S.Afr.J.Bot., 1992,58(4): 231 - 235 231 The hydrophilic vegetation of the - - Lindley - area, northern Orange

E.R. Fuls, G.J. Bredenkamp and N. van Rooyen Department of Botany, University of Pretoria, Pretoria, 0002 Republic of

Received 23 October 1991; revised 31 March 1992

An analysis of the plant communities of the watercourses of the Vredefort - Kroonstad - Lindley - Heilbron area (northern ) is presented. Releves were compiled in 34 stratified random sample plots. A TWINSPAN classification, refined by Braun-Blanquet procedures, revealed four distinct plant communities. A hierarchical classification, description and ecological interpretation of the plant communities are presented.

'n Analise van die plantgemeenskappe van die waterbane van die Vredefort - Kroonstad - Lindley - Heilbron area (noordelike Oranje-Vrystaat) word gegee. Releves is in 34 gestratifiseerde ewekansig gekose monsterpersele saamgestel. 'n TWINSPAN-klassifikasie, verfyn deur Braun-Blanquet-prosedures, toon vier duidelik onderskeibare plantgemeenskappe. 'n Hierargiese klassifikasie, beskrywing en ekologiese interpretasie van hierdie plantgemeenskappeword aangebied.

Keywords: Braun-Blanquet classification, grassland biome, synecology, TWINSPAN

Introduction Kroonstad map (1:250 (00) (Land Type Survey Staff 1984), The northern part of the Orange Free State is one of the within the climatic climax grassland biome of southern most important agricultural regions of southern Africa, both Africa (Mentis & Huntley 1982). The area is situated in terms of intensive crop production and extensive stock between 27°11' and 28°lO'E longitude and 2rOO' and farming (Scheepers 1975; Mentis & Huntley 1982). The 28°00'S latitude (Figure 1). Towns situated in, or widespread ploughing of arable land concomitant with bordering on, the study area are Kroonstad, Heilbron, livestock grazing pressure resulted in the destruction of large portions of pristine vegetation in the area. The sensitivity of hydrophilic vegetation makes the watercourses

especially vulnerable to degradation. Increased run-off and 27', 27~30'E 28"E 270$ -+------='"77777777:7'7":''777777:7"!""'-'---,-27'S erosion, liberal use of fertilizer and pesticides within catchment areas, as well as indiscriminate utilization by livestock, are but a few aspects which contribute to water­ course degradation in the area. Since the broad vegetation classification and mapping presented by Acocks in 1953 (Acocks 1953, 1988), very little advance has been made towards a more detailed classi­ fication and description of the vegetation of the area. In 27'l30'S 2]030'$ view of the predicament of the natural vegetation of the study area, it is imperative that future land-use planning, management and conservation strategies are based on sound plant ecological principles. To facilitate optimal resource utilization in general, and to assess the conservation status of the vegetation in particular, a detailed identification,

classification and mapping of the vegetation of the region 28CS has been undertaken. The physical environment and major 27', vegetation types, the plant communities of the rocky out­ crops and the undulating grasslands of the study area are 21" described by Fuls et al. (1992a), Fuls et al. (1992b) and Fuls et al. (l992c), respectively. In this paper the plant commun­ ities and associated habitats of the watercourses of the 25' northern Orange Free State are described. This study forms f an integral part of the ultimate goal to compile a compre­ 29' N hensive syntaxonomical synthesis of the grasslands of south­ ern Africa (see also Bredenkamp at. 1989; Kooij al. Cape Provin ce o ~OO "m et et "'===='=====' 33°5 1990). 33'S 19'

Study area Figure 1 The study area (hatched) in which the hydrophylic The study area comprises the eastern pan of the 2726 vegetation of the watercourses was analysed. 232 S.-Afr.Tydskr.Plantk.,1992,58(4)

