A CLASSIFICATION AND DESCRIPTION OF THE SHRUBLAND VEGETATION ON PLATBERG , EASTERN FREE STATE , SOUTH AFRICA

The natural environment is constantly under threat from human-related activities. Platberg, overlooking the town of Harrismith in the Free State, is an inselberg that presents a refuge for indigenous plants and animals. The natural vegetation of the area is threatened by various farming and grazing practices, as well as by commercial development. In order to obtain baseline data and to obtain an improved understanding of the long-term ecological processes, the vegetation of Platberg was investigated to establish Afroalpine fl oristic links to the Drakensberg, as well as for the management of natural resources. From a Two-Way Indicator-Species Analysis (TWINSPAN) classifi cation, refi ned by Braun–Blanquet methods, four major plant communities were identifi ed, which were subdivided into fynbos, wetland, woody/shrub and grassland. A classifi cation and description of the shrubland is presented in this article. The analysis showed the shrubland divided into 20 different plant communities, which are grouped into eight major communities, 13 sub-communities and eight variants. A total of 450 species was recorded from 109 relevés. A total of 24 endemic, or near-endemic, and Red Data species belonging to the Drakensberg Alpine Centre (DAC) was collected, with 22 alien (introduced) species also being recorded. Numerous fl oristic links with the DAC, the Cape Floristic Region and the Grassland Bioregions to the north and west were found. Conservation implications: The fl oristic composition and community analysis proves Platberg to be an important centre for plant diversity, with high species richness, a variety of habitats, and complex ecosystems. This description of the woodland communities can be used to assist with the setting of criteria for the management and protection of inselbergs in the province.


INTRODUCTION
The natural environment is continually under threat from development, pollution, alien species invasions, and other human-related actions (Millennium Ecosystem Assessment 2005). The increasing pressures imposed by such actions threaten to lead to a loss of plant and animal species, which could lead to the degradation of an area. The prevention of large-scale loss of biodiversity is a daunting challenge facing the world today (Huntley 1991). In order to conserve our natural resources, ecosystems must be studied to allow for the compilation of an inventory of our natural resources. Platberg, in the Eastern Free State, overlooking the town of Harrismith, is an inselberg that serves as a refuge for indigenous plants and animals.
Platberg is located at latitude S 29°-10' and longitude E 28°-16' on the N3 highway between Johannesburg and Durban (see Figure 1). The altitude ranges from 1 900 m to 2 394 m, with the surface area of the study site being approximately 3 000 ha. The slopes are steep, with numerous vegetated gullies and boulder scree slopes below the vertical cliffs, which are 20 m to 45 m high. Waterfalls cascade down the southern cliffs after rain.

Vegetation
Platberg falls within the Grassland Biome (or the Drakensberg Grassland Bioregion; Mucina & Rutherford 2006), with generally short to tall sour grasses (Acocks 1988;Low & Rebelo 1998). It also has elements of Fynbos and False Karoo (Acocks) or Succulent Karoo (Low & Rebelo 1998), as well as elements of Temperate and Transitional Forests, and specifically of the Highland Sourveld (Acocks) biomes.
The vegetation description presented by Mucina & Rutherford (2006) shows the study area located within the Northern Drakensberg Highland Grassland (Gm5) and Lesotho Highland Basalt Grassland (Gd8), both within the Drakensberg Grassland Bioregion.

Geology
Platberg consists of layers of the Karoo Supergroup which stratigraphically lie immediately below the volcanics of the Drakensberg Formation, which is the youngest (Jurassic, 65 million years) unit of the Stormberg Group (Brand, Du Preez & Brown 2008). Figure 2 shows a terrain-form sketch of the study area. The steep slopes are composed of shale and mostly sandstone of the Clarens Formation intersected by dolerite dykes, resulting in benches, deep ravines and terraces. Numerous sandstone and basalt boulders form scree and boulder slopes, resulting Snow, which is recorded at the top of Platberg during most winters, can remain on the ground for up to two weeks (D. Weaver, G. Weaver, S. Falanga & C. Gobbles pers. comm. 2008). Water in south-facing gullies may stay frozen for several weeks at a time (Mucina & Rutherford 2006;Van Zinderen Bakker 1973). Possible heave soils are present on Mtabazwe (the highest point on Platberg; personal observation c.p.w. Hilliard & Burtt 1987) and might be a significant factor in controlling vegetation at high altitudes (HilIiard & Burtt 1987;Mucina & Rutherford 2006).

