT.ON
The Eragrostis lehmanniana-Chrysocoma ciliata karroid vegetation includes:
* Communities derived from the Soetdoring Nature Reserve and adjacent
areas;
* the Hermannio coccocarpae-Nestleretum confertae (Werger 1973 a) along
the Upper Orange River Valley;
* Rhoetalia ciliato-erosae (Werger 1973 al along the Upper Orange River
Valley; and
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* plant communities from the Rolfontein Nature Reserve (Jooste 1980).
The typical habitat consists of koppies and ridges in the Soetdoring
Nature Reserve and in the wide stretch of land from Aliwal North to
Petrusville in the Upper Orange River Valley (Werger 1973 a). The slopes are
gentle and varies between 0° and 9°. It is also found on sites that were
ploughed several years ago and had been left unused since. Badly eroded
areas are common and are recovering slowly. According to Werger (1973
a), this vegetation unit is usually poor in species, and Eragrostis
/ehmanniana scores constantly high cover values. This vegetation type is
transitional between shrubland and grassland and usually occurs on shallow
lithosols.
The vegetation includes 26 karroid shrubby communities occurring on
sloping terrains of the hills. Exclusive diagnostic species are absent from this
vegetation unit which is dominated by graminoids.
Prominent woody and semi-woody species include Rosenia humilis
(species group 15), Hermannia erodioides (species group 21), Gnidia
po/ycepha/a, He/ichrysum asperum, Metotobium microphyllum (species group
26), Gazania krebsiana (species group 54), Fe/icia muricata (species group
55), Hermannia coccocarpa, Geigeria filifolia (species group 60), Selsole
g/abrescens (species group 75), Chrysocoma ei/iata (species group 76),
Protasparagus suaveo/ens (species group 77) i Pentzia g/obosa and Thesium
hystrix (species group 83).
Important grasses include Enneapogon desvauxii (species group 26),
Eragrostis ch/orome/as, Cynodon dacty/on .(species group 41), Tragus
koe/erioides, Digitaria eriantha (species group 59), Heteropogon contortus,
Aristida congesta (species group 61), Themeda triandra (species group 65),
Eragrostis obtusa (species group 76), Eragrostis curvu/a (species group 80),
Fingerhuthia africana (species group 83).
The data suggest that the vegetation is heterogeneous and that a
comprehensive revision of this class is necessary. The ecotone between the
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Grassland and Nama-Karoo Biomes contains many of the mentioned species
and need to be studied in detail.
This class divides into two distinct orders (Table 11.1)
3.1: ROSENIA HUMILIS-DUTHIASTRUM LINIFOLIUM DWARF
SHRUBLAND
The Rosenia humilis-Duthiastrum linifolium dwarf shrubland consists of 17
plant communities and includes:
* communities derived from the Soetdoring Nature Reserve and adjacent
areas;
* the Hermannio coccocarpae-Nestleretum confertae (Werger 1973 a) along
the Upper Orange River Valley; and
* Rhoetalia ciliato-erosae (Werger 1973 a) along the Upper Orange River
Valley.
The typical habitat consists of hills and ridges of the Soetdoring Nature
Reserve and the stretch of land from Aliwal North to Petrusville in the Upper
Orange River Valley (Werger 1973 a). Here the grasslands degrade due to
anthropogenic influences, particularly overgrazing by sheep, resulting in the
floristically poor Hermannio coccocarpae-Nestferetum confertae (Werger
1973 a), typical of the False Upper Karoo. The soils are sandy loams,
usually more than 1 m deep and of the solonetic type (Werger 1973 a).
This vegetation unit is characterized by the species listed in species
group 15 and 16 (Table 11. 1).
Among the ·differentiating species, listed in species group 15, Rosenia
humilis, Conyza bonariensis, the reed Cyperus usitatus and the grass
Sporobofus fudwigii are the most abundant (Table 11. 1).
Species listed in species group 16 are exclusive to this vegetation order
and are Duthiastrum finifolium, Menodora africana, Kyllinga alata, Brachiaria
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serrata, Gethyllis undu/ata, Moraea po/ystachya and Oenothera tetraptera
(Table 11.1).
Strong affinities between this vegetation unit and the Argyr%bium
/anceo/atum-Anacampseros /anceo/ata Order of the Rhus erose-Otee
europaea Class exist and are clearly illustrated in species groups 17, 18 and
19 (Table 11.1).
Other prominent woody and semi-woody species included in this
vegetation order are So/anum supinum (species group 19), Metotobium
microphyllum (species group 26), /ndigotera a/ternans (species group 27),
Hermannia comosa (species group 47), Pterothrix spineseens (species group
53), Gazania krebsiana (species group 54), Fe/icia muricata (species group
55) I Hermannia coccocarpa, Geiqerie tilttotie, Nenax microphy/la (species
group 60), Nidore/la reseditolia (species group 69) and Chrysocoma ei/iata
(species group 76).
The most important grasses are Sporobelus /udwjgJÏ, Digitaria
argyrograpta, Erioch/oa parvispicu/ata (species group 15) I Enneapogon
desvauxii (species group 26) I Eragrostis ch/orome/as (species group 41) I
Cymbopogon pturinoais (species group 47), Eragrostis superbe, Enneapogon
scoparius (species group 55), Oropetium capense (species group 56),
Tragus koe/erioides, Digitaria eriantha (species group 59), Heteropogon
contortus, Aristide congesta, A. diffusa (species group 61), Themeda
triandra (species group 65), Eragrostis obtusa (species group 76); E.
/ehmanniana (species group 77), Eragrostis curvu/a (species group 80) and
Panicum cotoretum (species group 84).
The presence and abundance of Themeda triandra (species group 65)
and Eragrostis curvu/a (species group 80) in this association on sites that
have been withdrawn from grazing for some time, support the suggestion of
Werger (1973 a) that these species are relicts of a former grassland
vegetation in these areas (Du Preez 1991).
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3.2: HERMANNIA ERODIOIDES-SYNCARPHA ARGYROPSIS DWARF
SHRUBLAND OF THE ROLFONTEIN NATURE RESERVE
The Hermannia erodioides-Syncarpha argyropsis dwarf shrubland of the
Rolfontein Nature Reserve near the Vanderkloof Dam includes nine
communities and is situated on the pediplains between the mesas (Jooste
1980).
Species from species group 21 differentiate this order. Hermannia
erodioides, Salvia disermas, Sa/so/a cal/una and the grass Stipagrostis
unip/umis are the most important (Table 11.1). This vegetation unit is
distinguished from all other vegetation units by the presence of Syncarpha
argyropsis (species group 22). Affinities with the Argyr%bium /anceo/atum-
Anacampseros /anceo/ata Order are illustrated by the presence of species
from species group 21 (Table 11.1).
Woody and semi-woody species often encountered are Gnidia
po/ycepha/a, He/ichrysum asperum (species group 26), Hermannia vestita
(species group 55), H. coccocerpe (species group 60), Rhus burchellii
(species group 65), Lycium hirsutum (species group 70), Chrysocoma ei/iata
(species group 76), Protasparagus suaveo/ens (species group 77) and
Pentzia g/obosa (species group 83).
Important grasses frequently encountered include Enneapogon desvauxii
(species group 26), Cynodon' dacty/on (species group 41), Tragus
koe/erioides (species group 59), Heteropdgon contortus, Aristida congesta
(species group 61), Themeda triendrs (species group 65), Eragrostis obtusa
(species group 76), E. tehmenniene (species group 77), E. curvu/a, Ch/oris
virgata (species group 80) and Fingerhuthia africana (species group 83).
A comprehensive formal syntaxonomical review of these syntaxa is
needed.
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CLASS 4: PHAEOPTILUM SPINOSUM-ZYGOPHYLLUM GILFILLANII
SHRUB AND DWARF SHRUB COMMUNITIES OF THE ROCKY SOILS OF
THE WESTERN UPPER ORANGE RIVER VALLEY
This shrubland includes:
* The syntaxa described by Werger (1973 a) under the class Pentzietea
incanae and the order Stipagrostion.
The typical habitat consists of a flat monotonous landscape, west of
Petrusville in the western Upper Orange River Valley. The substrata are
formed by Ecca and Dwyka deposits and, in the westernmost section of the
Upper Orange River, by Ventersdorp lavas. Soils are usually lithosols or of a
sandy loam type except in some localities north of the river and in lees
south of the river where thick deposits of Kalahari sand have accumulated.
These habitats characteristically bear a vegetation dominated by Stipagrostis
spp. Because of severe overgrazing for just over a century the dominance of
Stipagrostis spp. have locally given way to an abundant growth of
Rhigozum trienoiomum in particular (Werger 1973 a).
Species listed in species groups 23 and 24 differentiate this class (Table
11 .1). Phaeopti/um spinosurn, Dicoma macrocepha/a, P/inthus kerooicus,
Schizog/ossum capitatum, the grass Eragrostis porose, Pentzia ca/carea,
Peliostomum /eucorrhizum, Aatosimum spineseens. P/inthus crvptocerpus,
Hermannia spinosa and MonechriJa incanum (species group 23) are the
most important among the differentiating species. Species exclusive to this
class are listed in species group 24 and are Nol/etia arenosa, Zygophyl/um
gilfillanii, Aptosimum a/bomarginatum, Euphorbia aequoris, Coe/achyrum
yemenicum, Hoodia gordonii and Rhynchopsidium pumi/um.
Important dicotyledons frequently encountered include Gnidia
po/ycepha/a, Aptosimum mar/othii, Lessertia pauciflora, Kyphocarpa
angustito/ia, Eriocepha/us pubescens, Po/ygala leptophylla (species group
26), Indigofera a/ternans (species group 27), the thorn tree Acacia mellifera
(species group 38), Gazania krebsiana (species group 54), Eber/anzia
spinosa (species group 56), Geigeria ti/ito/ia (species group 60), Salso/a
299
glabrescens (species group 75), Chrysocoma ci/iata, Protasparagus laricinus
(species group 76), P. suaveolens (species group 77), Lycium pilifolium
(species group 81), Eriocephalus spineseens (species group 82), 8arleria
rigida, Pentzie incana, Thesium hystrix and Rhigozum trichotomum (species
group 83).
Important grasses are Enneapogon desvauxii, Aristida adscensionis
(species group 26), Tragus koelertoides (species group 59), Aristida
congesta (species group 61), Tragus berteronianus, Eragrostis obtusa
(species group 76), E. lehmanniana '(species group 77), Fingerhuthia
africana, Stipagrostis ciliata and Stipagrostis obtusa (species group 83,
Table 11.1).
The data suggest that the vegetation is heterogeneous and that a
comprehensive revision of this class is necessary.
CLASS 5: ACACIA KARROO HEBENSTRETIA INTEGRIFOLIA
SHRUBLAND OF THE RIVER BANKS AND FlOODPLAINS
Ten Plant communities included in this class are the following:
* Diospyrion Iycioidis (Werger 1973 a) along the entire Upper Orange River;
* Acacia karroo-Celtis africana Community described by Werger (1973 bl
from the Tussen die Riviere Game Farm;
* Selix mucronata Community 'from the islands in the Modder River
(Rossouw 1983); and
* Acacia karroo Communities from the banks of the Modder River, along dry
rivulets, on flat plains and floodslopes and on mechanically disturbed,
overgrazed and trampled areas in' the Bloemfontein area (Rossouw 1983).
The habitat conditions associated with this vegetation unit are the same
as in the Acacia karroo riparian thicket, described by Du Preez (1991).
According to Werger (1973 a) true vascular waterplant communities are
virtually absent from the Orange River, probably due to the high silt load of
the water, although the large, sudden floods of this river might also be an
300
important factor in this respect (Butcher 1933, Edwards 1969). The special
adaptation of these vascular waterplants to their habitat, which is subject to
flooding, silting and alternating dry and wet conditions, is discussed by
Ambasht ("1968) in a paper on a tlorlsticallv similar community on the banks
of the Ganges.
This class is characterized by species groups 28 and 29 (Table 11.1).
The most important differentiating species are the grasses Melica
decumbens, Setaria verticil/ata, Bromus catharticus, Lepidiurn africanum and
Urochloa penicokies (species group 28). Differentiating woody and semi-
woody species are Rhus pyroides subsp. pyroides, Protasparagus cooped
(species group 28).
Other differentiating species include Antizoma angustifolia, Bidens
bipinnata, Pentarrhinum insipidum, Solanum retrottexum, Sonchus
oleraceus, Delosperma cooperi, Silene undulata, Opuntia vulgaris, Rubia
petioleris, Protasparagus setaceus and the small forb Alternanthera pungens
(species group 28).
The diagnostic species exclusive to this class are the species listed in
species group 29 and include Chenopodium murale, Hebenstretia integrifolia,
Rubia horrida and Verbena officinalis (Table 11.1).
Other woody and semi-woody species of importance are Ziziphus
mucronata (species group 54), Felicia muricata (species group 55), Acacia
karroo (species group 64), Atriplex semibaccata (species group 69), Lycium
hirsutum (species group 70), Diospyros Iycioides (species group 71),
Protasparagus laricinus . (species group 76), P.· suaveolens (species group
77), Lycium cinereum and the karroid Pentzia globosa (species group 83).
In the lower stratum Sporobotus fimbriatus (species group 55) and
Eragrostis curvula (species group 80.) tend to dominate (Table 11.1).
Similar Acacia karroo communities, representative of this class, have
been described outside the study area, especially in the Bankenveld (Acocks
'----------~---------------- ._ J
301
1988) and the western Transvaal Cymbopogon- Themeda Veld (Acocks
1988). Examples are communities described by Bredenkamp et al. (1989)
from the Potchefstroom area, Bredenkamp & Bezuidenhout (1990) from the
Faan Meintjes Nature Reserve, Bezuidenhout & Bredenkamp (1990) from the
western Transvaal dolomitic area, Du Preez & Venter (1990) from the
Vredefort Dome area and Kooij et al. (1990 a, b, c) from the north-western
Free State.
CLASS 6: ACACIA MELLIF_ERA-TARCHONANTHUS CAMPHORATUS
SHRUBLAND OF THE ROCKY OUTCROPS
This woodland includes:
* Acacia communities desertbed by Malan (1992);
* Acacia karroo Community described by Rossouw (1983);
* communities derived from relevés in the Bloemfontein area and the
southern Free State; and
* communities described by Jooste (1980).
The typical habitat consists of relatively dry hills, ridges and slopes,
mainly west of the 500-600 mm per annum rainfall interval. Communities
described by Jooste (1980) are associated with rocky habitat in which 60%
of the surface is covered with roundish and sub-angular stones of between
0.3 and 0.7 m in diameter while the vegetation in the Jacobsdal area
includes multistratal shrubby communities on Kalahari sand.
Conspicuous woody' species associated with this class are Acacia tortilis
(species group 33), A. mel/ifera, Tarchonanthus camphoratus (species group
38), Ehretia rigida (species group 54), the Karoo encroacher Chrysocoma
ciliata (species group 76), Protasparagus suaveolens (species group 77) and
the karroid shrublet Pentzia globosa (species group 83).
Prominent grasses include Heteropogon contortus, Aristida congesta, A.
diffusa (species group 61), Themeda triandra (species group 65), Eragrostis
curvula (species group 80) and Fingerhuthia africana (species group 83).
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The Acacia mel/ifera- Tarchonanthus camphoratus shrubland of the rocky
outcrops divides into two distinct vegetation units (Table 11.1).
6.1: ACACIA TORTILIS-ACACIA HEBECLADA SHRUBlAND OF THE
LOW-LYING ROCKY OUTCROPS
This thorny shrubland order is primarily associated with the relatively low-
lying woodland vegetation at the footslopes and protected areas of the
Rolfontein Nature Reserve near the Vanderkloof Dam. Twenty-one
communities were included and are:
* Acacia communities in the Rolfontein Nature Reserve; and
* Additional relevés encountered in the region between the Gariep and
Vanderkloof Dams by the present author.
This area nearly always consists of dolerite slopes, sometimes
interrupted by layers of Beaufort or Ecca sandstones, mudstones or shales
covered by a shallow lithosol, which contain a large amount of gravel
(Werger 1973 a). Surface rocks are predominantly doleritic.
The differentiating species of this thorny shrubland are listed in species
group 33. Acacia torti/is is the only dominant species. Exclusive to this
vegetation unit are the species listed in species group 34. Acacia hebeclada,
Heliophi/a carnosa and Hermannia modesta are unique to this order (Table
11.1). Other frequently occurring species include the thorn tree Acacia
mel/ifera, Tarchonanthus camphoratus (species group 38), the shrub Ehretia
rigida (species group 54), the Karoo encroacher Chrysocoma ciliata (species
group 76), Protasparagus suaveolens (species group 77), and karroid dwarf
shrub Pentzia globosa (species group 83, Table 11.1).
Important grasses include Cenchrus cilieris (species group 38),
Enneapogon scoparius (species group 55), Heteropogon contortus, Aristida
diffusa (species group 61), Eragrostis curvula (species group 80) and
Fingerhuthia africana (species group 83).