Vredefort, Lindley and . The area covers approxi­ Taxa names conform to those of Gibbs Russell et al. (1985, mately 750000 ha. The study area forms part of the High­ 1987). veld inland plateau, consists predominantly of smoothly Two-way indicator species analysis (TWINSPAN) (Hill plained or gently undulating land surfaces of the Miocene 1979) was applied to the floristic data set in order to derive age (Mentis & Huntley 1982) and is situated between 1300 a first approximation of the vegetation types of the area. m and 1700 m above sea-level. The topography comprises a Refinement of this classification was done by means of mosaic of flat, slightly undulating and undulating terrain Braun-Blanquet procedures (Bredenkamp et al. 1989; Kooij (Land Type Survey Staff 1984). Isolated hills and ridges are et al. 1990). encountered occasionally. The area covered by the water­ Results courses comprises less than 5% of the study area (Fuls et al. 1992a). The watercourses are not particularly species-rich, being Drainage of the study area is variable with the major mostly dominated by a few herb species (Table 1). A total portion thereof reasonably well-drained to well-drained. of 123 species was recorded in the 34 sample plots, with the Permanently waterlogged soils, pans and vIcis are scarce average number of species per sample plot being 21. From the final differential table, four plant communities and seasonally standing water is mostly restricted to slow­ were identified (Table 1). draining watercourses. Slow-draining streams are common A diagrammatic presentation of the hierarchical classifi­ owing to the flatness of the terrain in most parts of the study cation and associated environmental interpretation of the area. The major rivers draining the area are the Va Is River four plant communities is presented in Figure 2. and Renoster River. The main drainage is from the higher lying south-east towards the lower lying north-west. The Description of the plant communities study area forms part of the catchment area of the Vaal The floristics and associated environmental attributes for the River below the Vaal Dam. Stream incision is mostly respective plant communities (Table 1) are given below. shallow except for the Vals and Renoster Rivers and a few of their main tributaries. 1. Andropogon appendiculatus - Cyperus jastigiatus Wetland (type releve: 79) Methods The vegetation of the watercourses can be broadly classified Releves were compiled in 34 stratified random sample plots. as an Andropogon appendiculatus - Cyperus Jastigiatus Stratification was based on depth of streambed incision, Wetland (Table 1). Graminoids with a high constancy in this topography, drainage variation and land type [Bd Land Type community include Eragrostis plana, Paspalum dilatatum, / Dc Land Type (Land Type Survey Staff 1984)] . Plot sizes Cynodon dactylon, Pennisetum sphacelatum and Setaria were fixed at 100 m2 (Scheepers 1975). In each sample plot nigrirostris (species group H - Table 1). Forb species which all species were recorded, using the Braun-Blanquet cover­ are commonly encountered include Berkheya radula, Haplo­ abundance values (Mueller-Dombois & Ellenberg 1974). carpha scaposa, Cyperus longus and Mariscus congestus

Watercourses l

- Deep/intermediate - Shallow streambed streambed incision incision - Fast drainage - Slow drainage - Stagnant water - Stagnant water mostly absent often present - Streambanks dry - Stream banks moist

- Overutilized/ disturbed - Intermediate streambed incision

- Deep streambed - Intermediate incision streambed - Streambanks incision relatively dry - Streambanks - Fast run-off relative (periodic moist flash-floods)

,. '" 1.1.1 (a) 1.1.1 (b) 1.1.2 1.2 Figure 2 The hierarchical classification and associated environmental characteristics of the four plant communities. Numbers of plant communities correspond with descriptions in text. 233 S.AfrJ.Bot.. 1992. 58(4)

Table 1 Phytosociological table of the hydrophilic vegetation of the northern Orange Free State

Corrmun i ty numbe r 1.1 1.2 1. 1. 1 1. 1. 2 A B 111101111 1111100 000011000 100100010 Re I eve numbe r 847882243 6500395 217715468 004482617 176351641 5309731 099379894 665138130

Species Group A

Rhus pyroides IRRRRR+ R+I I I I Acacia karroo IR+RRR+R 11 R 1+ R + I I Prot asparagus laricinus 1+++R11 11 I RR I+RR I I Cyperus marginacus IBBBB+ A 1+ I 3 1 + I Al I Verbena bonariensis I R++ RRI RRI R I R I Cymbopogon excavatus IR++ R I R I I I Vigna vexillata IRR RR I I I I Asclepias rrucicosa IR R RR IR IR I I Crotalaria virgulaca I R+ R I I I I Bromus catharticus I RR+ I I I I Hyparrhenia hirta IAA+ IA I + I I Ranunculus multifidus I + R +1 + I R IR I Gomphostigma virga tum IR+ + I + I + I I EquiseCum ramosissimum 11 I I + I I Rumex lanceolatus I + R I I R I I Juncus exsertus 1+ A I I I 1