METHODS
A total of 109 sample plots was placed within the shrubland communities of Platberg. The aim of the study was to sample above the 1 900 m contour, in order to work within the limits set by Killick (1963Killick ( , 1978aKillick ( , 1978b, who regarded the region in the Drakensberg above the 1 800 m as a distinct floristic region, namely the Afroalpine Region. Plot sizes were fixed at 100 m² (Du Preez 1991, 1992Du Preez & Bredenkamp 1991a;Malan 1998;Westhoff & Van der Maarel 1980;Whitaker 1980,). In all sample plots, each species was recorded, with all woody plants being counted and the cover abundance being estimated using the Braun-Blanquet cover scale (Mueller-Dombois & Ellenberg 1974;Whitaker 1980). Over 1 500 floristic collections were made and identified at the UFS Herbarium and the National Herbarium, Pretoria. All taxa names conform to Germishuizen & Meyer (2003). In the structural assessment of the woody vegetation, all woody species were divided into three groups based on height, namely shrubs (> 0-2 m), trees (> 2-6 m) and tall trees (> 6 m) (Brand 2007).
Habitat, as well as floristic data, was processed using TURBOVEG (Hennekens 1996a). A first approximation was undertaken using the two-way indicator-species analysis classification (TWINSPAN) algorithm (Hill 1979). The result was refined with the aid of the MEGATAB table editing program (Hennekens 1996b), in order to obtain a phytosociological table indicating the classification of the vegetation types, with their species composition. Further refinement of the classification was undertaken through the application of Braun-Blanquet procedures (Barbour, Burk & Pitts 1987;Kent & Coker 1992).

Vegetation classification
A total of 450 species was recorded for the woody shrub vegetation. The floristic analysis identified 20 plant communities, which are grouped into eight major communities (see Table 1

Themeda triandra-Watsonia lepida community
The Themeda triandra-Watsonia lepida community is found on all aspects of the summit plateau and the steep footslopes. The altitude varies between 1 920 and 2 340 m, with the soil being shallow (40 mm) to deep (300 mm). The summit soils are well drained and composed of degraded igneous rocks. The footslopes are composed of a mix of igneous and sandstone of the Clarens Formation of Ib soil type. Rock cover varies from 5% to 45%, with erosion and levels of trampling varying from zero to moderate or high. For small trees, the total canopy cover varies between 5% and 30%, while tall trees had a cover ranging between 5% and 10%. The total canopy cover varied from 5% to 80% for shrubs. Herbaceous cover varied between 5% and 50%.

Themeda triandra-Watsonia lepida-Harpochloa falx sub-community
The small geophyte sub-community is located on all aspects of Platberg, including on the flat, rocky summit outcrops and on the very steep slopes > 45°. Soils are derived from either igneous summit rocks or sedimentary Cave Sandstone. Soils are shallow, being between 10 and 60 mm, or > 300 mm deep, and seasonally damp. Moderate surface erosion was recorded, with no evidence of trampling. Rock cover was found to vary between 20% and 50%.
The sub-community is characterised by the presence of the small geophyte Albuca humilis and the forb Wahlenbergia cuspidata (Species Group C). Prominent species include the grass Harpochloa falx (Species Group I), and Eragrostis curvula (Species Group Y); the sedge Ficinia gracillis (Species Group I); and the geophyte Watsonia lepida (Species Group M). The average number of species recorded per 100 m² was 40.5.
Two variants of the sub-community are recognised:

Themeda triandra-Watsonia lepida-Andropogon appendiculatus sub-community
The Themeda triandra-Watsonia lepida-Andropogon appendiculatus sub-community is located on the cool southern aspects, on terrain with gradients ranging from 8° to > 45°. It has two altitudinal locations, a lower one at 1 976 to 2 150 m on the sandstones of the Clarens Formation, and a higher one at 2 287 m, on the rolling summit plateau. Rock cover varies between 5% and 35%. Soils are 300 mm deep and seasonally moist, with no signs of erosion or trampling. The canopy cover, which varies between 5% and 40%, is provided by shrubs.
The sub-community, which is characterised by species from Species Group E (Table 1)

Themeda triandra-Watsonia lepida-Printzia pyrifolia sub-community
The small sub-community is located on the southern and southwestern aspects, between 1 940 m and 2 057 m on the very steep slopes below the basalt cliffs on rocky ridges and outcrops of sandstone and dolerite. Rock size is > 500mm, with rock cover ranging between 10% and 40%. No trampling or erosion was noted. Soils are shallow (60 to 1200 mm) and > 300 mm deep. Canopy cover for shrubs varies between 15% and 60%.
Species from Species Group J, namely the shrubs Printzia pyrifolia and Indigofera hewittii and the perennial bunch grass Helictotrichon turgidulum are diagnostic for this variant.
The small tree Leucosidea sericea and the shrubs Myrsine africana (Species Group AL) Printzia pyrifolia (Species Group J), and Calpurnia sericea (Species Group T) dominate the vegetation. A well-developed grass layer includes Aristida monticola (Species Group K), Themeda triandra (Species Group M), Cymbopogon dieterlenii (Species Group T), and Ehrharta erecta (Species Group AL). In this small community, an average of 37.3 species per 100 m² was recorded.