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6.2: PHYLLANTHUS PARVULUS-ABUT/LON PYCNODON SHRUBLAND
OF THE HIGHER LVING AREAS
This shrubland is situated on higher-lying areas on the slopes and plateaux
of dolerite hills in the region of the Vanderkloof Dam. Dolerite hills covered
by shallow lithosols occur. Twenty-one communities encountered were
included.
The differentiating species are poorly developed and are listed in species
group 36 (Table 11.1). Abutilon pycnodon, Cullen obtusifolia and Justicia
protracta (species group 37) are the only diagnostic species characterizing
this vegetation unit (Table 11.1).
Prominent woody and semi-woody species with constancies of 60% and
higher, occasionally associated with this order include the thorn tree Acacia
mellifera, the shrubs Tarchonanthus camphoratus (species group 38), and
Ehretia rigida (species group 54), the Karoo encroacher Chrysocoma ciliata
(species group 76) and the shrub Protasparagus suaveolens (species group
77).
Grasses include Digitaria eriantha (species group 59), Heteropogon
contortus, Aristida diffusa (species group 61), Themeda triandra (species
group 65), Eragrostis lehmanniana (species group 77) and Fingerhuthia
africana (species group 83).
CLASS 7: AR/ST/DA B/PARTlTA - LACTUCA SERR/OLA MOIST
GRASSLAND OF THABA 'NCHU
Plant communities included in this class are derived from the association
analysis of 12 grassland communities of Thaba 'Nchu Mountain area,
approximately 60 km east of Bloemfontein (Roberts 1966).
304
This moist grassland vegetation occurs east of the 500 mm rainfall
isohyet with the largest part falling within the 600-800 mm rainfall interval
(See Chapter 2).
The Aristida bipartita-Lactuca serrio/a moist grassland of the eastern
plains is characterized by Lactuca serrio/a (species group 40) that
distinguishes this class from all the other classes in the study area:
The vegetation is mostly dominated by grasses with trees and shrubs
less conspicuous. The most prominent grasses are Aristida bipartita (species
group 39), Eragrostis ch/orome/as, Cynodon dacty/on (species group 41),
Eragrostis plana, Trichoneura grandig/umis, Eragrostis gummiflua,
Microchloa caffra (species group 44), Cymbopogon pturlnodis, E/ionurus
motleus (species group 47), Setaria sphace/ata (species group 55), Tragus
koe/erioides (species group 59), Heteropogon contortus, Aristida congesta
(species group 61), Themeda triandra (species group 65), Eragrostis obtusa,
Tragus berteronianus (species group 76), Ch/oris virgata (species group 80)
and Aristida eaneseens (species group 81).
" The presence of species such as the forbs Berkheya onopordifolia
(species group "76) and B. pinnatifida (species group 77) and grasses such
as Aristida bipartita, Eragrostis eh/orome/as, Cynodon dacty/on, Eragrostis
gummif!ua, E/ionurus mu ticus, Tragus koe/erioides, Aristida congesta,
Eragrostis obtusa, Tragus berteronianus, Ch/oris virgata, Aristida eenesaens
is normally indicative of overgrazed and retrogressed vegetation (See Van
Oudtshoorn 1991 & Fuls 1993).
This class is in accordance with the Themeda triandra-Eragrostis plana
moist grasslands of the eastern plains, described by Du Preez (1991) where
Themeda triandra is dominant, but due" to overgrazing, the vegetation
deteriorated to variations where E/ionurus mu ticus, Aristida junciformis,
Eragrostis eh/orome/as and E. plana dominate (Du Preez 1991).
Diospyros /ycioides (species group 71) is inconspicuous, but virtually the
only shrub species present, with Lycium cinereum and Pentzia g/obosa
(species group 83) the only abundant dwarf shrubs.
305
CLASS 8: ERAGROSTIS PLANA-CYMBOPOGON DIETERLENII MOIST
GRASSLANDS OF THE EASTERN PLAINS
This vegetation class occurs south-east of the Themeda triendrs-
Cymbopogon plurinodis dry grassland plains at a higher altitude and with a
higher rainfall, described by Werger & Coetzee (1978) as Moist Temperate
grassland.
Plant communities in this class are the following:
* the 8rachiaria serrata-Elionurus muticus;
* Eragrostis plana-E. gummiflua; and
* Pentzie globosa-Eragrostis curvula communities described by Werger
(1973 a) from the eastern Upper Orange River Valley; and
* communities derived from relevés encountered on Molteno sandstone on
the Aasvoëlberg Mountain near Zastron in the southern Free State.
The 8rachiaria serrata-Elionurus muticus Community occurs on sites
mainly in the area covered by the sandy Cymbopogon- Themeda Veld
(Acocks 1953), which are not too severely overgrazed and trampled. The
soils are deep pseudopodzolic soils with a slightly acid topsoil of loamy sand
on nearly horizontal layers of Molteno sandstone (Werger 1973 a).
The Eragrostis plana-Eragrostis gummif!ua Community is encountered on
damp sites with a deep soil of loamy sand on gentle slopes and plains of
Molteno sandstone, upstream from Aliwal North (Werger 1973 a).
The Pentzie globosa-Eragrostis curvula Community occurs in the vicinity
of Aliwal North, where the False Upper Karoo merges into the grassland
vegetation. The soils are acid loamy sands and sandy loams on level to
slightly sloping Molteno and Beaufort sandstones (Werger 1973 a).
According to Scheepers (1975) variation· in vegetation is mostly
determined by geology, position in the landscape and biotic factors,
306
especially grazing. In this region the rainfall exceeds 600 mm/a and falls
within the 600-800 mm rainfall interval (Chapter 2). This high rainfall tends
to smooth out the variations in the physical factors of the environment, so
that gradual transitions in the vegetation become the rule and abrupt
discontinuities the exception (Du Preez 1991). According to Acocks (1988)
these areas are too dry and/or too frosty for the development of any kind of
forest. Shrubs are restricted to the rocky hills and mountains. Daubenmire
(1968) stated that fire is the most important factor in preventing the
development of woody vegetation in this type of area.
This class is distinguished from all the other classes by the presence of
species listed in species group 43 (Table 11.1). The diagnostic species are
the perennial, tufted grass Cymbopogon dieterlenii, Ficinia sp., Hermannia
genicu/ata and the forb Se/ago ga/pinii (Table 11.1). Species differentiating
this grassland are listed in species group 42 (Table 11.1). Strong affinities
with the Aristida bipertite-Lectuce serrio/a moist grassland of Thaba 'Nchu
are shown in species group 44 (Table 11.1). The grasses Eragrostis plana,
Trichoneura grandig/umis, Eragrostis gummiflua and Microchloa caffra show
the strongest affinities between the two classes. The grasses Eragrostis
ch/orome/as (species group 41), Tragus koe/erioides (species group 59) and
Eragrostis obtusa (species group 76) have lower presences here as in the
Aristida bipartita-Lactuca serrio/a moist grassland of Thaba 'Nchu. The
absence of Cynodon dectvion (species group 41), Ch/oris virgata (species
group 80) and Panicum cotoretum (species group 84) in this grassland. is
also noteworthy. Grasses with higher frequencies in this moist grassland
include Eragrostis capensis (species group 44), Elionurus muticus (species
group 47), Sporobo/us fimbriatus (species group 55), Digitaria eriantha
(species group 59), Heteropogon contortus (species group 61) and
Eragrostis curvu/a (species group 80) .
Prominent woody species are Rhus erosa (species group 14) and the
karroid shrub Felicia filifolia (species group 55).
The most abundant grasses include Eragrostis racemosus, Panicum
stapfianum (species group 42), Eragrostis plana, Trichoneura grandig/umis,
Eragrostis gummiflua, Microchloa caffra, Eragrostis espensis (species group
307
44), Cymbopogon plurinodis, £/ionurus muticus (species group 47), Setaria
sphacelata, Sporobolus fimbriatus (species group 55), Digitaria eriantha
(species group 59), Heteropogon contortus, Aristida congesta (species
group 61),· Themede triandra (species group 65), Eragrostis obtusa (species
group 76), E. lehmanniana (species group 77), Eragrostis curvu/a (species
group 80) and Fingerhuthia africana (species group 83).
The most prominent forbs are Berkheya discotor (species group 42),
Gezenie krebsiana (species group 54) and Walafrida saxatilis {species group
77).
Some of the association analysis end groups of Roberts' study of Thaba
'Nchu (1966), particularly end group 4, show strong floristic affinities with
the Brachian"a serrete-Hionurus muticus Community and it is possible that
the same community occurs in the Upper Orange River Valley and at Thaba
'Nchu (Werger 1973 a).
A comprehensive formal syntaxonomical review of these syntaxa
including communities from outside the study area, is needed.
CLASS 9: THEMEDA TRIANDRA-CYMBOPOGON PLURINODIS
GRASSLANOS OF THE WESTERN PLAINS
The vegetation of the Grassland Biome follows a rainfall gradient which
generally corresponds to the relative contributions to the plant cover by
"sweet" and "sour" grasses (Rutherford & Westfall 1994). "Sweet" grasses,
in contrast to "sour" grasses, usually have a lower fibre content, maintain a
higher above-ground nutrient level into winter and tend to be more palatable
to stock. "Sweet" grasses (e.g. Panicum coloratum) are more common in
areas with a mean annual rainfall below 625 mm, whilé sour grasses (e.g.
Aristida junciformis) tend to dominate in areas with a mean annual rainfall of
above 625 mm (Rutherford & Westfall 1994). The border between moist
and dry grassland is best expressed as ranging between the 500 and 700
mm isohyet (Rutherford & Westfall 1994).
308
This class is encountered to the east of the 600 mm rainfall isohyet in
the southern Free State and is dominated by Themeda triandra, Digitaria
eriantha and Eragrostis lehmanniana. Grasslands with Themeda triandra
occur widespread over Africa (Lebrun 1947; Volk & Leippert 1971). The
Themedetalia triandrae described by Lebrun (1947) for East Africa are,
however, absent in South Africa. It therefore seems that the southern
African Themeda triandra communities do not belong to this order (Du Preez
1991). This class is in accordance with the Aristida junciformis-Eragrostis
plana Grassland described by Fuls (1993), where Themeda triandra and
Eragrostis curvula dominate. According to Werger (1973 a) the presence
and abundance of Themeda triandra and Eragrostis curvula on sites that
have been withdrawn from grazing for some time suggests that these
species are relics of a former gr.assland vegetation. The development of
woody vegetation is probably prevented by regular frosts (Acocks 1988,
Werger 1973 a) and fire (Walter 1973, Scott 1970).
The topography is tlat to undulating with isolated hills and ridges
occurring occasionally. The soils of the moist grasslands are usually more
leached by the higher rainfall and tend to be dystrophic in comparison with
the generally eutrophic soils of the dry grasslands (Rutherford & Westfall
1994). The area in which this class occurs is mainly underlain by the
Beaufort and Ecca Groups.
According to Acocks (1988) the grasslands of the Upper Orange River
Valley merge into False Karoo vegetation towards the drier west and south.
This is mainly due to anthropogenic influences, particularly overgrazing by
sheep (Du Preez 1991).
Thirty-eight Plant communities are included in this class and are derived
from relevés in the Bloemfontein West District (Malan 1992), the Upper
Orange River Valley (Werger 1973 a) and additional relevés compiled in the
southern Free State by the present author.
This grassland is characterized by the diagnostic species listed in species
group 46 (Table 11.1) and are Arctotis arctotoides, Dipcadi glaucum,
Hypoxis filiformis and Tragopogon dubius.
309
Trees and shrubs are virtually absent and the vegetation is dominated by
grasses. Grasses with constancies of 60% and higher include Cymbopogon
plurinodis (species group 47), Digitaria eriantha (species group 59), Aristida
congesta (species group 61), Themeda triandra (species group 65),
Eragrostis obtusa (species group 76), Eragrostis lehmanniana (species group
77), Eragrostis curvula (species group 80) and Fingerhuthia africana (species
group 83).
The presence of the Karoo encroacher Chrysocoma ciliata (species group
76) is a clear indication of veld deterioration.
CLASS 10: HERTlA PALLENS-PROSOPIS VELUTINA KARROID
VEGETATION OF THE DRY WESTERN FREE STATE
The Hertia pallens-Prosopis velutina karroid vegetation of the dry western
Free State is encountered to the west of the 600 mm rainfall isohyet. This
area includes the ecotone between the Grassland and Nama-Karoo Biomes.
This class comprises 61 plant communities and includes:
.. relevés encountered in the Bloemfontein West District (Malan 1992);
.. communities of generally limited spatial extent (minor communities) in the
Upper Orange River Valley (Werger 1973 a); and
.. additional relevés compiled in the southern Free State by the present
author.
According to Werger (1973 a) the grasslands of the Upper Orange River
Valley are classified into three distinct plant communities, without any
syntaxonomical rank. Towards the drier west and south the grassJands
merge into False Upper Karoo vegetation (Acocks 1988). Here the
grassJandsdegrade due to anthropogenic influences, particularly overgrazing
by sheep, resulting in the floristically poor Hermannio coccocarpae-
Nestleretum confertae (Werger 1973 a), typical of the False ·Upper Karoo.
The vegetation of this class is characterized by species groups 49 and 50,
all with low constancies (Table 11.1). Species exclusive to this class are
L- __
310
listed in species group 49 and include the exotic tree Prosopis velutina.
Associated diagnostic dwarf shrubs and forbs include Amaranthus
thunbergii, Deverra denudata, Galenia africana, Geigeria ornativa, Hertia
ei/iata, Psilocau/on junceum, Pteronia incana, Ruschia rigida, Staehys
hyssopoides, Suaeda fruticosa, Zygophyllum macrocarpon and Z.
mierophyllum. Eragrostis bergiana is the only diagnostic grass (species
group 49, Table 11.1).
Shrubs and dwarf shrubs with constancies of 40% and higher include
Hertia pallens (species group 48), Eriocephalus erieoides (species group 50),
Felicia muricata (species group 55), Mel%bium candieans (species group
62), Sa/sola g/abrescens (species group 75), Chrysocoma ciliata (species
group 76), Protasparagus suaveo/ens, Wa/afrida saxatilis (species group 77),
Eriocepha/us spineseens (species group 82), Lycium cinereum, Pentzia
globosa, P. incana and Lyeium norridum (species group 83).
Grasses present include Aristida congesta, A. diffusa (species group 61),
Eragrostis /ehmanniana (species grou·p 77), E. curvu/a (species group 80)
and Fingerhuthia africana (species group 83, Table 11.1).
Digitaria eriantha (species group 59) and Themeda triandra (species
group 65) have much lower constancies here as in .the Themeda trienare-
Cymbopogon p/urinodis grassland of the western plains. This is probably
due to habitat disturbance accompanied with lower rainfall in the western
part of the study area.
CLASS 11: OROPETlUM CAPENSE-ANACAMPSEROS FILAMENTOSA
COMMUNITIES ON VERY SHALLOW SOILS ON DOLERITE OUTCROPS
The vegetation of this class was encountered on exposed sheets of rock
and sandstone of a dolerite sill in the Bloemfontein-area. These very
restricted communities occur on dolerite and sandstone rock sheets on the
high-lying areas as well as shallow depressions of dolerite rock sheets on
the plateaux. This class is in accordance with the Orepettam capense
Cornrnunltv on rocky sheets along the slopes and on the plateaux of dolerite
311
hills and ridges in the Willem Pretorius Game Reserve described by Muller
(1986). Seven communities were included.
This class is distinguished by the species listed in species groups 56 and
57 (Table 11.1). Species with frequencies of 60% and higher are the
grasses Oropetium capense, Eragrostis nindensis, the succulents Eberlanzia
spinose, Euphorbia mauritanica, Senecio radicans, Anacampseros truncata,
Chasmatophyllum musculinum, Crassula nudicaulis and Sarcostemma
viminale (species group 56).
Species exclusive to this class are Anacampseros filamentosa,
Stomatium mustellinum, Crassula. corallina, Anacampseros ustulata,
Trachyandra saltii, Otholobium prodiens and Neohenricia sibbettii (species
group 57, Table 11.1).
Other species of importance .include the sedges Mariscus capensis
(species group 58), Cyperus rupestris (species group 66), the grass Aristida
diffusa (species group 61), the thorny shrub Eriocephalus spineseens
(species group 82) and the small fern Cheilarithes eckloniana (species group
14, Table 11.1).
CLASS 12: PHRAGM/TES AUSTRAL/S-SAL/X BABYLON/CA RIPARIAN
VEGETATION
The vegetation of this class is restricted to the poorly-drained flood plains
and dry watercourses of the southern Free State. The habitat is fairly
unstable, due to seasonal flooding and drying which, together with frequent
overqrazinq. have caused the advanced state of degradation of the
vegetation. In some cases this vegetation is dominated by Acacia karroo on
calcareous-sandy soil and also occurs away from river banks on clayey soils
in drainage channels. The soils of the lowlands generally have a higher clay
content than those of the upland areas.