Spec ies Group B

Pulicaria scabra R I+R R R I Fuirena coerulescens I 1 1 + R I Phragmites australis R 1+1 +1

Species Group C

Aster squamatus 1++ +R RRRIRR RRR I + I I Lobelia thermalis IRR R ++11+++RR I I I Trirol ium pratense I RR R +I+R+RR RI IR RRI Agrostis lachnantha IR +1 R RIA++ +1 ++ + I 1 1 I Berti I a erec t a IR + R 11A I + I I

Spec ies Group 0

Oenothera rosea I R++ +IR IRRRRR R I Conyza bonariensis 1+ I R IRRRR R I + Echinoehloa haploclada I B 3 R I 13A R R IR+ Secaria pal I ide-rusea I + I R I Bl R RI R Verbena orricinalis I + I 1++ RR I

Spec ies Group E + lBI Hemarthria alcissima IA+ A+AAA3IB3ABAAAIABB1A+B3BI Cymbopogon plurinodis I RAR +A I ++RR R I R AR+R I R I Gal ium capense IR + 1+ IRR RRI++ + RRI RI Rumex crispus IR R RRR I + RI R R I I Typha eapensis I RR R I +B I A R A I I

Spec i es Group F A + I 1 AR Al IB3+BB +AAI Leersia hexandra +++1 Sehoenoplectus paludieola I R + 111A I IR1+ BB I Diplaehne fusca RR Carex schlechteri I + R IR I I 11 B I E l eoeharis paluscris ++ Cyperus difformis I I I

Spec ies Group G polygonum lapathirolium I + + 1+R I A +1 RIR R R IR R I Lobelia flaccida + + Falkia oblonga + I R+ I RI

Spec ies Group H Andropogon appendieulatus IA +R+B33AIRA+ 33AI 3A RABBIA 3+ BB4+1 Cyperus fastigiatus IA++ 3BA111+1BA1A I B31A+1BI+1 A 1 B31 Eragrostis plana I+B+ A AB+I+ BBA++I ++A+3 +IB A++ABA+I Paspalum dilatatum IAABAA ++BIAA+B 111 ++ RAARI +++R+ 1 Cynodon dactylon IB+B ARIR R+++RIA ++B+ + I R ++RI Pennisetum sphaeelacum IR R B A++IB A+BBBI B B +IA 3 A3AAI Berkheya radula I + R+ IRR1++RRI +R +1 R1R++R+1 Haplocarpha scaposa IRR + +R IR +R+R 1 + R+ RI ++ ++R 1 Cyperus longus IR A+ I +++A31+++ 1+A11 R+ +1 +1 Helictotrichon turgidulum 1 + RR RIR+RR1 +1 ++ RIR R++I Mariseus congestus I R ++++ 1 I + 11 R I +++ I + R 1 I Setaria nigrirostris I A R IR+ R RRI AAA+ 1 RAR + +1 Themeda triandra I R A R I +RR 1+ A R+I +R R+ RI Eragrostis curvula IRAAA +1 ++ 1+ + RA+I R3RRRI Eragroscis mierancha I + +R RR 1++ 1 +R 1A + RR I polygonum sal icirol ium I R R 1 R I R 1 1 + A + I +AA +R I Crinum bulbispermum I R RRRR 1 R 1 R R R1 RR R I Fingerhuthia sesleriirormis 1 R A 1RRB B I A A I RA I Cirsium vulgare I R R 1 R I R RI RI 234 S.-Afr.Tydsla.Plantk., 1992, 58(4)