Themeda triandra-Watsonia lepida-Tristachya leucothrix sub-community
The sub-community is located at altitudes ranging between 2 027 m and 2 047 m, on various aspects, with gradual to steep slopes on the mid-slopes below the basalt cliffs. Rock size is > 200 mm. Rock exposure ranges from 0% to 35%. Levels of trampling and erosion are zero to moderate. Soils are well drained and 40 mm to 200 mm deep. The sub-community has shrubs, which provide canopy cover between 5% and 50%.
The sub-community is characterised by species from Species Group L, including the forb Gerbera piloselloides, the tuberous Pentanisia prunelloides and the geophyte Cyanotis speciosa. The vegetation is dominated by the grasses Themeda triandra and Tristachya leucothrix (Species Group M). The shrub Leucosidea sericea and forb Senecio inornatus (Species Group AL) are prominent. The grasses Eragrostis racemosa (Species Group M) and E. curvula (Species Group Y) are prominent in dense patches scattered throughout the area.
The sub-community occurs on rocky, grassed terrain on the Farm Platberg. Evidence of the impact of grazing by cattle and other smaller livestock, as well as their paths, is widespread. An average of 28 species per 100 m² was recorded for the degraded community.

Leucosidea sericea-Hyparrhenia hirta community
The Leucosidea sericea-Hyparrhenia hirta community is located on the warm northern and north-western aspect, at 1 930 to 2 052 m above sea level, on steep to very steep slopes (16° to 45°). Rock size varies from < 1 mm, 10 to 50 mm, with boulders > 200 m. The community is located on Cave Sandstone with < 5% rock exposure on seasonally damp soils with depths ranging from 60 to 100 mm and > 300 mm. Though no surface erosion was recorded, levels of trampling varied from none to heavy. The total percentage canopy cover for small trees was 5% to 10%, and 5% for shrubs, while herbaceous cover ranged from 7% to 50%.
The perennial grass Hyparrhenia hirta (Species Group N) was found to be characteristic for the community. The vegetation is dominated by the small tree Leucosidea sericea (Species Group AL) and the grass Hyparrhenia hirta (Species Group N). The shrubs Calpurnia sericea (Species Group T) and Rhus discolor (Species Group P); the grass Eragrostis curvula (Species Group Y); and the forbs Senecio inornatus (Species Group AL) and Clutia affinis (Species Group AF) are prominent locally. An average of 28.7 species per 100 m² was recorded in the six relevés.

Rhus pyroides-Pteridium aquilinum community
The shrub community occurs at low altitudes of between 1 996 and 2 034m on the footslopes of the Platberg, on the southern and south-western aspects. The slope was found to vary from gradual to very steep. Soils are a mix of Cave Sandstone and igneous rocks. Rock cover ranges from 0% to 25%, with no erosion or trampling seen. Soils are seasonally damp and 180 to > 300 mm deep. Canopy cover ranges between 70% and 95%, and is dominated by the 1.8 m tall fern, Pteridium aquilinum.
The fern, Pteridium aquilinum (Species Group O), is diagnostic and dominant for this community. Prominent species include Calpurnia sericea (Species Group T) and Buddleja salviifolia (Species Group X); the perennial grass Eragrostis curvula; the shrub Rhus pyroides (Species Group Y); and the forb Senecio inornatus (Species Group AL).
Stands of the dense and distinct community, which show the invasion of the bracken into the grassland are indicative of disturbance (Du Preez 1991). Four relevés, with an average of 25.1 species per 100 m² relevé, were recorded for the community.

Diospyros whyteana-Euclea crispa community
The community is located at altitudes between 1 944 m and 2 088 m, on the north and north-eastern aspects, on moderately angled footslopes. Rock cover is 0% to 10% with stones > 200 mm. Soils are generally > 300 mm deep, with some medium depth (100 to 120 mm) sections. The geology is Cave Sandstone with scree rubble (a mixture of dolerite and basalt). Moderate to high levels of trampling and soil erosion were recorded. The canopy cover was found to be 20% to 70% for small trees and 10% to 40% for shrubs. The herbaceous cover is poor, and was found to vary between 0% and 5%.