This vegetation unit includes communities derived from:
* relevés in the Bloemfontein area (Malan 1992);
~--------------------------------------------------------------------------
312
* Acacia communities in the Bloemfontein area (Rossouw 1983); and
* additional relevés encountered in the southern Free State by the present
author.
Bezuidenhout (1993) described associated syntaxa with virtually the
same habitat conditions in the western Transvaal grasslands under the
Eragrostido p/anae-Hyparrhenietea hirtae, while Fuls (1993) described the
Cyperus fastigiatus-Hemarthria a/tissima wetland with similar habitat
conditions. Du Preez (1991) refers to it as the Hemarthria a/tissima marsh
and stream bank community.
This class is distinguished by the presence of species occurring in
species groups 62 and 63 (Table 11.1). The differentiating species are listed
in species group 62. The reed Phragmites austra/is, the tree Sa/ix
mucronata, the forbs Rumex lanceolatus and Verbena bonariensis and the
sedge Cyperus longus (species group 62) all have high constancies.
Species exclusive to this class are the naturalized exotic tree Salix
babyIonica, the perennial rhizomatous grass Hemarthria altissima and the
forbs Conium chaerophylloides, Datura ferox, Mentha longifolia and
Po/ygonum kitaibe/ianum (species group 63, Table 11.1).
Also prominent are the trees Acacia karroo (species group 64), Diospyros
Iycioides (species group 71), the shrub Protsspereaus laricinus and the forbs
Tagetes minuta and Tribulus terrestris (species group 76).
Typha capensis, normally associated with wetlands (Eckhardt et al.
1993), Juncus exsertus (species group 68), Xanthium strumarium and
Rumex crispus (species group 78) are among the other species normally
associated with wetlands.
A comprehensive formal syntaxonomical review of these syntaxa
including the communities from out~ide the study area, is needed.
313
CLASS 13: MARISCUS CONGES TUS-PERSICA RIA SERRULATA
STREAM RIPARIAN VEGETATION
Plant communities included in this vegetation unit are:
* wetland communities derived from relevés in the Bloemfontein area (Malan
1992); and
* communities derived from relevés in the southern Free State and
Soetdoring Nature Reserve.
This vegetation unit occurs on the banks of perennial rivers and streams
characterized by relatively strongly flowing water.
Mariscus congestus, Cyperus rupestris, Medicago sativa, Agrostis
lachnantha and Juncus rigidus are the .most important among the
differentiating species (species group 66, Table 11.1).
The diagnostic species are listed in species group 67. Persicaria serrulata
and Cichorium intybus the most abundant.
Cvperus longus (species group 62), Tvohe capensis (species group 68),
Nidorella reseditolie (species group 69) are also abundant. Diospyros
Iycioides (species group 71) is the only prominent tree present. Asclepias
fruticosa (species group 76) is especially abundant along drainage channels
with clayish soil.
Grass species are scarce and only Cynodon incompletus, Miscanthus
espensis (species group '62), Agrostis lachnantha, (species group 66),
Panicum maximum (species group 70), Hyparrhenia hirta (species group 71)
are present.
Related vegetation types outside the study area were described by Kooij
et al. (1991), Bezuidenhout (1993), Fuls (1993) and Eckhardt et al. (1993).
314
CLASS 14: JUNCUS KRAUSSII-PHRAGMITES MAURITIANUS
WETLAND AND PAN VEGETATION
This is a transitional vegetation unit, representing the peripheral zone of the
pans where the vegetation of the drier surrounding communities and those
find within the pans coincide (Eckhardt et al. 1993). Similar habitat
conditions as in the Senecio inaequidens-Cynodon transvaalensis Pan
Community (Eckhardt et al. 1993) were encountered. 10 Communities
encountered in the dry western Free State are included.
The vegetation is characterized by species groups 72 and 73 (Table
11.1). Species exclusive in this class are aquatic plants such as Phragmites
mauritianus, Sclrpus dioicus, Cyperus laevigatus, Cyperus sp. and the small
perennial grass Sporobolus tenellus (species group 73).
Lobelia thermalis, Cirsium vu/gare, Wahlenbergia androsacea and Scirous
dioecus (species group 72) are the most important species differentiating
this vegetation unit.
This class is dominated by Lobelia thermslis. Cirsium vu/gare (species
group 72), Juncus kraussii (species group 74) and Cyperus marginatus
(species group 75).
Grasses are scarce and only Sporobolus tenellus (species group 73),
Eragrostis obtusa, Tragus berteronianus (species group 76), E. lehmanniana
(species group 77) and Fingerhuthia africana (species group 83) are
important.
CLASS 15: DIPLACHNE FUSCA SETARIA INCRASSATA PAN
VEGETATION
This class is associated with the central zones of pans and agrees with the
Chloris virgata--Eragrostis bieolor tall closed grassland associated with poorly
drained, moderately deep, clayey soils (> 25% clay content, A - & B-
horizons), described by Bezuidenhout (1995). Similar communities were
315
described by Eckhardt et al. (1993) under the Dip/achne fusca-Cynodon
transvaa/ensis Pan Community and Fuls (1993) under the Sporobo/us
ioc/ados-Diplachne fusca PanVegetation.
The only diagnostic species is the perennial, stoloniferous, mat-forming
swamp grass Diplachne fusca (species group 79). D. fusca appears to be
annual, "dlsappearlnq" during the dry season or prelonged dry spells, only to
reappear within a week or so after substantial rain (Fuls 1993).
Woody and semi-woody species are absent and only a few grasses and
forbs occur. The most important grasses are Setaria incrassata (species
group 78), Eragrostis curvula and Ch/oris virgata (species group 80). Sutera
a/bit/ora (species group 13) is the most important forb (Table 11.1).
Xanthium strumarium, Rumex crispus, Hibiscus trionum, Sa/via
verbenaca and Schkuhria pinnata (species group 78), also associated with
overgrazed areas (Fuls 1993), are the most important differentiating species
present (Table 11.1).
CLASS 16: FINGERHUTHIA AFRICANA-HELICHRYSUM PENTZIOIDES
PAN GRASSLAND
This class is encountered in dried out pans in the central parts of the study
area and includes only, two communities.
No exclusive character species occur, but the vegetation is differentiated
by the species listed in species group 81, all of which have constancies of
60% and higher.
Forbs are scarce with Helichrysum pentzioides (species group 81) the
most abundant. The only abundant grasses are Enneepoqon scoparius
(species group 55), Aristida canescens, Sporobolus ioc/ados (species group
81), Fingerhuthia africana, Stipagrostis ciliata and S. obtusa (species group
83).
316
Lycium pilttolturn (species group 81), L. cinereum and L. horridum
(species group 83) are the most important shrubs. Karoo bushes like the
thorny Eriocephalus spineseens (species group 82), Pentzia incana, P.
globosa and Thesium hystrix (species group 83) also occur (Table 11.1).
ORDINATION
Three hundred ninety-four synrelevés were used in an ordination algorithm,
namely Detrended Correspondence Analysis (DECORANA, Hill 1979 b). This
was done in order to determine possible vegetation and associated
environmental gradients, as well as floristic relationships among the
transitions between the communities. In the scatter diagrams (Figures 11.1-
11.3) the distribution of the major syntaxa along the first and second axes
of the ordinations .are given.
Figure 11.1 shows the scatter diagram of the whole data set. The
distribution of the major syntaxa along the first and second axes of the
erdination is given.
Along the first axis the plant communities associated with deep soils are
to the left of the diagram, while the syntaxa primarily associated with rock
sheets are to the right. Pan vegetation is situated to the top with wetland
vegetation to the bottom of the diagram (Axis 2, Figure 11.1).
Figure 11.2 shows a DECORANA ordination of all the major syntaxa
included in figure 11.1, except the communities associated with very
shallow soils on rock slabs (indicated by k in Figure 11.1). In the scatter
diagram the distribution of the syntaxa along the first and second axes of
the DECORANA ordination is given (Figure 11.2). Although no distinct
discontinuity can be observed, the plant communities are restricted to
specific spatial areas in the diagram. Along the first axis the syntaxa
associated with deep sandy soils are situated to the left of the diagram, the
plant communities in rocky habitat to the middle and the syntaxa associated
with clayish soils to the right of the diagram. The second axis illustrates a
317
habitat gradient. Pan vegetation of the western Free State are to the top of
the diagram with the wetland communities to the bottom (Figure 11.2).
Figure 11.3 shows a scatter diagram of the distribution of the major
syntaxa along the first and second axes of the DECORANA ordination. In
this diagram all the wetland communities and the communities associated
with rock slabs are excluded (indicated by m, n, j and k in Figures 11.1 &
11.2). The distribution of the major syntaxa indicates a distinct discontinuity
among some of the plant units. The first axis illustrates a gradient of rainfall.
Ptant communities to the teft of the diagram are mainly karroid vegetation
associated with low rainfall regions (300 mm per annum and less),
especially in the dry western parts of the study area. Shrubland
communities to the right are associated with a moist to wet habitat where
the rainfall often exceeds 600 mm/a. Axis two illustrates a soil moisture and
soil structure gradient. Plant communities to the top are associated with
moist habitats, especially in drainage channels and other areas associated
with clayish soil. To the bottom of the diagram dry plant communities,
primarily associated with sandy soil, occur (Figure 11.3).
DISCUSSION
The Grassland Biome of South Africa, encompassing the grasslands of the
southern Free State, was identified by Greyling & Huntley (1984) as one of
the most critically threatened southern African ecosystems, with only
0.19% of the grassland area conserved. This confirms the necessity of
compiling a phytosociological synthesis as has been proposed by Scheepers
(1986).
This is the first comprehensive synecological account of the vegetation
of the southern Free State. The analysis of the large floristic data set of the
study area by means of the two-step technique (Bredenkamp &
Bezuidenhout 1995) has proven to be successful. The next step, a reduction
of the comprehensive synoptic class table to a synoptic table, where the
classes are represented by single columns, makes it possible to compare the
classes with ease (Du Preez 1991).
318
Sixteen phytosociological classes have been identified, a" of which are
strongly related to a specific habitat. Species from species groups 14, 19,
26, 27, 38, 41, 47, 54, 55, 59, 60, 61, 64, 65, 69, 70, 71, 75, 76, 77,
80, 82, 83 and 84 (Table .11.1) are the most abundant in the southern Free
State. All the other species indicate minor floristic relations among the
different classes (Table 11.1).
Although the classes are easily correlated with the habitat, there are
similarities and differences among the different vegetation units. A
combination of biotic and abiotic factors play an important role in the
distribution of the different vegetation units. The main contributing biotic
factors, which influence the distribution of the classes and degradation of
natural vegetation, have been identified as mismanagement of natural
pasture (eg. the uncontrolled ploughing of land) and overgrazing practices.
Abiotic factors such as soil depth, rockiness of the soil surface and rainfall
also play an important role in the distribution of vegetation (Figure 11.3).
The most important woody and semi-woody species encountered in the
southern Free State are Acacia karroo, A. mellifera, A. torti/is, Ce/tis
africana, Chrysocoma ciliata, Diospyros austro-africana, D.lycioides, Ehretia
rigida, Euc/ea crispa subsp. crispa, Fe/icia fi/ifolia, F. muricata, Grewia
occidenta/is, Lycium cinereum, Maytenus po/yacantha, a/ea europaea,
Osyris /anceo/ata, Pentzia g/obosa, P. incana, Protasparagus suaveo/ens,
Rhus burche/lii, R. ciliata, R. erosa, R. lancea, R. pyroides, Rhamnus
prinoides, Rhigozum obovatum, R. trichotomum, So/anum incanum,
Tarchonanthus camphoratus and Ziziphus mucronata.
Grasses of importance include Aristida edscenstonis, A .. congesta, A.
diffusa, Ch/oris virgata, Cenchrus ciliaris, Cymbopogon excavatus, C.
p/urinodis, Cynodon incomp/etus, Digitaria eriantha, Enneapogon desvauxii,
Eustachys paspa/oides, E1ionurusmuticus, Enneapogon scoparius, Eragrostis
capensis, E. ch/orome/as, E. curvu/a, E. gummiflua, E. /ehmanniana, E.
nindensis, E. obtusa, E. plana; E. superba, Fingerhuthia africana,
Heteropogon contortus, Microchloa caffra, Panicum cotoretum, Setaria
sphace/ata, Sporobo/us fimbriatus, Stipagrostis ciliata, S. obtusa, Themeda
~-------------- __ J
319
triandra, Tragus berteronianus, T. koelerioides, Trichoneura grandiglumis
and Triraphis andropogonoides.
The most abundant ferns are Cheilanthes eckloniana and Pellaea
ca/ome/anos.
According to Potgieter et al. (1995) veld degradation may be ascribed to
unfavourable climatic conditions accompanied by too high stock numbers.
The ecotone between the Grassland- and Nama-Karoo Biomes is best
illustrated in the differences between classes 9 and 10 (Table 11.1).
Cymbopogon p/urinodis (species group 47), Digitaria eriantha (species group
59) and Themeda triandra (species group 65) have much higher constancies
in the Themeda triandra-Cymbopogon p/urinodis grasslands of the western
plains than in the Hertia pallens-Prosopis ve/ut/na kartold vegetation of the
dry western Free State. Karroid shrub communities extend west along a
rainfall gradient (Rutherford & Westfall 1994). This supports Acocks's
(1979) hypothesis for an increase in shrub cover at the expense of grasses
across a wide expanse from the central and eastern Karoo through to the
grasslands of the southern Free State. This is illustrated in the higher
constancies of Hertia pal/ens (species group 48), Metotobium candicans
(species group 62), Sa/sola g/abrescens (species group 75), Protasparagus
suaveo/ens (species group 77), Eriocepha/us spineseens (species group 82),
Lyelum cinereum, Pentzia g/obosa, P. incana, Thesium hystrix and Lycium
horridum (species group 83) in the Hertia pettens-Prosopis ve/utina karroid
vegetation of the dry western Free State.
Other species frequently associated with habitat disturbance include
Asc/epias truticoss, Berkheya onopordifo/ia, the Karoo encroacher,
Chrysocoma ei/iata, Protasparagus tericinus, Tribu/us terrestris (species
group 76), Berkheya pinnatifida, Chenopodium a/bum, Protasparagus
suaveo/ens, Ta/inum caffrum, Wa/afrida saxatilis (species group 77), Sa/via
verbenaca (species group 80), as well as the grasses Aristlda congesta, A.
diffusa (species group 61), Eragrostis obtusa, Tragus berteronianus (species
group 76), Eragrostis /ehmanniana (species group 77), -Ch/oris virgata and
Eragrostis curvu/a (species group 80).
320
According to Rutherford & Westfall (1994) the usual progression, given
a significant reduction in grazing pressure and a suitable distribution of
rainfall (Vorster & Roux (1983); is a steady increase in cryptophyte cover
and a maré variable decrease in chamaephyte cover. The soils of the moist
grasslands, however, are usually more leached by the higher rainfall and
tend to be dystrophic in comparison with generally eutrophic soils of the
drier areas (Rutherford & Westfall 1994). The southern Free State, however,
seems to have a broad transition zone of shrub-grass mixtures and thus
emphasize the necessity for future management programmes to be
implemented in this region.
Although veld degradation occurs in all the Broad Homogeneous Zones
of the Free State (Fuls 1993), each area has an own identity and
characteristic pattern of veld degradation and must be approached
individually. In the southern parts, early stages of degradation can be
observed in deterioration of the plant cover, followed by a change in the
plant species composition. In the northern and eastern parts of the Free
State, the pattern is reversed - composition changes first, followed by
deterioration in plant cover (Potgieter et al. 1995).
1
Table '1'1 1.11A: synoptic table of the synrelevés of the vegetation classes of
the southern Free-State~
12223345667891111111
CLASS NUMBER ..... 0123456
12312 12
SPECIES GROUP 1
Leucosidea sericea 4 1 2
Rhus dentata 3 Il
Cussonia paniculata 3 11
Helichrysum rugulosum 3 1 21
Rosa eglanteria 3 1
Myrsine africana 21 1
Buddleja salviifolia 2 1 1
Salvia namaensis 2 11 1
Senecio isatideus 2 2
Tristachya leucothrix 2 2
H~licnrysum pilosellum 2 2 2
Cliffort'ianitidula 2 1
Rhus dregeana 1 1
SPECIES GROUP 2 ~
Stoebe plumosa 4
Eucl.eacrispa subsp. crispa 3
Passerina montana 3
Cliffortia paucistaminea 2
Peucedanum capense 2
Aristea cognata 1
Helichrysum appendiculatum 1
Pelargonium alchemilloides ·1
~
SPECIES GROUP'3
Aloe ferox
Helichrysum pilosellum
SPECIES GROUP 4
Euclea crispa subsp. ovata 244 2 Il 1
Buddleja saligna 1 31
Delosperma pottsii 1 I
Eragrostis echinochloidea III 1 1
Homeria pallida III
Pelargonium abrotanifolium 1 1
Crotalaria éremicola 1 1
Protasparagus capensis 1 1
Urtica dioica
Garuleum pinnatifidum l 11 1
Vicia sativa 1 1
Conunelinaeckloniana' 1 1. Il
2
12223345667891111111
CLASS NUMBER ..... 0123456
12312 12
Opuntia specf.ës 1 1 1
Scilla nervosa 1 1
Moraea spathu.lat-a 1 1
Sutherlandia microphylla 1 1 1 1
Lithospermum cinereum 1 1
SPECIES GROUP'5
Kleinia longiflora
Sisymbrium capense
Sisymbrium t.hellungii
Trachyandra aspera
SPECIES GROUP 6
Zinnia peruviana . 21 1
Opuntia ficus-indica, 11 1 1.