(species group H - Table 1). Shrubs and trees are encounter­ 1.1.1(b) Pulicaria sea bra Variant (type releve: 165) ed in the deeper incised watercourses. The most conspicuous This variant is encountered in watercourses where the depth tree species that may be found occasionally are Acacia of streambed incision is intermediate (Figure 3B). Further­ karroo and Rhus pyroides (species group A - Table 1). In more, watercourses associated with this plant community disturbed places, Acacia karroo often invades and may even were in relatively good condition. Stream banks were found become dominant, presenting a serious bush-encroachment to be moist with large woody species mostly absent (Table problem (Bredenkamp et al. 1989). All trees in the area are 1). Diagnostic species are restricted to the forbs Pulicaria small and shrublike, seldom more than four metres in scabra and Fuirena coerulescens (species group B - Table height. 1). The large, hydrophilic reed Phragmites australis is also The Andropogon appendiculatus - Cyperus fastigiatus found in this plant community but is not necessarily diag­ Wetland, associated with permanently or seasonally wet nostic (species group B - Table 1). watercourses and adjacent streambanks, was divided into two major plant communities (Table 1): 1.1.2 Conyw. bonariensis - Setaria pallide-fusea Wet­ 1.1 Cymbopogon plurinodis - Hemarthria altissima Wet­ land (type releve: 20) land associated with intermediate or deep streambed This plant community is encountered in disturbed water­ incision; and courses with intermediate streambed incision (Figure 3B). 1.2 Leersia hexandra - Schoenoplectus paludicola Wetland Diagnostic species are the herbs Conyza bonariensis and associated with shallow streambed incision. Verbena officinalis as well as the pioneer grass species Setaria pallide-fusca (species group D - Table 1). These species are all indicators of disturbance. Other species with 1.1 Cymbopogon plurinodis - Hemarthria altissima a characteristically high constancy in this plant community Wetland (type releve: 153) are the forb Oenothera rosea as well as the graminoid This plant community is restricted to relatively fast to fast­ Echinochloa haploclada (species group D - Table 1). Note­ draining watercourses and is associated with intermediate or worthy is the low constancy of species listed under species deep streambed incision (Figures 3A & 3B). The most con­ group C within this plant community (Table 1). spicuous diagnostic species is Hemarthria altissima, a robust., perennial, stoloniferous grass species which can 1.2 Leersia hexandra - Sehoenopleetus paludicola Wet­ withstand periodic flash-floods and seasonal dry spells land (type releve: 6) (species group E - Table 1). The diagnostic forb species are This major plant community typically occurs in slow­ and the hydrophyte Galium capense, Rumex crispus Typha draining watercourses with a shallow streambed incision capensis (species group E - Table 1). The following sub­ communities were distinguished within this major plant community: A 1.1.1(0)

______~A ______~ 1.1.1 Aster squamatus - Lobelia thermalis Wetland (type releve: 181) This plant community is found in relatively undisturbed watercourses where streambed incision is moderately deep to deep (Figures 3A & 3B). Diagnostic forb and grass 'I( species are Aster squamatus, Lobelia thermalis, Trifolium WATERCOURSE pratense, Agrostis lachnantha and Berula erecta (species group C - Table 1). Two variants were distinguished within B

this plant community: 1.1.1(b)/1.1.2

\ , 1.1.1(a) Cyperus marginatus - Rhus pyroides Variant , (type releve: 181) ,I ,. This distinctive plant community is found in ravines with deep streambed incision (Figure 3A). This plant community is commonly associated with predominantly duplex and/or WATERCOURSE shallow soils in the catchment area, gully erosion, fast run­ off, flash-floods and bush encroachment. The streambanks c are generally dry and are characterized by a conspicuous 1.2 woody component. Diagnostic woody species, which occur as large shrubs or small trees, are Rhus peroides and Acacia karroo (species group A - Table 1). The small to medium­ , sized shrub Protosparagus laricinus commonly occurs in , ~4I , , association with the larger Acacia karroo. Other diagnostic I · " 1 WATERCOURSE , species include the forbs Verbena bonariensis, Vigna vexil­ lata and Asclepias fruticosa as well as the large, tufted, Figure 3 A schematic illustration of the variations in perennial graminoid Cymbopogon excavatus (species group watercourse topography and associated distribution of plant A - Table 1). communities. S.AfrJ.Bot., 1992,58(4) 235

