van staden woud.qxd 2006/04/17 08:38 PM Page 15 A floristic analysis of forest and thicket vegetation of the Marakele National Park P.J. VA N STADEN & G.J. BREDENKAMP Van Staden, P.J. and G.J. Bredenkamp. 2006. A floristic analysis of forest and thicket vegetation of the Marakele National Park. Koedoe 49(1): 15–32. Pretoria. ISSN 0075- 6458. One of the major plant communities identified in the Marakele National Park was for- est. It became clear that this major forest community contained various forest and thick- et communities. Relevés compiled in the forest were classified by TWINSPAN and Braun-Blanquet procedures identified six communities that are hierarchically classified. The forests dominated by Podocarpus latifolius and Widdringtonia nodiflora represent Afromontane Forests, whereas the Buxus macowanii-dominated dry forests and Olea europaea subsp. africana represent Northern Highveld Forests. A further group of com- munities represent thickets on termitaria with floristic affinities to both savanna and for- est. The floristic composition and relationships of the forest and thicket communities are discussed. Key words: Afromontane forest, Afrotemperate forest, classification, National Park, ter- mitaria, thicket, TWINSPAN. PJ van Staden, Centre for Wildlife Management, University of Pretoria, Pretoria, 0001 Republic of South Afirca; GJ Bredenkamp , Department of Botany, University of Pre- toria, Pretoria, 0001 Republic of South Afirca ([email protected]). Introduction Van Staden (2002) indicated that various plant communities occurred within these In an overview of the vegetation of Marakele forests, though they are not yet described. National Park, Van Staden & Bredenkamp This paper aims to describe the forest plant (2005) recognised five major plant commu- communities of the Marakele National Park, nities, of which one represents forests. These to provide an inventory of the biodiversity of forests are mostly restricted to moist, shel- the plant community at the plant species tered valleys, and represent typical Marakele level. Afromontane Forest (Von Maltitz 2003). Although Du Preez et al. (1991) classified this type of forest as typical Afromontane Study area Forests, the Marakele forests exist under much drier conditions than in the Drakens- The study area was described in detail by Van berg (Von Maltitz 2003). These forests occur Staden (2002) and Van Staden & Bre- in specific niches in deep valleys, protected denkamp (2005), and are therefore only gorges and ravines along the eastern and briefly mentioned here. The study area cov- western slopes of the Drakensberg mountain ers 290.51 km² in the southwestern part of range. the Limpopo Province between 27°30'E– 27°45'E and 24°15'S–24°30'S. Marakele Indeed, some of the Marakele forests are National Park is situated mainly in the Water- very dry and represent a very rare and berg Moist Mountain Bushveld (Low & restricted plant community classified by Von Rebelo 1996), in the Savanna Biome Maltitz (2003) under Northern Highveld (Rutherford & Westfall 1994). The vegeta- Forests. tion of the study area includes Acocks’ ISSN 0075-6458 15 Koedoe 49/1 (2006) van staden woud.qxd 2006/04/17 08:38 PM Page 16 (1988) Sour Bushveld (Veld Type 20), too small to delineate. Additional sample plots were Mixed Bushveld (Veld Type 18), Sourish subjectively placed within the termitaria vegetation. Mixed Bushveld (Veld Type 19) and North- For the purpose of this study, a standard sample plot Eastern Mountain Sourveld (Veld Type 8). size of 10 m x 20 m was fixed and used throughout The underlying parent rock of the biggest the study area. This plot size is considered adequate part of the study area consists of sandstone for surveys in savanna vegetation by Coetzee (1975), of the Kransberg Subgroup, Sandriviersberg Coetzee et al. (1976), Westfall (1981), Van Rooyen Formation. Sandstone of the Matlabas Sub- (1983) and Gertenbach (1987). group, Aasvoëlkop Formation, occurs in the At each sample plot a list is compiled of all the southwestern and southern parts; shale and species that occur. A cover-abundance value was mudstone of the Matlabas Subgroup given to each species according to the cover-abun- Aasvoëlkop Formation, Groothoek Mud- dance scale, used by Braun-Blanquet and given by stone Member; a conglomerate outcrop of Mueller-Dombois & Ellenberg (1974) and Werger the Matlabas Subgroup, Aasvoëlkop Forma- (1974), and modified by Barkman et al. (1964): tion are found in the western part. These rock formations resulted in the complex mountain 5 - Any number of plants, with cover >75 % of the sample plot. topography of the Waterberg. Within this 4 - Any number of plants, with cover > 50–75 % of complex topography, the forests are restrict- the sample plot. ed to the relatively moist kloofs, mostly with 3 - Any number of plants, with cover > 25–50 % of small rivers. the sample plot. 2a -Covering between 5–12 % of the sample plot The soils that have developed on the parent area independent of abundance (indicated as A in materials range from shallow sandy to deep the tables). sandy