Tragus racemosus 11 1 1
Populus canescens 11 1
Hermannia amoena 11 1
Prunus persica 11.
Achyranthés a@á.tica 11
SPECIES GROUP 7 .
Sesamum capense 111 11 1
CotoIieaster species 111
Sutera filicaulIs 111
SPECIES GR()UP 8
Argyrolobium Lanceof.at.um 4 3
Lotononis Laxa- 31 1
Brachiaria serrata 3'1 32
Hermannia linearifoliêl 31 1 11.
Phyllanthus;maderaspatensis 31 1 1
Helichrysum lucilioides 31 1
Sutera halimifo'lia 311
Blepharis villbsa 21 1
HermanniapUlverat.a 21 1
Helichrysum niveum 21 2
Polygala unefrrat.a 1 21 1
Sutera at:tbputpUrea 11 21 1 1 1
Pteronia glauca 12 1 1 1
CrasSula capiE'ella: 1 21
Phymaspennurrr aciculare 2 1
Rhus divaricata 1 1
WithaIiia somnifera 1 1 1
3
12223345667891111111
CLASS NUMBER ..... 0123456
12312 12
SPECIES GROUP 9 --
Anacampseros lanceolata 2·
pelargonium aridum 2
Athrixia angust.issima.' 1
Bidens pilosa, 1
Chamarea capensd.s 1
Crassula exilis, 1
Gerbera viridifolia 1
Haworthiá téssellaEa 1
Helichrysum rosum 1
Heliophila suavnasdma 'i
Hennánnia species 1
HypoxiS:hemerocallidea, 1
Hypoxis iridif'olia 1
Kalanchoe rotundif()lia 1
Kalanchoe thyrsiflora '1
Koeleria:capensda ,1
Polyga:lae:phedroides 1
Sanseviera aethiopica 1
SClIistostephiumcrCitaegi.fol.iuïnI,
SchizoglosSu,mlinifoliull1 1
Senecio hieracioides 1
Senecio inornatus 1
Senecio lati:folius 1 ,
Senecio retorsus 1
Setaria lindenbergiana -1-,
SPECIES:GROUP' 10
Solanum,cocc'sneum 1, 23 2,
viscum rotundi-fol.ium 1 23 1 1
senecio bu:-rchellii 1 11 1 1
Argyrolobium,pauci,florom 1 l·I. 1
Këilalichopea'nicuê.at.a 1 11 1
Rhynchos,ianervosa 1 11
Haemanthus humiiis i 11
Hermannia'cunelfolia 14 1
Cotyledon o:r:biculata 13 2
Pachypodiunisuceuáentrum 11 1 1
Stape'l,igarandiflora 11 1
Lightfootia nodo-sa 11 1 1
Pseudognaphalium luteo-album 11 1 1
PtipaliaLappacea Il Il
Elephantorrhiza elephantina 11 1
Coccinia sessilifolia 11 1
protasparagusc denUda:tus Il 1
Hêt'eromorphaerifo'1iat'a: 11 1 2
Maytenus'het'erophyl1a 11 1
Ehrharta erec'ta 11 1
4
12223345-6:6789'111111:1 '
CLASSNUMBER' ... ' .. ' 0123456
12312 12
Rhynchosia' totta: 11 1
SPECIES GROUPli
Cheilanthes, hirta 13, ,
Adrom:ischus t:tifclórus 12
Aloe bróómii 12, ,
Moh-ria ëaff:torunf :12-•
Boophanedisticha ,11 ;
Ceterach' corda'tum 11
Cheilanthes, "i:t1dis: 11,
CommeliIia benglia.lérisiS 11 '
Dimorphothecacuneata 11
Gerbera: piloseJtloides il
Pelargonium, myrrhifolium: 11 '
Schoenoxiphium spaz.t.eum 11
SPECIES GROUP12
Gnidia m:icrocephala
Vernonia capensis
Linum thuriI:5ergii
SPECIES GROUP1~:3,
Sutera, albiflora 11A'! i 1 3
Pollichia campe'scris 114 1 1
Melinis' répens- 212 1 1
SPECIES GROUP14
Rhus erosa 54-34 2
Olea europaea subsp. africana 3444 1 1
Pa'vorï.i.a bur-diéll i i 1221 21
Cel Eis af':t-icana '1312 2
Diospyros aust:c:tó-af:tic'ana 4434, 1 1 1
Rhigozum obevat.utn 1322 1 22 1
Cheilanthes eckloniana 323:3 1.1 13
Maytenus polyacantha- 1122- 11 11 1
Pellaea calorttelanos: 3224 2 11
Cymbopogori excavatus '1212 1
Lantana rugosa 1123 2 2
Pentz,ia' aphaeasoeephaê.a 2112 1 1
Rhamnus' prinoides' 2311
Osyris lanceolata 4122
Grewia occiden.tal-is 1411
Rhus pyroide-s' .subsp, gracilis: :1211
Clutia pUlchella- 2'111
5
'1:2223345667891lcl1111
CLASS' NUMBER .. . . . .. 0123456 '
12312 12
SPECIES, GROUP 15
Rosenia- humiiis 153 3 1
Conyza bon.ariensis 1141 3 :211 1
Cyperlls uSi t'á,t\l's' 14 11 3
Sporobolus ludwigii 4 1
Digitaria .argyrograpt-a: 113 22
Eriochloa parvispiculata 113
Barleria macrostegia 1-3 1 l- I
Chamaesyce inaeqUilatera 13 1
Dimorphotheca zeyheri 13 1
Pentzia vilddis 13 2
Mestoklema- arborifonne 13 1
Ornithogalum prasinum 13 1
Ledebouria, luteola 13 2 1,
Pentzia sp:inescen.s 121:2
Bulbine' abyssinica' 12 2 ]:
Medicago poiymorpha 12 1
Arc tot'is venUs~t:'a 1 2 1 1 1
Kyllinga' alba 2- 1 2:11
sals'ola rabie'ana ,:2 1:2
Eragros'tis; bieblor' 2: 21 2 1
TUlbaghia acut-iloba 1 1 II
Bulbine nare'is's~fibI iá: 1 1 1 1 1
Conttnicarpus pêntandru's' 11 1
Dipcadi viride 1-1. 1
Massonia j'asminiflora 11 1
Felicia flan.agan.ii 11 1
Sute:ra piIiIiatif'ida 1 11 1
Senna italica 11 1 1
CrasSula sêtulosa 111
SPECIES GROUP 16 r'--
DUthiastrum linifolium 2
Kyllin.ga alata 2
Menoddra afr'icana 2
Brachiaria eruciformis 1
Gethyllis uiidulata. l'
Moraea polystachya 1
Oenothera tetraptera 1
'-- '
SPECIES GROUP 17
Dianthus basutic'us 42' 1
Trichodiadema pomeridianum 22 1
Blepharis in:eegrifdlia 34 2
Hibiscus marldthianus 33, 1 2
Cynddoii'hirtëlhis ;2:3 2 13
Aptosimum procurtlbens 22 1 1
6
12223345667891111111
CLASS NUMBER ...... 0123456
12312 12
SPECIES GROUP 18 -
Thesium spartioides 3,2
Euphorbia clavarioides 22
Euclea coriacea 21
Nanartthus vittatus 21
Osteospernrum leptoldbum 21
Stachys burchelliana 21
Crassula nluscosa 12
Galenia pubeseens 12
Raphionacme hirsuta 12
Albuca shawii 11
Andropogon appendiculatus 11
Aristida junciformis 1:1
Helichrysum caespititium 11
Melolobiu.tncalycinum ~1
Nolletia ciliaris 11
Sutera argentea 11
Wahlenbergia denticulata 11
L...--
SPECIES GROUP 19
Helichrysum dregeanum 142 1 131
Solanum supinum 143 22 1 2
Plexipus pinnatifidus 142 11 1
Cineraria lyrata 112 1 2 2
Sutera caerulea 111 11 1
Indigofera sessilifolia 1 121 1 1 1
Helichrysum zeyheri 1411 1
Corbichonia decumbens 121 1 11
Lightfootia a'lbens 1 141 1 1
Turbina oenotheroides 111 1 1
SPECIES GROUP 20
Turbina oblongata 1111
1 11
I SPECIES GROUP 21Hermannia erodioides 124
Salvia disermas 1 1 4 11
Stipagrostis uniplumis 1 31
Sal sola calluna 113 1
Aptosimum indivisum 11 2 1
Argemone ochroleuca 1 12 2 1
Indigofera nigromontána 1 2 2
Barleria irritans 1 2
Cotu.la anthemoides 1 2
Medicago laciniata 1 2
7
12223145667891111111
CLASS NUMBER ..... 0123456
12312 12
Monechma divaricatum 1 2
Phyllanthus burchellii 1 2
Sanseviera species 1 2
Sutherlartdiët frutescens 1 2
Hibiscus lunarifolius 1 1
Veronica. anagilis-aquatica 1 1.
SPECIES GROUP 22
Syncarpha argyropsis
SPECIES GROUP 23
Phaeoptilum spinosum 1 5
Dicoma tnacrócephala 21 4
Plinthus karo6icus 1 4 1
Schizoglossum capitatutn 1 4
Eragrostis porosa 1 41
Pentzia calcarea 41
peliostomum lêucó:t:thizutn· 11 3
Aptosimum spinescens 1 3 1
Plinthus cryptocarpus 1 3·
Hermannia spinosa 1 3
Monechma incanutn 1 3
PSilocaulon absimile 1 121
Senecio longif'olia 11 2 1
Phyma.spertnum parvifolium 11 2
Eragrostis truncata 1 22 1
Boscia albitrunca 11 121
Gnidia capitata 1 2'
Aloe clavi flora 1 :2
Pteronia sordida 1 :2
Tetragonia arbuscula 1 2
Kohautia· amatymbica 11 1
Drosanthemum species 1 1
Sarcocaulon salmoniflorum 1 1
SPECIES GROUP 24 ...--
Nolletia arenosa 3
Zygophyl.lum gil.fillan-ii 3
Aptosimum albomarginatum 2
Euphorbia aequoris 2·
Coelachyrum yemenicum 1
Hoodia gordonii 1
RhynchopsidiUIIi puIIiilum 1
~
SPECIES GROUP 25
Abutilon auat.ro=afrdcanum
8
122233'45667891111111
CLASS NUMBÉR ..... G123456
12312 12
Cadaba aphyllá I, 1
Mic:r'oloma'arrtlatum 1 1
polygal.a asbestina 1 1
Psatmnotropha: m.ucI'onáta 1 1
Walafrida' geniculata 1 1
SPECIES GROUP 2'6
Gnidia polycephala 3245 2
Helichrysum asperum 2242 2
Osteospermum: scariosum 2221 2
Aptosimum marlothii 2125 1
Melolobium microphyllum 1 4321 1
Enneapogon desvauxii 23351
Pegolettia I'etrbfractél 4112
Aristida, adscensionis 3113
Aptosimum: deoumbens 2111
Lessertia' paucifl-ora 22 3 2
Kyphocarpa angustilfolia 2 13 1
Erioceplialus' pubéscens 31 5
Polygala leptophylla 21 5'
SPECIES GROUP 27
Indigofera alternans "144 51, 1 1
Limeum aethiopicus
1,132.4 1 11
SPECIES GROUP 28
Melica decumbens 1112 5
Achyranthes aspera 11 5
Clematis brachiata 311 4
Setaria verticillata 111 14
Bromus catharicus 11 4
Rhus pyroides subsp., pyroides 1 1 4
Cineraria lobata, 111 3
Protasparagus c90peri 11 3
Ant izoma' angustifolia 11 13
Lepidium african'um, 11 2 3
Bidens bi.pd.nnatia: 1 3 1
Pentarrhinum insipidUlYl 1 3
Urochloa panicoides 1 2 1 11:
Solanum: retroflexum 11 2 1 1
Sonchus oleraceus 11 2'1
Delosperma cooperi 1 1 2 1
Silene, undulata 1 2
opunt.La vulgaris' 1 2
Rubia petiolaris 1 2
9
12223345667891111111
CLASS NUMBER ... ~. 0123456
12312 12
Protasparagus setaceus 1. 2
Al ternanthera punqens 21
Ammocharis coraIiiëa 1 1
Papaver aculeatum i 1
Sphaeralcea bonariensis 1 1 1
Salvia repens 1 1
SPECIES GROUP 29 ,.:--'
Chenopodium murale' 2
Hebenstret'ia int'egrifhlia: 2
Rubia horr'ida 2
verbena officinalis' 2
L._-
SPECIES GROUP 30
Delosperm:a mahonii I 1
Lappula squar roaa 1 1
Limeum sulcaeunr 1 1
Protasparagu's glaucus' 1 1
Trichodiadema barbatum 1 1
SPECIES GROUP 31
Crassula lanceolata 1111 2
Teucrium trifidum 1111 2 1
SPECIES GROUP 32
Oxalis corniculata 311 3 1 1
Melianthus comesus 1111 .2 11
SPECIES GROUP 33
Acacia tortilis 11 2 5'1 1
Grewia flava 1 21
Hermannia b:tyoniif'cHfa 11 21 11
SchInidtia pappophoroides 1 11 1
Enneapogon cenchroides 1 11 I
Prosopis chilensis 11 1
Acacia erioloDa 1 1
Mestoklema. tuberosum 1 1 11
Kedrostis a.fricana 11 1
Schmidtia kal,aha.riensis 1 1
Blepharis dive'rsispina I 1
10
122233-4566-7891111111·
CLASS NUMBER . . . . . . . 0123486
12312 12
SPECIES GROuP 34- _.~
AHcealciioaphilhae.becclaardnaosa. .ill
Herm:a:nnia:m.od'e"s-t"a .
SPECIES GROUP 35
polygala hott~ntotta l1i 2 i
Solanum panduriforme. 111 111 .r
MeliIiis' nerv:iglume 111 11
SPECIES GROup· 36
Phyllanthus parvulus: ii 2 i :2
Enneapogbn scaher 1, 1- 1 1.