(Figure 3C). In the study area these watercourses tend to be ACOCKS, l.P.H. 1988. Veld types of South Africa, 3rd edn. vlei-Iike in places. This plant community is associated with Mem. bOI. Surv. S. Afr. 57: 1 - 146. seasonally waterlogged, marshy stream banks. Large woody BREDENKAMP, G.l., JOUBERT, A.F. & BEZUIDENHOUT, H. species do not occur in this plant community (Table 1). The 1989. A reconnaissance survey of the vegetation of the plains most conspicuous diagnostic species is Leersia hexandra, a in the Potchefstroom - Fochville - area. S. Afr. 1. BOI. hydrophylic grass species commonly encountered in 55: 199 - 206. shallow, standing or slow-draining water. Other diagnostic FULS, E.R., BREDENKAMP, G.l., VAN RooYEN, N. & species include the hydrophilic forbs Schoenoplectus THERON, G.K. 1992a. The physical environment and major paludicola and Carex schlechteri as well as the large, tufted, plant communities of the Vredefort - Kroonstad - Lindley - Heilbron area, northern Orange Free State. S. Afr. 1. BOI. (in perennial graminoid Diplachne fusca, which is commonly press). associated with seasonally waterlogged soils (species group FULS, E.R., BREDENKAMP, G.I. & VAN RooYEN N. 1992b. F - Table 1). The plant communities of the rocky outcrops of the northern Orange Free State, South Africa. Vegelalio (in press). Concluding remarks FULS, E.R., BREDENKAMP, G.l. & VAN ROO YEN N. 1992c. All plant communities could be related to specific environ­ The plant communities of the undulating grassland of the mental conditions and are therefore ecologically distinguish­ Vredefort - Kroonstad - Lindley - Heilbron area, northern able and interpretable. Plant community variations in water­ Orange Free State. S. Afr. 1. BOI. 58: 224 - 230. courses of the study area are mainly ascribed to differences GillBS RUSSELL, G.E., REID, e., VAN Rooy, l. & SMOOK, in streamflow tempo, streambed incision, streambank wet­ L. 1985. List of species of southern African plants, 2nd edn, ness and period of wetness. Soil characteristics apparently Part 1. Mem. bOI. Surv. S. Afr. 51 : 1 - 152. do not play a major role, except in catchment areas where GillBS RUSSELL, G.E., WELMAN, W.G., RETIEF, E., duplex soils are predominant. More than one of the plant IMMELMAN, K.L., GERMISHUIZEN, G., PIENAAR, B.1., communities may be encountered along the passageway of a VAN WYK, M., NICHOLAS, A., DE WET, e., MOGFORD, particular river/stream, depending on variations in topogra­ I.e. & MULVENNA, I. 1987. List of species of southern phy, streambed incision and drainage tempo. African plants, 2nd edn, Part 2. Mem. bOI. Surv. S. Afr. 56: 1 - Management of catchment areas and the watercourses that 270. drain them should take variations in vegetation and water­ HILL, M.O. 1979. TWINSPAN - a FORTRAN program for arranging course ecology into account. This delineation of the plant multivariate data in an ordered two-way table by classification communities and associated habitats of the watercourses of of the individuals and attributes. Cornell University, Ithaca, the northern Orange Free State should be used as the basis New York. for future management and conservation of these areas. KOOU, M.S ., BREDENKAMP, G.1 . & THERON, G.K. 1990. Future research will concentrate more specifically on the Classification of the vegetation of the B land type in the north­ western Orange Free State. S. Afr. 1. BOI. 56: 309 - 318. conservation status and ecological importance of the species LAND TYPE SURVEY STAFF. 1984. Land types of the maps and plant communities of this region. 2626 Wesrand, 2726 Kroonstad. Mem. Agric. Nal. Resources S. Afr. 4: 1 - 441. Acknowledgements MENTIS, M.T. & HUNTLEY, B.1. 1982. A description of the The assistance of Mrs M.S. Deutschlander is much appre­ Grassland Biome Project. S. Afr. Nal. Sci. Prog. Rep. 62: 1 - ciated. The research was funded by the Department of 29. Environmental Affairs. MUELLER-DOMBOIS, D. & ELLENBERG, H. 1974. Aims and Methods of Vegetation Ecology. Wiley, New York. References SCHEEPERS, lC. 1975. The plant ecology of the Kroonstad and ACOCKS, I.P.H. 1953. Veld types of South Africa, 1st edn. Mem. Bethlehem areas of the Highveld Agricultural Region. D.Sc. bOI. Surv. S. Afr. 28: 1 - 192. thesis, University of Pretoria.