soils on sandstone and clayey soils on 2b -Covering between 13–25 % of the sample plot area independent of abundance (indicated as B diabase and mudstone. in the tables). The rainfall varies from 556 mm to 630 mm 1 - Numerous, with cover of 5 % or less. + - Individuals with cover of < 1 %. per annum and occurs mainly during the r - Usually a single individual with a cover of summer months. This is considerably lower <1%. than the rainfall limits described for forests in summer rainfall area by Rutherford & Although Van Staden (2002) recorded various habi- Westfall (1994). The study area experiences tat variables, only the following habitat classes are used in this study (see Table 1): warm, wet summers with temperatures of up to 32 ºC and cool dry winters with frost in The altitude of each sample plot was recorded using the low-lying areas. an altimeter and is given in meters. The slope of the terrain of each sample plot was measured in degrees, using an optical clinometer. Methods The following classification of slope units (Westfall 1981), were used in this study: Analysis Symbol Description Class In the overview of the vegetation of the Marakele L level 0.00° - 3.49° National Park, Van Staden (2002) used 130 sample G gentle 3.50° - 17.62° plots, located in a stratified random manner in M moderate 17.63°- 36.39° physiographically and physiognomically homoge- S steep 36.40° neous units, delineated on 1:50 000 scale aerial pho- The aspect of the terrain where each sample plot is tographs (Bredenkamp & Theron 1978; Westfall situated was determined using a compass. Aspect is 1981; Gertenbach 1987). The number of sample given in the eight compass directions, namely: plots for each delineated physiographic-physiog- nomic unit was determined according to the size of N - North S - South each delineated unit. Termitaria were not included in NE - Northeast SW - Southwest the placing of the sample plots. Although they could E - East W - West be recognised on the aerial photographs, they were SE - Southeast NW - Northwest Koedoe 49/1 (2006) 16 ISSN 0075-6458 van staden woud.qxd 2006/04/17 08:38 PM Page 17 The surface rock cover in each sample plot was esti- on the Marakele National Park as the Olea mated as a percentage of stones (> 20 mm diameter), europaea subsp. africana-Diospyros whyteana boulders and rocky outcrops. The following five Major Community. Obvious variation in plant classes were used, based on its potential influence on species composition and dominance was mechanical use (ploughing) (Van der Meulen 1979; observed within this major community. The Westfall 1981): floristic composition of the Olea europaea Symbol Class Description subsp. africana-Diospyros whyteana Major O < 1 % No limitation on mechanical Community is given in Table 1. utilisation Van Staden & Bredenkamp (2005) described L 1 - 4 % Low limitation on mechanical this major community as having a large utilisation M 5 - 34 % Moderate limitation on number of diagnostic species, all being trees mechanical utilisation or shrubs, which distinguish this forest vege- H 35 - 84 % High limitation on mechanical tation from any other plant community utilisation occurring in the park. These diagnostic V 85 - 100 % No mechanical utilisation species included Pappea capensis, Mimu- possible sops zeyheri, Olea europaea subsp. africana, Land type was read from the Land Type maps. Cussonia paniculata, Diospyros whyteana, Euphorbia ingens, Rhus leptodictya, Cryp- tolepis transvaalensis, Podocarpus lati- Synthesis folius, Maytenus undata, Zanthoxylum The full dataset was captured on the mainframe com- capense, Myrsine africana, Canthium gilfil- puter of the University of Pretoria, in the BBNEW lanii, Ficus sur, Calpurnia aurea, Olea software package. It was then exported to be used in capensis and Grewia occidentalis. the software package BBPC (Bezuidenhout et al. Although different plant communities can be 1996). After a TWINSPAN classification (Hill 1979), the output of the resulting classification was import- recognised within these forests and bush ed into a spreadsheet, for refinement by Braun-Blan- clumps, certain species, e.g., Olea europaea quet procedures (Behr & Bredenkamp 1988). The subsp. africana, Ficus sur, Cryptolepis final classification of the relevés was then interpret- transvaalensis, Cussonia paniculata and ed for identification of major communities for the Euphorbia ingens were prominent through- entire park. The relevés representing the forests and out the range of this major community. thickets were then extracted, subjected to TWINSPAN (Hill 1979) and exported to be used in the software The forest communities occur in the kloofs, package BBPC (Bezuidenhout et al. 1996) for or as thickets in bush clumps on south and refinement by Braun-Blanquet procedures. The east-facing slopes and also as dense thickets results are summarised in a phytosociological table on termitaria on the plains. The kloofs are (Table 1). the most sheltered of the geomorphology classes found in the study area, with water in the watercourses draining down the kloofs.