Melha:nia: rehmanrl:i:i- 1 1 1
Justicia cU:héat'a 1 1
SPECIES GROUP 37
Abutilon pycnodon
Cullen' obtU's'ifolia ~l
Justicia: protracea l~J
SPECIES GROUP .- --38
Acacia mellifera ii ij 3·3 1
Cenchrus cfliar1s' 11 2 31 11
Tarchonan:thus catIipho:ta:tus: 24 2- 34 1
_.'_ . >. ~ ~
SPECIES GROUP 39·
Aristida hipa-rtitëf 1 i 4
Crabbea acaulis· 1- 3
Mons"c)Il·iaa:nguáti een fa: 111 3 1 2
Conyza podocephala: 1 1 3 1
Scabiosa' columbaria 11 11 2 1
Sporobólus discbpofu's J. 2' 1 2"
pogonaithria squarrosá 1 11
Ruschia specieS 1 1
oenocher'e st.ricta 1 1
SPECIES GROUP 40
Lactuca serrioia @]
SPECIES GROuP 41
Eragrostis chloromelas li332 i 521 I
11
12223345667891111111
CLASS NUMBER ..... 0123456
12312 12
Cynodon dactyl'orl 1112~ 2 13 111
SPECIES GROUP 42
Oenothera indecora 1 1 41
Sutera aurantiaca 112 1 41 1
Berkheya d'is'c'oior 11 4
Eragrostis raéémosus 1 11 3
Buz'yop's anilae 1 3
Panicum stapffanum, 1 1 3 i
Stoebe vulgariS' 1 12
Helichrysum nud'i.f.ol·itim 1 1 12
Dicoma anomala 1 1 12
Euphorbia striata 1 12
Lactuca capens·is· 11 12
Lotononis tenel-la 11 1 2'
Ajuga ophrydis 1 2
Haplocá.:r'pascaposa 1 2·
Harpoc:hloa falx 1 2
Helichrysum longifolium 1 2
He:tiiiá:IiIiiaqua:tEiniana 1 2
Hibiscus aethiopicu.m: 1 2
pentaschistis setifolia 1 2
Pdlyga:la a'ma.tyrtlbica 1 z
Senecio co'ronat.us' 1 2
Sute:ta:krau.s·s:ia:na: 1 2
Trachypogori spicátus 1 2
Stenostelma 'capense :2 :2
Aloina species 1 2
Brunsvigia radulosa 1 1 21
Lot'onon'is 1i s·tii 1 21
Senecio erubescens 1 21
Wahleribergia undulata 21
SPECIES GROUP 43
Cymbopogon dieterlenii
Ficinia species 2
Hermannia gerticuiata: 2
Selago galpinii 020
SPECIES GROUP 44
Eragrostis plaha 1 1 551 1
Trichoneura grand::Lglumis 111 44
Eragrostis gumtnifClua~ 11 1 342
Micrdch16a caffra 11 331 3
Eragrostis capehsis 1 1 251
12
.12223345667891111111
CLASS NUMBER ..... 0123456
12312 12
Hermannia depressa 111 24
Pennisetum sphacelatum 11 22
Lightfoot.ia denticulata 111 22
Walafrida densiflora 12 2 14 1
SPECIES GROUP 45
Sal sola kali Il III 21 11
SPECIES GROUP 46
Arctotis arctotoides
Dipcadi glaucum
Hypoxis filiformis
Tragopogon dubius
~
SPECIES GROUP 47
Cymbopogon plurinodis 323531 111553 1
Salvia stenophylla 1 11 1 13 1
Elionurus muticus 2 132 351
Helichrysum callicomum 1 11 1 1211
Hibiscus pusillus 1 1552 2 221
Hermannia comosa 113 21 1 1
SPECIES GROUP 48
Hertia pallens 1 1 1 1 12 1
panicum schinzii 1 1 11 1
Helichrysum lineare 1 11 1
Zygophyllum incrustatum 1 1 1
Stipagrostis namaquensis 1 1 1 1
SPECIES GROUP 49 -
Amaranthus thunbergii 1
Deverra denudata 1
Eragrostis bergiana 1
Galenia africana 1
Geigeria ornativa 1
Hertia ciliata 1
prosopis velut"itïá 1
psilocaulon junéeum 1
pteronia incana 1
Ruschia rigida 1
Stachys hyssopoides 1
Suaeda fruticosa 1
Zygophyllum inacrocarpon 1
13
12223345667891111111
CLASS NUMBER ..... 0123456
12312 12
Zygophyllum 'microphyllum
SPECIES GROUP 50
Eriocephalus ericoides
SPECIES GROUP 51 '"
Becium angust:bfolium
Flaveria bidentis
Thesium strictum 01
SPECIES GROUP 52
Eriocephalus, aspalathoides
Saltera sarcocolla . D•
SPECIES, GROUP' 53
Pterothrix spinescens 33 1 2 1
ConvOlvulus boedeckerianus 23 11 2 1
SPECIES GROUP, 54
Gazania krebsiana 114424,1.24,11 1
Solanum incanum 112 1 2221 1
Ziziphus niucronata 223 2 422 1
Ehretia rigida 124 12133 11 2
Selago albida 1231 11 11
Osteospermummuricatum 11 111 11
Protasparagiis: striat:u:s~ 122 12 1
Aloe grartdident.ata 111 111 1
SPECIES GROUP 55
Felicia muricata 11255224123222 1,
SporobOlus fimbriatus 1225221424 421-.11
Setaria sphacelata 111221 2 5521
Eragrostis superba 11·12311.11-211
Rhus ciliata 1;24412111 111
Enneapogon scoparius 11243 132 1 3 '
Felicia f:rlifolia 5233 111311
Triraphis artdropogónoides' 1 111 11211
Hermanniat vest.ita 1 1213 12 11
Pseudog'naphaliurttlu:teo-=album 1 112 2 1 11 11
Stachys rugosa 1 22 2 11 1
14
12223345667891111111
CLASS NUMBER ..... 0123456
12312 12
SPECIES GROUP' 56
Oropetium capen:se 13 21 5
Eragrostis nindensiS 1 11121 1 1.4
Eberlanzia spinosa 111 3 1 14
Euphorbia mauritanica 11 1 13
Senecio rádicans 1 3
Anacamps'eros truncata 1 1. 3
Chasmatophyllum·musculinum 11 1. 3
Crassula nudicá.u'lis 11 3
Sarcostennna; viminale 11 3
Bonatea speciosa 11 2
Euphorbia rect'irama' 11 1 2
Crassula dependeris- 1 2
Pteronia species 1 2
Orbeopsis lu.tea 11 1 1
Albuca setosa 1 1
Gladiolus permeabilis' I 1
Adromischus tr;i.gynus 1 1
Helichrysum spec'Les 1 1
SPECIES GROUP 57
Anacampseros filamentosa 4
Stomatium mustellinum 4
Anacampseros' ustulata 3
Crassula corallina 3
Neohenricia sibbettii 2
Otholobium prodiens 2
Trachyandra saltii 2
SPECIES GROUP 58
Anthospermum rigidum 32
Mariscus capensis 32
1.
SPECIES GROUP 59'
Tragus koelerioides ·155351 52112
Digitaria eriantha 3532 223 54'11
Commelina africana 123 11 1 1 2
SPECIES GROUP 60'
Hermannia coccocarpa 1134411 113111
Geigeria filifolia 1123241 1121 2
Eustachys paspaloides' 1251 11 21.1
.Nenax microphylla 1133 1 2 2111
15
1222~345667g91111111
CLASS NUMBER .,.0. 012345612312 12
SPECIES GROUP 61
Heteropogon contort\)$ 334533114535111
Aristida congesta 12355S522334322
Aristida diffusa 2235312 3212223;
SPECIES GROUP 62
Phra.gmites au:stralis 1 1 52
Salix rrtucronata 1 51
Verbena bonariensis 1 2 11 11 4
Rumex lanceolatatu.s 1 1 42
Cyperus longus 2 1 432
Lactuca dregea.na 1 1 212
Paspalum dilatatum 1 1 1 11 21
Oenotherac rosea 11 2 21
cynodon incompletus 11 2 1 11 221
Melolobium candicans' 11 1 12 12 2 1
Euryops multifidus 1 1 1 112
Thesiu:m species 1 11 1 2
Sida dregei 11 1 2
Phyla, nodi flora' 1 1 1 2
Convolvulus arvensis 1 1 1 2
Schinus niotle 1 1 2
Leucas martinicensis 1 1 2
Equisetum ramosiss'imum 1 2
Scirpus inanis 1 2
Gomphostigma virgatum 1 2
Tetrachne' dregei 11 2
Nicotiana glauca. 1 21
Miscanthus capensis 1 211
Ranunculus multifidus 2 1
SPECIES GROUP 6·3
Salix babylonica 5
Conium chaê]:;ophylloides 2·
Datura ferox 2
Hemarthria altissima 2
Mentha longifolia 2
polygonum kita:ibelianum 2
SPECIES GROUP 64
Acacia karroo 213211511 1 41
Tagetes mi.nut.a- 31 3 1 21 411
16
12221345667891111111
CLASS NUMBER r.r.. 0123456
12312 12
SPECIES GROUP 65
Themeda triandra 555553 224555112 1
Rhus burchelIii 3344.31112 2 1 2
Oxalis depressa 11214 3 121112
Rhus Lancea 1321 1 1 1 1 2
Artemisia afra 1211 2 1 1 2
SPECIES GROUP 66
Mariscus cortgestus .1 1 11 41
Cyperus rupestris 1 1 1 3 31
Medicago sativa 1 11 3
Agrostis lachnantha 1 1 1 21
Juncus rigidus 1 2
Pulicaria scabra 1 1
SPECIES GROUP 67
Persicar-ia serrulata 4
Cichorium intybus 2;
Alternanthera nodiflora 1
ConvolvulUs sagittatus 1
Cyperus eragrostis 1
Schoenoplectus paludicola 1
SPECIES GROUP 68
Typha capensis
Juncus exsert1,ls
SPECIES GROUP 69
Nidorel1a resedifol-ia 113 3 11 211.3
Atriplex semibaccata 112 5 1 11 2
SPECIES GROUP' 70
Lycium. hi·rsutum 21113 5 11 1
panicum maxdmum 211 2 1 11 2
SPECIES GROUP 71
Diospyros lycioides 3525 1 51 1 1 43
Hyparrhenia hirta 2212 1 3 1
Vahlia capensis 1 1 2 21 2
Salvia runctnat'a 1 111 1 1 1 1
Euryops empetrifolius 1111 111 2
Hyparrhenia dregeana 1-1·1 1 1 2
17
12~233456678'91111111
CLASS NUMBER. ..... 012345'612312 12
SPECIES GROUP 72
Lobelia thermalis 1 ;2 11 4
Cirsium vulgare, 1 1 1 213
wahlenberg'ia .andzosacea 111 1 2
Sci:tpus nodosus 1 2
Fuirena hirsuta 1 1
Sporobolus' virginicus 1 1,
Atriplex nummularia' 1 1
SPECIES GROUP TJ.
Phragmites maurit.ianus
Scirpus dioecus
Sporobolus: t'ei:1ellu's~
Cyperus laevigatus
Cyperus species
SPECIES GROuP 74
Juncus kraussii ~
Portulaca oleracea ~
S:PECIES GROUP 75
Sal sola glabrescens 12335,21 13 2
Xanthium spinosum 1 1 11 1 1
Cyperus' marg$na.'tuS: 11 2 1 11 223
SPECIES GROUP 76:
Eragrost1s' obtusa 115'5:53222533312
Chrysocoma, ciliati:r 235455333 333 2 1
TragUs' bert'eronianus ,1111251 13 211 2
protasparagus' laricinus '3231 4421 11 421
Asclepias fruticosa 111 2 1 211 242
Berkheya bnopordifolia 1111 1 13221 1:
Tribulus terrest:tis 11 121 11 4 1
SPECIES GROUP 77
Eragrostis lehmatiIliana 12355'5531323431 2
Protasparagus suaveolens 1335245534 121 11
Berkheya pirtnat'ifida 21114213 15 21 2 1
Chenopodium album 11121 2331 21 12
Walafrida saxatilis 13245 13 2 322 1 .
Talinum caffrum ·1 134 22211 1 1
18
12223345667891111111
CLASS NUMBER ..... 0123456
12312 12
SPECIES GROUP 78
Hibiscus trionum 12112 1 1 1 5
Schkuhria pinnata 1 111 2 1 5
Setaria incrassata 221 1 1 5
Xanthium strumarium 11 1 22 5
Rumex crispus 1 1 1 22 5
SPECIES GROUP 79
Diplachne fusca
SPECIES GROUP 80
Salvia verbenaca 111121 1 1 21 21 5
Eragrostis curvula 242533 4322532 2 15
Chloris virgata 112313113 21 15
SPECIES GROuP 81
Helichrysum pentzioides 1 1 1 1 1 5
Aristida canescens 11 3 1 3
Lycium pilifolium 3 1 2 3
Sporobo~us ioclados 1 1 2 3
Osteospermum spinescens 1 1 3
Protasparagus mucronatus 1 2 1 3
SPECIES GROUP' 82
Eriocephalus spinescens 3213 21 23
1 31
SPECIES GROUP 83'
Lycium cinereum 211 215113 13 Il 3
Pentzia globosa 243523424334 2 2 3
Fingerhuthia africana 13243133 2 5
Pentzia incana 113 5211 12 1 3
Stipagrostis obtusa 11 5 11 1 5
Barleria rigida 12 15 22 1 3
Rhigozum trichoEomum 11 4 11 1 3
Thesium hystrix 1224311 2 3
Stipagrostis ciliata 11 4 1 3
Lycium horridum 1 21 2 1 3
SPECIES GROUP 84
Ruschia hamata 21111 1 12 Il 3
Panicum' coloratum 1,1141 1 5 21 2 3
321
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330
CHAPTER 12
Vegetation ecology of the southern Free State
Vegetation ecology of the southern Free State: A floristic analysis.
331
CHAPTER 12
VEGETATION ECOLOGY OF THE SOUTHERN FREE STATE: A
FlORISTIC ANALYSIS.
A checklist of all the species collected and recorded during the survey is
presented. The families and species are arranged alphabetically (Bryophyta,
Pteridophyta, Gymnospermae, Monocotyledonae and Dicotyledonae
separately), thus making quick reference easier. Taxon and author names
confirm to those of Arnold & De Wet (1993). Naturalized exotic taxa are
marked with an asterisk (*).
The relationship between the number of families, genera and species of
Bryophyta, Pteridophyta, Gymnospermae, Monocotyledonae and
Dicotyledonae is given in Table 1. The most prominent families and genera
are given in Tables 2 and 3 respectively. A list of all the naturalized exotic
species is presented in Table 4.
BRYOPHYTA
Pottiaceae
Aloina sp. (Malan 1122, BFlU)
PTERIDOPHYTA
Adiantaceae
Cheilanthes eckloniana (Kuntze) Mett.
C. hirta Swartz var. hirta
C. quadripinnata (Forssk.) Kuhn
C. viridis (Forssk.) Swartz
332
Pellaea calomelanos (Swartz) Link
Aspleniaceae
Ceterach cordatum (Thunb.) Desv.
Azollaceae
Azolla filiculoides Lam *
Equisetaceae
Equisetum ramosissimum Desf.
Schizaeaceae
Mohria caffrorum (L.) Desv.
GYMNOSPERMAE
Cupressaceae
Cupressus torulosa D. Don *
ANGIOSPERMAE
MDNOCOTYlEDONAE
Alliaceae
Tulbaghia acutiloba Harv.
333
Amaryllidaceae
Ammocharis coranica (Ker-Gawl.) Herb.
Boophane disticha (L. f.) Herb.
Brunsvigia radulosa Herb.
Crinum bulbispermum (Burm. F.) Milne-Redh. & Schweick.
Gethyllis undulata
Haemanthus humilis Jacq.
Nerine laticoma (Ker-Gawl.) Dur & Schinz
Asparagaceae
Protasparagus capensis (L.) Oberm.
P. cooperi (Bak.) Oberm.
P. denudatus (Kunth) Oberm.
P. glaucus (Kies) Oberm.
P. laricinus (Burch.) Oberm.
P. mucro natus
P. setaceus (Kunth) Oberm.
P. striatus (L.F.) Oberm.
P. suaveolens (Burch.) Oberm.
Protasparagus sp. (Malan 227, BFlU)
Asphodelaceae
Aloe broomii Schon!.
A. claviflora Burch.
A. ferox Mill.
A. grandidentata Salm-Dyck
A. hereroensis Engl.
Bulbine abyssinica A. Rich.
B. narcissifolia Salm-Dyck
Haworthia tessellata (Salm-Dyck) Bak.
Trachyandra asperata Kunth
334
T. saltii (Bak.) Oberm.
Commelinaceae
Commelina africana L.
C. benghalensis L.
C. eckloniana Kunth
Cyperaceae
Carex schlechteri Nelmes
Cyperus bellus Kunth
C. difformis L.
C. eragrostis Lam. *
C. laevigatus L.
C. longus L.
C. margaritaceus Vahl
C. marginatus Thunb.
C. obtusifloris Vahl.
C. rupestris Kunth var. rupestris
C. usitatus Burch.
Cyperus sp. (Malan 861, BFLU)
Ficinia sp. (Malan 480,- BFLU)
Fuirena hirsuta (Berg.) P.L. Forbes
Kyllinga alba Nees
Mariscus capensis (Steud.) Schrad.
M. congestus (Vahl) C.B. CL.
M. indecorus (Kunth) Podlech
Pycreus macranthus (Boeck.) C.B. Cl.
Schoenoplectus paludicola (Kunth) Palla ex J. Raynal
Schoenoxiphiurn sparteum (Wahlenb.) C.B. Cl.
Scirpus dioecus (Kunth) Boeck.
S. inanis (Thunb.) Steud.
S. nodosus Rottb.
335
Dracaenaceae
Sanseviera aethiopica Thunb.
Hyacinthaceae
Albuca setosa Jacq.
A. shawii Bak.
Dipcadi glaucum (Ker-Gawl.) Bak.
. D. vi ride (L.) Moench
Eucomis autumnalis (Mill.) Chitt.
Massonia jasminiflora Burch. ex Bak.
Ornithogalum cf. dubium Houtt.
O. prasinum Undl.
Polyxena cf. odorata (Hook. f.) Bak.
Scilla nervosa (Burch.) Jessop
Ledebouria luteola Jessop
L. ovatifolia (Bak.) Jessop
Hypoxidaceae
Hypoxis filiformis Bak.
H. hemerocallidea Fisch. & Mey.
H. iridifolia Bak.
Iridaceae
Duthiastrum linifolium (Phill.) De Vos
Gladiolus permeabilis Delaroche
Homeria pallida Bak.
Moraea polystachya (Thunb.) Ker-Gawl.
M. spathuiata (L. f.) Klatt
336
Juncaceae
Juncus exsertus Buchen.
J. kraussii Hochst.
J. rigidus Desf.
Orchidaceae
Bonatea speciosa (L.f.) Willd.
Poaceae
Agrostis lachnantha Nees
Andropogon appendiculatus Nees
Anthephora pubeseens Nees
Aristida adscensionis L.
A. bipartita (Nees) Trin. & Rupr.
A. canescens Henr.
A. congesta Roem. & Schuldt
A. diffusa Trin.
A. junciformis Trin. Rupr.
Arundo donax L. ..
Brachiaria eruciformis (J.E. Sm.) Griseb.
B. serrata (Thunb.) Stapf
Bromus catharticus Vahl *
B. unioloides H.B.K.
Bromus sp. (Malan 82, BFLU)
Cenchrus ciliaris L.
Chloris virgata Swartz
Coelachyrum yemenicum (Schweinf.) S.M. Phillips
Cymbopogon dieterlenii Stapf ex Phill.
C. excavatus Hochst.
C. plurinodis Stapf
Cynodon dactylon ( L.) Pers.
337
e. hirsutus Stent
e. incompletus Nees
Diheteropogon filifolius Nees
Digitaria arqvroqrapta (Nees) Stapf
D. eriantha Steud.
Diplachne fusca (L.) Beauv. ex Roem. & Schuit.
Ehrharta erecta Lam.
Elionurus muticus (Spreng.) Kunth
Enneapogon cenchroides (Roem. & Schuit.) e.E. Hubb.
E. desvauxii Beauv.
E. scaber Lehm.
E. scoparius Stapf
Eragrostis bergiana (Kunth) Trin.
E. bicolor Nees
E. capensis (Thunb.) Trin.
E. chloromelas Steud.
E. curvula (Schad.) Nees
E. echinochloidea Stapf
E. gummiflua Nees
E. lehmanniana Nees
E. micrantha Hack.
E. nindensis Fical. & Hiern
E. obtusa Munro ex Fical. & Hiern
E. plana Nees
E. porifolius Nees
E. racemosa (Thunb.) Steud.
E. superba Peyr.
E. trichophora Coss. & Dur.
E. truncata Hack.
Eriochloa parvispiculata e.E. Hubb.
Eustachys paspaloides (Vahl) Lanza & Matthei
Fingerhuthia africana Lehm.
Harpochloa falx (L.f.) Kuntze
Helictotrichon turgidulum (Stapf) Schweick.
Hemarthria altissima (Poir.) Stapf & e.E. Hubb.
Heteropogon contortus (L.) Roem. & Schuit.
338
Hyparrhenia dregeana (Nees) Stapf
H. hirta (L.) Stapf
Koeleria capensis (Steud.) Nees
Melica decumbens Thunb.
Melinis nerviglume (Franch.) Zizka
M. repens (Willd.) C.E. Hubb.
Microchloa caffra Nees
Miscanthus capensis (Nees) Anderss.
Oropetium capense Stapf
Panicum coloratum L.
P. deustum Thunb.
P. maximum Jacq.
P. schinzii Hack.
P. stapfianum Fourc.
Paspalum dilatatum Poir. *
P. distichum L.
Pennisetum setaceum (Forssk.) Chiov. *
P. sphacelatum (Nees) Dur. & Schinz
Pentaschistis setifolia (Thunb.) McClean
Phragmites australis (Cav.) Steud.
P. mauritianus Kunth
Pogonarthria squarrosa (Licht.) Pilg.
Schmidtia kalahariensis Stent
S. pappophoroides Steud.
Setartaincrasseta (Hochst.) Hack.
S. lindenbergiana (Nees) Stapf
S. nigrirostris (Nees) Dur. & Schinz
S. pallide-fusca (Schumach.) Stapf & C.E. Hubb.
S. sphacelata (Schumach.) Moss
S. verticillata (L) Beauv.
Sorghum bicolor (L.) Moench
S. halepense (L.) Pers. *
Sporobolus discoporus Nees
Sporobolus cf. festivus A. Rich.
S. fimbriatus (Trin.) Nees var. fimbriatus
S. ioclados (Trin.) Nees
339
S. ludwigii Hochst.
S. tenellus (Spreng.) Kunth
S. virginicus (L.) Kunth
Stlpagrostis brevifolia (Nees) De Winter
S. ciliata (Desf.) De Winter
S. namaquensis (Nees) De Winter
S. obtusa (DeL) Nees
S. uniplurnis (Licht.) De Winter
Tetrachne dregei Nees
Themeda triandra Forssk.
Trachypogon spicatus (L. f.) Kuntze
Tragus berteronianus Schuldt
T. koelerioides Aschers.
T. racemosus (L.) All.
Trichoneura grandiglumis (Nees) Ekman
Triraphis andropogonoides (Steud.) PhilI.
Tristachya leucothrix Nees
Urochloa panicoides Beauv.
Potamogetonaceae
Potamogeton pusillus L.
Typhaceae
Typha capensis (Rohrb.) N.E. Br.
DICOTYLEDONAE
Acanthaceae
Barleria irritans Nees
340
B. macrostegia Nees
B. rigida Nees
Blepharis diversispina (Nees) C.B. Cl.
B. inteqrifolia (L.f.) E. Mey.
B. villosa (Nees) C.B. Cl.
Crabbea acaulis N.E. Br.
Justicia cuneata Vahl
J. protracta (Nees) T. Anders.
Monechma divaricatum (Nees) C.B. Cl.
M. incanum (Nees) C.B. Cl.
Aizoaceae
Corbichonia decumbens (Forssk.) Exell
Galenia africana L.
G. sarcophylla Fenzl
Hypertelis salsoloides (Burch.) Adamson
Limeum aethiopicum Burm.
L. sulcatum (Klotzsch) Hutch.
Plinthus cryptocarpus Fenzl
P. karooicus Verdoorn
Psammotropha mucronata (Thunb.) Fenzl
Tetragonia arbuscula Fenzl
Amaranthaceae
Achyranthes aspera L.
Alternanthera nodiflora R. Br. *
A. pungens H.B.K. *
A. repens (L.) Kuntze
A. sessilis (L.) DC. *
Amaranthus caudatus lo *
A. hybrid us lo *
A. thunbergii Moq.
341
Centrostachys aquatica (R. Br.) Wall. ex Moq.
Guilleminea densa (Willd.) Moq.
Kyphocarpa angustifolia (Moq.) Lopr.
Pupalia lappacea (L) Juss.
Sericorema remotiflora (Hook.f.) Lopr.
Anacardiaceae
Rhus burchellii Sond. ex Eng!.
R. ciliata Licht. ex Schuldt
R. dentata Thunb.
R. divaricata Eck!. & Zeyh.
R. dregeana Sond.
R. erosa Thunb.
R. lancea L.f.
R. pendulina Jacq.
Rhus pyroides Burch. var. gracilis (Eng!.) Burtt Davy
Rhus pyroides Burch. var. pyroides
Schinus molle L. *
Apiaceae
Berula erecta (Hudson) Cov. subsp. thunbergii (D.C.) B.L. Burtt
Chamarea capensis (Thunb.) Eck!. & Zeyh.
Conium chaerophylloides (Thunb.) Sond.
Deverra denudata (Viv.) Pfisterer & Pod!.
Heteromorpha trifoliata (Wend!.) Eckl. & Zeyh.
Peucedanum capense (Thunb.) Sond.
Apocynaceae
Pachypodium succulentum (L.f.) Sweet
342
Araliaceae
Cussonia paniculata Eckt. et Zeyh.
Asclepiadaceae
Asclepias crispa Berg
A. fruticosa L.
Hoodia gordonii (Mass.) Sweet ex Decne.
Microloma armatum (Thunb.) Schltr.
Orbeopsis lutea (N.E. Br.) Leach
Pentarrhinum insipidum E. Mey.
Riocreuxia torulosa Decne.
,Sarcostemma viminale (L.) R. Br.
Schizoglossum capitatum Schltr.
S. linifolium Schltr.
Stapelia grandiflora Mass.
Stenostelma capense Schltr.
Asteraceae
Arctotis arctotoides (Lf.) O. Hoffm.
A. venusta T. Nort.
Artemisia afra Jacq. ex Willd.
Athrixia angustissima DC.
Berkheya discolor (DC.) O. Hoffm. & Muschl.
B. onopordifolia (DC.) O. Hoffm. ex Burtt Davy
B. pinnatifida (Thunb.) TheII.
B. setifera DC.
Bidens bipinnata L. "
B. formosa L. *
B. pilosa L. "
Chrysocoma cillata L.
Cichorium intybus L. "
r
343
Cineraria aspera Thunb.
C. lobata l 'Hérit.
C. Iyrata DC.
Cirsium vulgare (Savi) Ten. *
Conyza bonariensis (l.) Cronq. *
C. podocephala DC.
Cotula anthemoides l.
Denekia capensis Thunb.
Dicoma anomala Sond.
D. macrocephala DC.
Dimorphotheca cuneata (Thunb.) Less.
D. zeyheri Sond.
Epaltes gariepina (DC.) Steets
Eriocephalus aspalathoides DC.
E. ericoides (l.f.) Druce
E. pubescens DC.
E. spinescens Burch.
Euryops annae Phill.
E. empetrifolius DC.
E. laterifloris (l.f.) DC.
E. multifidus (Thunb.) DC.
Felicia filifolia (Vent.) Burtt Davy
F. flanaganii H. Bol.
F. muricata (Thunb.) Neés
Flaveria bidentis (l.) Kuntze *
Garuleum pinnatifidum (Thunb.) DC.
Gazania krebsiana Less.
Geigeria espera Harv.
G. filifolia Mattf.
G. ornativa O. Hoffm.
Gerbera piloselloides (l.) Cass.
G. viridifolia (DC.) Sch. Bip.
Haplocarpa scaposa Harv.
Helichrysum appendiculatum (l.f.) Less.
H. argyrosphaerum DC.
H. asperum (Thunb.) Hilliard & Burtt .
344
H. caespititium (DC.) Harv.
H. callicomum Harv.
H. cerastioides DC.
H. dregeanum Sond. & Harv.
H. erubescens Hilliard
H. lineare DC.
H. longifolium DC.
H. lucilioides Less.
H. niveum (L.) Less.
H. nudifolium (L.) Less.
H. pentzioides Less.
H. pilosellum (L.f.) Less.
H. rosum (Berg.) Less.
H. rugulosum Less.
H. zeyheri Less.
Helichrysum sp. (Malan 998, BFLU)
Hertia ciliata (Harv.) Kuntze
H. pallens Less.
Ifloga paronychioides (DC.) Fenzl
Kleinia longifolia DC.
Lactuca capensis Thunb.
L. dregeana DC.
L. serriola L.
Nestlera conferta DC.
Nidorella auriculata DC.
N. resedifolia DC.
Nolletia arenosa O. Hoffm.
N. ciliaris (DC.) Steetz
Osteospermi.Jm leptolobum (Harv.) T. Norl.
O. muricatum E. Mey. ex DC.
O. scariosum DC.
O. spinescens Thunb.
Pegolettia retrofracta (Thunb.) Kies
Pentzia calcarea Kies
P. globosa Less.
P. incana (Thunb.) Kuntze
345
P. sphaerocephala DC.
P. spinescens less.
P. viridis Kies
Phymaspermum aciculare (E. Mey. ex Harv.) Benth. & Hook. ex Jackson
P. parvifolium (DC.) Benth. & Hook. ex Jackson
Pseudognaphalium luteo-album (L) Hillard & Burtt
P. oligandrum (DC.) Hillard & Burtt
P. undulatum (L) Hillard & Burtt
Pteronia glauca Thunb.
P. incana (Burm.) DC.
P. sordida N.E. Br.
Pteronia sp. (Malan 587, BFLU)
Pterothrix spinescens DC.
Pulicaria scabra (Thunb.) Druce
Rhynchopsidium pumilum (L.f.) DC.
Rosenia humilis (Less.) Bremner
Schistostephium crataegifolium (DC.) Fenzl ex Harv.
Schkuhria pinnata (lam.) Cabr. *
Senecio affinis DC.
S. burchellii DC.
S. consanguineus DC.
S. coronatus (Thunb.' Harv.
S. erubescens Ait.
S. hastatus lo
S. hieracioldes DC.
S. inaequidens DC.
S. inornatus DC.
S. isatideus DC.
S. latifolius DC.
S. radicans (Lf.) Sch. Bip.
S. retrorsus DC.
Sonchus hypochoeridea lo
S. oJeraceus lo
Stoebe plurnosa (lo) Thunb.
S. vulgaris Levyns
Syncarpha argyropsis (DC.) B. Nord.
346
Tagetes minuta L. *
Tarchonanthus camphoratus L.
Tragopogon dubius Scop. *
Vernonia capertsis (Houtt.) Druce
Xanthium spinosum L. *
X. strumarium L. *
Zinnia peruviana (L.) L. *
Bignoniaceae
Rhigozum obovatum Burch.
R. trichotomum Burch.
Boraginaceae
Anchusa capensis Thunb.
Ehretia rigida (Thunb.) Druce
Heliotropium curassavicum L.
H. lineare (A. DC.) C.H. WA.
H. zeylanicum (Burm. f.) Lam.
Lappula squarrosa (L.) Dumort.
Lithospermum cinereum DC.
Brassicaceae
Heliophila carnosa Steud.
H. suavissima Burch. ex DC.
Lepidium africanum (Burm. f.) DC.
Sisymbrium capense Thunb.
S. thellungii a.E. Scutz
347
Cactaceae
Cereus cabrera Mill. *
Opuntia ficus-indica (L.) Mill. *
O. imbricata (Haw.) DC. *
O. vulgaris Mill. *
Opuntia sp, * (Malan 392, BFLU)
Pseudocactus sp. * (Malan 268, BFLU)
Caesalpineaceae
Senna italica Mill. *
Carripanulaceae
Lightfootia albens Spreng. ex A. DC.
L. denticulata (Burch.) Sond.
L. nodosa Buek
Lobelia erinus L.
L. thermalis Thunb.
Wahlenbergia androsacea A. DC.
W. denticulata (Burch.) A. DC.
W. undulata (L.f.) A. DC.
Capparaceae
Boscia albitrunca Schinz
Cadaba aphylla (Thunb.) Wild
Cleome angustifolia Forssk.
348
Caryophyllaceae
Dianthus "basuticus Burtt Davy
Polycarpon tetraphyllum L. f.
Silene undulata Ait.
Celastraceae
Maytenus heterophylla (Eck!. & Zeyh.) N.K.B. Robson
M. polyacantha (Sond.) Marais
Chenopodiaceae
Atriplex erosa BrGckner & Verdoorn
A. nummularia Lindl. *
A. semibaccata R. Br.
Chenopodium album L. *
C. ambrosioides L. *
C. cristatum F. Mull.
C. murale L *
Salsola calluna Fenzl ex C.H. Wr.
S. glabrescens Burtt Davy
S. kali L.
S. rabieana Verdoorn
Suaeda fruticosa (L.) Forssk.
Clusiaceae
Hypericum aethiopicum Thunb.
Convolvulaceae
Convolvulus arvensis L. *
349
C. boedeckerianus Peter
C. sagittatus Thunb.
Ipomoea bathycolpos Hallier f.
Merremia vsrecunda Rendie
Turbina oblongata (E. Mey. ex Choisy) A. Meeuse
T. oenotheroides (L.f.) A. Meeuse
Crassulaceae
Adromischus triflorus (L.f.) Berger
A. trigynus (Burch) V. Polln.
Cotyledon orbiculata L.
Crassula capitella Thunb.
C. corallina Thunb.
C. dependens H. Bol.
C. exilis Harv.
C. lanceolata (Eck & Zeyh.) End!. ex Walp.
C. rnuscosa L. var. muscosa
.C. natans Thunb.
·C. nudicaulis L.
C. orbicularis L.
C. sarcocaulis Eck. & Zeyh.
C. setulosa Harv. var. setulosa
. Kalanchoe paniculata Harv.
K. rotundifolia (Haw.) Haw.
K. thyrsiflora Harv.
Cucurbitaceae
Acanthosicyos naudinianus Welw. ex Hook. f.
Coccinia hirtella Cogn.
C. sessilifolia (Sond.) Cogn.
Cucumis myriocarpus Naud.
Kedrostis africana (L.) Cogn.
350
Dipsacaceae
Scabiosa columbaria L.
Ebenaceae
Diospyros austro-africana De Winter
D. Iycioides Desf.
Euclea coriacea A. DC.
E. crispa (Thunb.) Guerke subsp. crispa
E. crispa (Thunb.) Guerke subsp. ovata (Burch.) F. White
Euphorbiaceae
Clutia pulchella l.
Chamaesyce inaequilatera (Sond.) Sojak
C. prostrata (Ait.) Small *
Euphorbia aequoris N.E. Br.
.E. caterviflora N.E. Br.
E. clavarioides Boiss.
E. mauritanica l.
E. rectirama N.E. Br.
E. striata Thunb.
Phyllanthus burchellii MOll
P. maderaspatensis L.
P. parvulus Sond.
Fabaceae
Argyrolobium lanceolatum Eckl. & Zeyh.
A. pauciflorum Eck!. & Zeyh.
Crotalaria distans Benth.
C. eremicola Bak. f.
351
Cullen obtusifolia (DC.) C. H. Stirton
Dolichos linearis E. Mey.
Elephantorrhiza elephantina (Burch.) Skeels
Gleditsia triacanthos L. *
Indigofera alternans DC.
I. cryptantha Benth. ex Harv.
I. nigromontana Eck!. & Zeyh.
I. rhytidocarpa Benth. ex Harv.
I. sessilifolia DC.
I. setiflora Balk.
Indigofera sp. (Malan 315, BFLU)
Lessertia annutaris Harv.
L. cf. depressa Harv.
L. pauciflora Harv.
Lotononis calycina (E. Mey.) Benth.
L. taxa Eckl. & Zeyh.
L. listii PoihilI
L. tenelIa Eckl. & Zeyh.
Medicago laciniata (L.) Mill.
M. polymorpha L.
M. sativa L. *
Melolobium calycinum Benth.
M. candicans (E. Mey) Eck. & Zey.
M. rnlcrophvllurn (L.F.) Eck!. & Zeyh.
Otholobium prodiens C.H. Stirton
Prosopis chilensis (Mo!.) Stuntz *
P. velutina Wooton *
Rhynchosia caribaea (Jacq.l DC.
A. confusa Burtt Davy
A. nervosa Benth. & Harv.
A. totta (Thunb.) DC.
Sutherlandia frutescens (L.) A. Br.
S. microphylla Burch. ex DC.
Tephrosia capensis (Jacq.) Pers.
Vicia sativa L. *
352
Gentianaceae
Sebaea filiformis Schinz
S. leiostyla Gilg
Geraniaceae
Monsonia angustifolia E. Mey. ex A. Rich.
Pelargonium abrotanifolium (L.f.) Jacq.
P. alchemilloides (L.J L'Hérit.
P. aridum R.A. Dyer
P. myrrhifolium (L.) L'Hérit
P. tragacanthoides Burch.
Sarcocaulon salmoniflorum Moffett·
lIIecebraceae
Pollichia campestris Ait.
Lamiaceae
Ajuga ophrydis Burch. ex Benth ..
Becium angustifolium (Benth.) N.E. Br.
Leonotis ocymifolia (Burm. f.) Iwarsson
Leucas capensis (Benth.) Eng!.
L. martinicensis (Jacq.) R. Br.
Mentha longifolia (L) Huds.
Salvia disermas L.
S. namaensis Schinz
S. repens Burch. ex Benth.
S. runcinata L.f.
S. stenophylla Burch.
S. verbenaca L.
353
Stachys burchelliana Launert
S. hyssopoides Burch. ex Benth.
S. rugosa Ait.
Teucrium trifidum Retz.
Linaceae
Linum thunbergii Eckl. & Zeyh.
loganiaceae
Gomphostigma virgatum (Lf.) Baill.
Buddleja saligna Willd.
B. salviifolia (L.) Lam.
Malvaceae
Abutilon austro-africanum Hochr.
A. grandifolium (Willd.) Sweet
A. piloso-cinereum A. Meeuse
A. pycnodon Hochr.
Hibiscus aethiopicus L.
H. lunarifolius Willd.
H. malacospermus (Turcz.) E. Mey. ex Harv.
H. marlothianus K. Schum.
H. microcarpus Garcke
H. pusillus Thunb.
H. trionum L.
Pavonia burehetlil (DC.) R.A. Dyer
Sphaeralcea bonariensis (Cav.) Griseb. *
Sida dregei Burtt Davy
Radyera urens (L.f.) Bullock
354
Meliaceae
Melia azederach L. *
Melianthaceae
Melianthus comosus Vahl
Menispermaceae
Antizoma angustifolia (Burch.) Miers ex Harv.
Mesembryanthemaceae
Chasmatophyllum musculinum (Haw.) Dinter & Schwant.
Delosperma cooperi (Hook.f.) L. Bol.
D. mahonii (N.E. Br.) N.E. Br.
D. pcttsii (L. Bol) L. Bol.
Delosperrna sp. (Malan 119, BFLU)
Drosanthemum sp. (Malan 1123, BFLU)
Eberlanzia spinosa (L.) Schwant.
Mestoklema arboriforme (Burch.) N.E. Br. ex Glen
M. tuberosum (L.) N.E. Br. ex Glen
Nananthus vittatus (N.E. Br.) Schwant.
Neohenricia sibbettii (L. Bol:) l. Bol.
Psilocaulon absimile N.E. Br.
P. junceum (Haw.) Schwant.
Stomatium mustellinum (Salm-Dyck) Schwant.
Ruschia hamata (L. BoL) senwant.
R. rigens L. Bol.
A. rigida (Haw.) Schwant.
Ruschia sp. (Malan 766, BFLU)
Trichodiadema barbatum (l.) Schwant.
355
T. pomeridianum L. Bol.
Mimosaceae
Acacia erioloba E. Mey.
A. hebeclada DC.
A. mellifera (Vahl) Benth.
A. karroo Hayne
A. tortuis (Forssk.) Hayne subsp. heteracaritha
Myrsinaceae
Myrsine africana L.
Myrtaceae
Eucalyptus sp. * (Malan 68, BFLU)
Nyctaginaceae
Commicarpus pentandrus (Burch.) Heimert
Phaeoptilum spinosum Radik.
Ochnaceae
Ochna serrulata (Hochst.) Walp.
Oleaceae
Menodora africana Hook.
Olea europaea subsp. africana (MilL) P.S. Green
356
Onagraceae
Oenothera biennis L. *
O. indecora Cambess. *
O. rosea L'Herit. ex Ait. *
O. stricta Ledeb. ex Link *
O. tetraptera Cav. *
Oenothera sp. * (Malan 221 t BFLU)
Oxalidaceae
Oxalis corniculata L. *
O. depressa Eck!. & Zeyh.
Papaveraceae
Argemone mexicana L. *
A. ochroleuca Sweet subsp. ochroleuca *.
Papaver aculeatum Thunb.
Pedaliaceae
Harpagophytum procumbens (Burch.) DC. ex Meissn.
Sesamum capense Burm. f.
S. triphyllum Welw.
Penaeaceae
Saltera sarcocolla (L.) Bullock
357
Periplocaceae
Raphionacme hirsuta (E. Mey.) R.A. Dyer ex Phill.
Phytolacaceae
Gisekia pharnacioides L.
Plantaginaceae
Plantago lanceolata L. *
Polygalaceae
Pofygala amatymbica Eckl. & Zeyh.
P. asbestina Burch.
P. ephedroides Burch.
P. hottentotta Presl
P. leptophylta Burch.
P. rehmannii Chod.
P. uncinata E. Mey. ex Meisn.
Polygonaceae
Persicaria attenuata (R. Br.) Sojak
P. serrulata (Lag.) Webb & MOQ.
Polygonum aviculare L. *
P. hystriculum Schuster
P. kitaibeJianum Sadier *
Rumex acetoselIa L.
R. crispus L. *
R. lanceolatus Thunb.
358
Portulacaceae
Anacampseros filamentosa (Haw.) Sims
A. lanceolata (Harv.) Sweet
A. telephiastrum DC.
A. truncata V. PoeIIn.
A. ustulata E. Mey. ex Sond.
Portulaca oleracea L. *
Talinum caffrum (Thunb.) Eck!. & Zeyh.
Ranunculaceae
Clematis brachiata Thunb.
Ranunculus multifidus Forssk.
Resedaceae
Oligomeris sp. (Malan 148, BFLU)
Rhamnaceae
Rhamnus prinoides L'Hérit.
Ziziphus mucronata Willd.
Rubiaceae
Anthospermum herbaceum L.F.
A. rigidum Eckl, & Zeyh .:
A. spathulatum Spreng.
Kohautia amatymbica Eckl. & Zeyh.
359
Rosaceae
Althaea rosea L. *
Cliffortia nitidula (Enbl.) A.E. & Th. Fries Jr.
C. paucistaminea Weim.
Cotoneaster sp. * (Malan 89, BFLU)
Leucosidea sericea Eckl. & Zeyh.
Prunus persica (L.) Batsch *
Pyracantha crenulata (D. Don) M.J. Roem. *
Rosa eglanteria L. *
Rubiaceae
Nenax microphylla (Sond.) Salter
Rubia horrid a (Thunb.) Puff
A. petiolaris DC.
Salicaceae
Populus canescens (Ait.) J. E. Sm. *
P. nigra L. *
Salix babylonica L. *
S. mucronata Thunb.
Santalaceae
Osyris lanceolata Hochst. & Steud.
Thesium hystrix A.W. Hill
T. spartioides A.W. Hili
T. strictum Berg.
Thesium sp. (Malan 280, BFLU)
360
Scrophulariaceae
Alectra orobanchoides Benth.
Aptosimum albomarginatum Marloth & Engl.
A. indivisum Burch. ex Benth.
A. marlothii (EngJ.) Hiern
A. procumbens (Lehm.) Steud.
A. spineseens (Thunb.) Weber
Nemesia albiflora N.E. Br.
N. fruticans (Thunb.) Benth.
Peliostomum leucorrhizum E. Mey.
Striga bilabiata (Thunb.) Kuntze
S. etegans Benth.
Sutera albiftora Verdoorn
S. argentea (Lf.) Hiern
S. atropurpurea (Benth.) Hiern
S. aurantiaca (Burch.) Hiern
S. caurutea (L.f.) Hiern
S. crassicaulis (Benth.) Hiern
S. fiticaulis (Benth.) Hiern
S. halimifolia (Benth.) Kuntze
S. kraussiana (Bernh. ex Krauss) Hiern
S. pinnatifida (Benth.) Kuntze
Veronica anagallis-aquatica L.
Selaginaceae
Hebenstretia integrifolia L.
Selago albida Choisy
S. gatpinii Schttr.
S. speciosa Rotfe
Walafrida densiflora (Rotfe) Rotfe
W. geniculata (L.f.) Rotfe
W. saxatitis (E. Mey.) Rotfe
361
Solanaceae
Datura ferox L. *
Lycium cinereum Thunb.
L. hirsutum Dun.
L. horridum Thunb.
L. pilifolium C.H. Wr.
Nicotiana glauca A.C. Grah. *
Nierembergia caerulea Hook. *'
Physalis viscosa L. *
Solanum coccineum Jacq.
S. eleagnifolium Cav. *'
S. incanum L. *'
S. linnaeanum Hepper & Jaeger
S. panduriforme E. Mey. *
S. retroflexum Dun. *'
S. rostratum Dun. *'
S. supinum Dun. *'
Withania somnifera (L.) Dun.
Sterculiaceae
Hermannia amoena Dinter ex M. Holzhammer
H. bryoniifolia Burch.
H. coccocarpa (Eckl. & Zeyh.) Kuntze
H. comosa Burch. ex DC.
H. cuneifolia Jacq.
H. depressa N.E. Br.
H. erodioides (Burch. ex DC.) Kuntze
H. geniculata Eckl, & Zeyh.
H. linearifolia Harv.
H. modesta (Ehrenb.) Mast.
H. parvlflora Eckl. & Zeyh.
H. pulverata Andr.
H. quartiniana A. Rich.
362
H. spinosa E. Mey. ex Harv.
H. tomentosa (Turcz.) Schinz ex Engl.
H. vestita Thunb.
Hermannia sp. (Malan 595, BFLU)
Melhania prostrata DC.
M. rehmannii Szyszyl.
Thymelaeaceae
Gnidia capitata L.f.
G. microcephala Meisn.
G. polycephala (C.A. Mey.) Gilg
Passerina montana Thoday
Tiliaceae
Corchorus asplenifolius Burch.
Grewia flava DC.
G. occidentalls L.
Ulmaceae
Celtis africana Burm. f.
Urticaceae
Forsskaolea viridis Ehrenb. ex Webb
Urtica dioica L. *
Vahliaceae
Vahlia capensis (L.f.) Thunb.
363
Verbenaceae
Lantana rugosa Thunb.
Phyla nodiflora (L.) Greene
Plexipus pinnatifidus (L.f.) R. Fernandes
Verbena bonariensis L. *
V. officinalis L. *
V. tenuisecta Briq. *
Viscaceae
Viscum rotundifolium L.f.
Vitaceae
Cyphostemma hereroense (Schinz) Descoings ex Wild & Drum.
Zygophyllaceae
Tribulus terrestris L.
Zygophyllum cylindrifolium Schinz
Z. gilfillanii N.E. Br.
Z. incrustatum E. Mey. ex Sond.
Z. macrocarpon Retief
Z. microphyllum L.f.
Z. simplex L.
364
Table 1: The relationship between the number of families, genera and
species.
Families Genera Species
Bryopbyta 1 1 1
Pteridophyta 5 6 9
Gymnospermae 1 1 1
Monocotyled.onae 16 94 195
Dicotyledonae 75 275 568
TOTAL 98 377 774
Table 2: Most prominent families (represented by 10 and more species).
Family Genera Species
Asteraceae 55 128
Poaceae 52 109
Fabaceae 17 39
Cyperaceae 10 24
Scrophulariaceae 7 22
Mesembryenthemaceae 11 20
Sterculiaceae 2 19
Crassulaceae 4 17
Solanaceae 7 17
Lamiaceae 8 16
Malvaceae 6 15
Amaranthaceae 8 13
Asclepiadaceae 10 12
Chenopodiaceae 4 12
Euphorbiaceae 4 12
Hyacinthaceae 8 12
Acanthaceae 5 11
Anacardiaceae 2 11
Aizoaceae 7 10
365
Table 2: (Continue)
Asparagaceae 1 10
Asphodelaceae 4 10
Table 3: Genera represented by 5 and more species.
Genera Species
Helichrysum (Asteraceae) 19
Eragrostis (poaceae) 17
Hermannia (StercUliaceae) 17
Senecio (Asteraceae) 13
Crassula (Crassulaceae) 11
Cyperus (Cyperaceae) 11
Protasparagus (Asparagaceae) 10
Rhus (Anacardiaceae) 10
Sutera (Scrophulariaceae) 10
Solanum (Solanaceae) 8
Hibiscus (Malvaceae) 7
Indigofera (Fabaceae) 7
Polygala (Polygalaceae)· 7
Sporobolus (Poaceae) 7
Aristida (Poaceae) 6
Euphorbia (Buphorbiaceae) 6
Oenothera (Onagraceae) 6
Pentzia (Asteraceae) 6
Salvia (Lamiaceae) 6
Setaria (Poaceae) 6
Zygophyllum (Zygophyllaceae) 6
Acacia (Mimosaceae) 5
Aloe (Asphodelaceae) 5
Anacampseros (Portulacaceae) 5
Aptosimum (Scrophulariaceae) 5
Panicum (Poaceae) 5
Pelargonium {Geraniaceae} 5
Stipagrostis (Poaceae) 5
366
Table 4: List of naturalized exotic species (Arnold & De Wet 1993).
Alternanthera nodiflora Nierembergia caerulea
A. pungens Oenothera biennis
A. sessilis o. indecora
Althaea rosea o. rosea
Amaranthus caudatus o. stricta
A. hybridus o. tetraptera
Argemone mexicana Oenothera sp.
A. ochroleuca Opuntia ficus-indica
Arundo donax o. imbricata
Atriplex nummularia o. vulgaris
Azolla filiculoides Opuntia sp.
Bidens bipinnata Oxalis corniculata
B. formosa Paspalum dilatatum
B. pilosa Pennisetum setaceum
Bromus catharticus Physalis viscosa
Cereus cabrera Plantago lanceolata
Chamaesyce prostrata Polygonum aviculare
Chenopodium album P. kitaibelianum
C. ambrosioides Populus canescens
C. murale P. nigra
Cichorium intybus Portulaca oleracea
Cirsium vulgare Prosopis chilensis
Convolvulus arvensis P. velutina
Conyza bonariensis Prunus persica
Cotoneaster sp. Pseudocactus sp.
Cupressus torulosa Pyracantha crenulata
Cyperus eragrostis Rosa eglanteria
Datura ferox Rumex crispus
Eucalyptus sp. Salix babylonica
Flaveria bidentis Schinus molle
Gleditsia triacanthos Schkuhria pinnata
Medicago sativa Senna italica
Melia azederach Solanum coccineum
Nicotiana glauca S. eleagnifolium
367
Table 4: (Continue)
Solanum incanum Urtica dioica
S. panduriforme Verbena bonariensis
S. retroflexum V. officinalis
S. rostratum V. tenuisecta
S. supinum Vicia sativa
Sorghum halepense Xanthium spinosum
Sphaeralcea bonariensis X. strumarium
Tagetes minuta Zinnia peruviana
Tragopogon dubius
368
CHAPTER 13
Vegetation ecology of the southern Free State
Vegetation ecology of the southern Free State: General discussion and
concluding remarks
369
CHAPTER 13
GENERAL DISCUSSION AND CONCLUDING REMARKS
13.1 GENERAL DISCUSSION
The presented detailed identification, description, classification and
ecological interpretation of the plant communities encountered in the
southern Free State contribute substantially towards the knowledge of the
vegetation of the study area and the Grassland Biome of southern Africa.
The Braun-Blanquet approach was used to floristically define the plant
communities. The subsequent Braun-Blanquet classifications of the different
vegetation units and- synecological synthesis of the vegetation on the study
area provide an important classiflcatorv and managerial reference framework
of the major vegetation units and vegetation types in the southern Free
State.
The two-step classification method, a new approach to investigate,
compare and classify large phytosociological data sets from various sources
and from large geographical regions, proved to be successful, not only to
effectively bring together all related plant communities from different
regions, or different studies, but especially to identify phytosociological
classes as the highest syntaxonomical rank.
The relatively low and erratic rainfall of the study area, especially in the
western parts, does not favour agronomy, although many farmers have
ploughed and otanted maize and/or other crops in good rainfall years.
Mismanagement of natural pasture (e.g.overgrazing) in many parts of the
study area contributed greatly to the degradation of natural pasture.
Grazing during the active growth stages of a plant results in vegetative
damage and destruction of plant material. This can lead, in severe cases, to
the complete absence of ecologically important species and thus seriously
affects the whole environment by the invasion of ecologically less important
species. This is clearly illustrated in the presence of species such as
--------------------------------------------------------------------- J
370
Asclepias truticose, Berkheya onoporditolie, B. pinnatifida, Chenopodium
album, the Karoo encroacher Chrysocoma ciliata, Hertia pal/ens, Lveiurn
cinereum, Pentzia globosa, Protasparagus tericinus, P. suaveolens, Salvia
verbenaca, Talinum caffrum, Tribulus terrestris, Walafrida saxatilis, as well
as the grasses Aristida congesta, Chloris virgata, Eragrostis curvule, E.
lehmanniana, E. obtusa and Tragus berteronianus (See Chapter 11).
According to Hoffman et al. (1990) an increase in grass basal cover may
negatively influence shrub basal cover. According to them, a large increase
in summer rain, relative to the long-term mean, would result in an
associated increase in the percentage change in grass basal cover. It should,
however, be kept in mind that various other environmental factors, such as
light intensity, temperature etc. are also involved in vegetation changes. A
further aspect is to incorporate different stock ratios to attempt to utilize a
wider spectrum of plants which could lead to better unit area utilization,
favourable grazing capacities, and consequently higher economic returns.
All over the province one finds examples of good, conservation-
conscious farmers whose use of the correct number of animals and the
healthy rotation of stocks between camps, promote veld recovery.
Unfortunately, the contrary has also been widely observed. According to
Potgieter et al. (1995) the advantage of good veld management lies in the
correct number of animals according to the grazing capacity. An increase in
stock numbers will have a severe and adverse effect on the veld.
Stratification was based on land type, topographical posttien (plateau or
slope), aspect and geology. The slopes were stratified according to crests,
scarps, midslopes, footslopes and valley bottoms or flood plains which is in
accordance with the stratification used by Fuls (1993).
Bezuidenhout (1993), Coetzee (1993), Eckhardt (1993) and Kooij (1993)
also used land types as a first stratification.
Seven major communities were identified and can easily be recognized in
the study area.
371
The significant plant community variation in an area which is generally
regarded as homogeneous, concomitant with an unique set of environmental
conditions prevalent with each plant community, have important
management implications (Fuls 1993). These results can be used in future
ecologically sound research, management and conservation strategies. It
should also be used by conservationists and agriculturists for optimal land
use planning. It is also possible that the farmer at farm level scale could
make use of these results.
Two biomes were tdentitled in the study area, namely the Grassland and
Nama-Karoo Biomes. The mean annual rainfall in the Grassland Biome in the
study area varies between 500 and 700 mm per annum while the Nama-
Karoo Biome mainly falls within the 200-400 and 400-600 mm per annum
rainfall intervals.
The vegetation of the Grassland Biome is physiognomically monolithic
and is characterized by strong dominance of hemicryptophytes of the
Poaceae. Canopy cover is moisture dependent and decreases with mean
annual rainfall. Grazing has a decisive influence on canopy structure
(Rutherford & Westfall 1994).
The vegetation of the Grassland Biome follows a rainfall gradient which
generally corresponds to the relative contributions to the plant cover by
"sweet" and "sour" grasses.. Probably the most noteworthy species with
wide distribution in the Grassland Biorne is Themeda triandra Forssk.
The number of rare plants in the Grassland Biome is not particularly
large, but increases in the wetter areas and mainly includes non-graminoid
plants, especially geophytes (Hilton-Taylor 1996).
The vegetation of the Nama-Karoo Biome is dominated by chamaephytes
and hemicryptophytes and can be described as a grassy, dwarf shrubland
(Edwards 1983). The hemicryptophytes of the biome are mainly C4
graminoids (Vogel et al. 1978). Plant species diversity and number of rare
and endangered species in the biome are relatively low (Hall et al. 1980).
Succession of plant composition is usually taken to start after disturbance
372
by overgrazing. The usual progression, given a significant reduction in
grazing pressure and a suitable distribution of rainfall (Vorster & Roux
1983), is a steady increase in hemicryptophyte cover and a more variable
decrease in chamaephyte cover.
Acocks (1988) identified six veld types in the southern Free State. On a
1: 1 500 000 scale Acocks's veld types are relatively accurate in the
southern Free State, but refinement of the boundaries between the different
veld types is necessary. These veld types, however, can still be used as a
basis for future research.
The final synthesis of the vegetation of the southern Free State resulted
in the identification of 16 phytosociological classes. These classes are also
easily distinguishable in the veld. Although some floristic relationships do
exist between the different classes, each class has its own set of
environmental and ecological attributes. The results of the ordinations
(DECORANA) (Hill 1979) indicate the floristic relationships amongst the
vegetation units. It was possible to relate the vegetation units to certain
environmental variables and often clear gradients could be recognized. This
could be ascribed to the relatively low to intermediate rainfall of the study
area where the importance of terrain and soil types, soil depth, clay content,
drainage and rockiness of the soil surface is emphasized (Bezuidenhout
1993). Higher rainfall to the south-eastern parts causes the influence of
these environmental factors to be less prominent (Eckhardt 1993 and Fuls
1993). The large impact of habitat disturbance in the study area by means _
of utilization is evident throughout the whole southern Free State.
13.2 CONCLUDING REMARKS
The aims set forth for this study were satisfactorily achieved.
The aims as put forward in Chapter 1 of this dissertation were threefold:
(1) To identify, classify, describe and ecologically interpret the different
plant communities of the southern Free State,
373
(2) to compile a synecological synthesis of the southern Free State, and
(3) to concur with the goals of the Grassland Biome Project namely to
identify, describe and determine the location of major vegetation types
within the Grassland Biome (Mentis & Huntley 1982).
The classification, description and ecological interpretations of the
vegetation and associated habitats in the southern Free State should form
the basis for future conservation and management strategies. A major future
research priority which flows from this study is a refinement of the
vegetation classes identified in the study area. Such a refinement, followed
by a formal syntaxonomical classification of all the syntaxa, should
complement the Grassland Biome Project.
In conclusion, natural veld remains the cheapest form of forage for
farmers, and everything possible must be done to keep it at its optimum
condition by means of the application of the correct number of animals and
the correct rest and grazing periods. This should always be the basis of any
forage flow programme on any farm (Potgieter et al. 1995).
374
13.3 REFERENCES
ACOCKS, J.P.H. 1988. Veld types of South Africa. 3 rd edn. Mem. bot.
Surv. S. Afr. 57: 1-146.
BEZUIDENHOUT, H. 1993. Syntaxonomy and synecology of the western
Transvaal grasslands. Unpublished Ph.D. dissertation. University of
Pretoria, Pretoria ..
COETZEE, J.P. 1993. Phytosociology of the Ba and Ib land types in the
Pretoria-Witbank-Heidelberg area. Unpublished M.Sc. thesis. University
of Pretoria, Pretoria.
ECKHARDT, H.C. 1993. A synecological study of the vegetation of the
north-eastern Orange Free State. Unpublished M.Sc. thesis. University of
Pretoria, Pretoria.
EDWARDS, D. 1983. A broad-scale structural classification of vegetation for
practical purposes. Bothalia 14: 705-712.
FULS, E.R. 1993. Vegetation ecology of the northern Orange Free State.
Unpublished Ph.D. dissertation. University of Pretoria, Pretoria.
HALL, A.V., DEW'INTER,M., DEWINTER, B., OOSTERHOUT,S.A.M. 1980.
Threatened plants of southern Africa. S. Afr. Nat. Sci. Prog. Rep. No.
45: 1-241.
HILL, M.O. 1979. DECORANA - a FORTRAN program for detrended
correspondence analysis and reciprocal averaging. Department of
Ecology and Systematics, Cornel! University, Ithaca, New York.
HILTON-TAYLOR, C. 1996. The Red Data list for southern African plants.
Strelitzia 4.
HOFFMAN, M.T. BARR, G.O. & ~OWLlNG R.M. 1990. Vegetation dynamics
in the semi-arid eastern Karoo, South Africa: the effect of seasonal
375
rainfall and competition on grass and shrub basal cover. S. Afr. J. Sci.
86: 462-463.
KOOIJ, M.S. 1990. A phytosociological survey of the vegetation of the
north-western Orange Free State. Unpublished M.Sc. thesis University of
Pretoria, Pretoria.
MENTIS, M.T. & HUNTLEY, B.J. 1982. A description of the Grassland
Biome Project. S. Afr. Nat. Sci. Prog. Rep. 62: 1-29.
POTGIETER, P.J.o(ED.), LE ROUX, P.A.L., VAN BILJON, J.J., VAN DER
RYST, C., KRIGE, S. & PRETORIUS,T. 1995. Regional overview study of
the Free State. Cornrnlssfoned by the Land and Agricultural Policy
Centre, Bloemfontein.
RUTHERFORD,M.C. & WESTFALL, R.H. 1994. Biomes of southern Africa -
an objective categorization. 2 nd edn. Mem. bot. Surv. S. Afr. 63: 1-
94.
VOGEL, J.C., FULS, A & ELLIS, R.P. 1978. The geographical distribution of
Kranz grasses in South Africa. S. Afr. J. Sci. 74: 209-215.
VORSTER, M. & ROUX, P.W. 1983. Veld of the Karoo areas. Proc. Grass/d.
Soc. Sth. Afr. 18: 18-24.
376
OPSOMMING
Plantekologie van die suidelike Vrystaat
deur
Pieter Willem Malan
Promotor: Prof. Dr. H.J.T. Venter
Mede-promotor: Dr. P.J. du Preez
in die
Departement Plantkunde & Genetika
Universiteit van die Oranje-Vrystaat
vir die graad
PHILOSOPHIAEDOCTOR (PLANTKUNDE)
Hierdie studie vorm 'n integrale deel van die oorhoofse langtermyn doeI om
'n omvattende sinekologiese sintese van die Grasveldbioom van suidelike
Afrika daar te stel. Met die aanvang van die projek was daar relatief min
inligting oor die plantegroei van die gebied bekend. Die hoofdoel van hierdie
studie was:
(1) om die plantgemeenskappe in die studiegebied te identifiseer, te
klassifiseer en ekologies te interpreteer,
(2) om 'n omvattende fitososiologiese en sinekologiese sintese van die
plantegroei van die studiegebied daar te stel, insluitende alle
fitososiologiese data ingesamel deur ander navorsers in die suidelike
Vrystaat, en
(3) om 'n bydrae te lewer omtrent die daarstelling van 'n volledige
sinekologiese sintese van die Grasveldbioom.
Die studiegebied Is in die suidelike Vrystaat geleë, beslaan 'n totale
oppervlak.te van ongeveer 27 000 km2 en word begrens deur die
377
lengtegraad 29°Suid en breedtegraad 27°00s. Dit word begrens deur die
Oranjerivier in die suide en die denkbeeldige grens tussen die Vrystaat- en
Noord-Kaap Provinsie in die weste.
Die doelwitte is bereik deur ekstensiewe fitososiologiese opnames in die
studiegebied uit te voer. Die studiegebied is gestratifiseer volgens relatiewe
homogene eenhede van faktore soos geologie, topografie (terrein vorm),
fisionomie en dominante spesies. 'n Fitososiologiese ondersoek, volgens
Braun-Blanquet prosedures asook 'n habitat opname is uitgevoer. Die data is
deur middel van die TWINSPAN- program geklassifiseer en daarna deur die
Braun-Blanquet prosedures verfyn.
Uit die 2 370 relevés wat in die suidelike Vrystaat saamgestel is, is 394
plantgemeenskappe ge·(jentifiseer,. geklassifiseer, beskryf en ekologies
genterpreteer.
Uit die omvattende fitososiologiese sintese van die 394 beskryfde
plantgemeenskappe van die suidelike Vrystaat is 16 hoofplantegroeitipes in
die studiegebied beskryf.
'n Ordeningsalgoritme (DECORANA) wat die floristiese verwantskappe
tussen die plantegroei-eenhede aandui, is gebruik om die klassifikasies aan
te vul.
Die sinekologiese sintese van die suidelike Vrystaat lewer 'n bydra tot die
uiteindelike doel, nl. om 'n volledige sinekologiese en sintaksonomiese
sintese van die Grasveldbioom in suidelike Afrika daar te stel.
378
SUMMARY
Vegetation ecology of the southern Free State
by
Pieter Willem Malan
Promoter: Prof. Dr. H.J.T. Venter
Co-promoter: Dr. P.J. du Preez
in the
Department of Botany & Genetics
University of the Orange Free State
for the degree
PHILOSOPHIAEDOCTOR (BOTANY)
This study forms an integral part of the main long-term goal to compile a
. comprehensive synecological synthesis of the vegetation of the southern
Free State.
Relatively little is known about the vegetation of the study area. The
main aim of the study was:
(1) to identify, classify and ecologically interpret the plant communities in
the study area,
(2) to compile a comprehensive phytosociologicaJ and synecological
synthesis of the vegetation of the study area, including all the
phytosociological data compiled by other researchers in the southern Free
State, and
(3) to take part in compiling a comprehensive synecological synthesis of the
Grassland Biome.
The study area is situated in the southern Free State, covers
approximately 27 000 km2 and is bounded by latitude 29° South and
379
longitude 270 East. It is bounded by the Orange River in the south and by
the imaginary boundary between the Free State and Northern Cape Province
in the west.
The aims were achieved through compiling extensive phytosociological
surveys in the study area. The study area was stratified into relative
homogeneous units of major attributes such as geology, topography (land
form), physiognomy and dominant species. A phytosociological survey
according to Braun-Blanquet procedures as weU as habitat analysis were
being done. Data were being classified through the TWINSPAN program and
then refined by Braun-Blanquet procedures.
From the 2 370 relevés compiled in the southern Free State, 394 plant
communities were identified, classified and ecologically interpreted.
16 Major vegetation units were described from the 394 described plant
communities.
An ordination algorithm (DECORANA) was used to indicate the floristic
relationships among the vegetation units and make the classifications more
interpretable.
The synecological synthesis of the vegetation of the southern Free State
plays an important role in compiling a comprehensive synecological and
syntaxonomical synthesis of the vegetation of the Grassland Biome of
southern Africa.
380
ACKNOWlEOGEMENTS
The assistance and co-operation of the following persons and organizations
are gratefully acknowledged:
* Prof. H.J.T. Venter and Dr. P.J. du Preez, my supervisors, of the
Department of Botany & Genetics of the University of the Orange Free State
for their help, guidance, comments and encouragement.
* Dr. P.A.L. le Roux of the Department of Soil Sciences of the University of
the Orange Free State for his help in interpreting the soils of the study area.
* Mr. J.C. loock of the Department of Geology for fruitful discussions on
the geology of the study area.
* Mrs. H. Kriel for her help of identification of the plant specimens.
* The Department of Environmental Affairs for funding this project.
* The Nature and Environmental Conservation Directorate of the Free State
Provincial Administration for providing plant collecting permits.
* The staff of the National Herbarium (PRE) for the identification of the
specimens.
* Special thanks to Mrs. M.S. Deutschlánder for her help with the
preparation of the phytosociological tables.
* Mr. P. Van der Merwe and Mrs. Kate Smit of the Computer Centre at the
University of the Orange Free State for his assistance with the computer
programmes.
* Mrs. A.J. Malan and Mrs. J.M. Walker for the language revision of the
manuscript.
381
* The landowners in the study area for granting permission to work on their
property.
* My family and friends for their encouragement.
IJ li
382
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