Diospyros whyteana-Euclea crispa-Themeda triandra sub-community
The sub-community is located at relatively low altitudes of between 1 940 m and 2 084 m on the eastern, south-eastern and northern aspects. The slopes are moderate to steep. The bedrock geology is sandstone and shale of the Clarens Formation. The community is located on the foot or mid-slopes, with moderate to high levels of erosion and trampling. Rock exposure ranges between 0% and 10%, with an exception of 25% for one relevé.
The soils are damp, with black humus > 300 mm deep. Woody species dominate the sub-community with the canopy cover for small trees ranging between 20% and 70%, while shrubs have between 10% to 80% cover.
The sub-community is characterised by the absence of Species Groups Q and R and is dominated by the small trees and shrubs Diospyros whyteana, Maytenus heterophylla, Rhus dentata (Species Group S) and Leucosidea sericea (Species Group AL). Other prominent species include Buddleja salviifolia (Species Group X),

Kiggelaria africana-Crassula lanceolata community
The Kiggelaria africana-Crassula lanceolata community is composed of tall to small trees and comprises a significant proportion (27%) of the shrub/woody vegetation. It has two sub-communities, which are located on rocky ridges and scree slopes, predominantly on the south and south-west aspects, with scattered components on the south-eastern and northern slopes. The gradients are steep to very steep. The bedrock geology is sandstone and shale from the Clarens Formation, with the presence of igneous scree boulders > 500 mm. Rock exposure ranges from 0% to 40%. Altitudes range between 2 006 m and 2 238 m. The soils are seasonally damp, shallow (10 to 100 mm), or over 300 mm deep. Little or no trampling or erosion was found to be present. The canopy cover for small trees is between 5% and 15%, and for tall trees is 25% to 80%. There is a welldeveloped under-story layer of forbs and succulents, with cover varying between 15% and 75%.
The community is characterised by species from Species Group V and comprises the tall tree Kiggelaria africana, the climber Zehneria scabra, and the succulent Crassula lanceolata sp. transvaalensis.
The vegetation has a well-developed tree and shrub layer, and is dominated by the tall tree Kiggelaria africana (Species Group V); the small tree Buddleja salviifolia (Species Group X); the shrub Rhus pyroides (Species Group Y); the tall, under-story forb Stachys grandifolia (Species Group AE); and the ubiquitous shrub Leucosidea sericea (Species Group AL). Other woody species with significant presence are Heteromorpha arborescens, Dioscorea sylvatica (Species Group Y), and the small shrub Myrsine africana (Species Group AL). The tall forb Senecio inornatus (Species Group AL) is locally prominent. The grass layer is poorly developed, represented by only two grasses: Eragrostis curvula (Species Group Y) and Ehrharta erecta (Species Group AL). A total species count of 596 in 22 relevés averages 27.1 species per 100 m².

Kiggelaria africana-Crassula lanceolata-Senecio isatideus sub-community
The Kiggelaria africana-Crassula lanceolata-Senecio isatideus subcommunity is located on the south and southwestern midslopes, with altitude ranging between 2 006 m and 2 219 m. The slopes are steep to very steep. The bedrock geology is sandstone of the Clarens Formation and basalt at the contact of the summit volcanics. Rock exposure varies between 5% and 35%. Surface erosion and trampling vary from zero to moderate. Soils are seasonally damp, shallow (20 to 200 mm), or over 300 mm deep. The canopy cover for tall trees is 10%, and for small trees is between 5% and 15%. For shrubs, cover is between 20% and 75%.
The sub-community is characterised by the absence of species from Species Groups U, Z and AC. The vegetation is dominated by the small tree Leucosidea sericea (Species Group AL), and the shrubs Buddleja salviifolia (Species Group X) and Stachys grandifolia (Species Group AE). The tree Kiggelaria africana (Species Group V) and the two grasses Eragrostis curvula (Species Group Y) and Ehrharta erecta (Species Group AL) have significant presence.
Other species of importance include the tree Heteromorpha arborescens, the climber Dioscorea sylvatica (Species Group Y), and the tall forb Senecio inornatus (Species Group AL). An average of 31.29 different species per 100 m² was recorded for the subcommunity.

Kiggelaria africana-Crassula lanceolata-Zehneria scabra sub-community
The sub-community is located on the extensive, mobile scree

Buddleja loricata-Rhus divaricata community
The community is located on the southern side of the Platberg, at altitudes ranging between 2 094 m and 2 119 m, on the extensive boulder scree slopes located on the steep to very steep shoulder below the summit basalt. The geology is sandstone bedrock, with the scree boulders composed of summit volcanics. Estimation of rockiness is difficult, as the communities are located almost exclusively on the vegetation growing on the accumulated, unstable boulders. Levels of trampling and erosion within the constraints of these communities range from zero to moderate. Soil depths vary greatly, depending on the location of the accumulated humus trapped by the boulders, from very shallow (10 mm) to > 300 mm deep. Canopy cover for tall trees ranges from 5% to 10%, for small trees from 5% to 50% and for shrubs from 20% to 100%. Herbaceous cover ranges from 1% to 50%, with some relevés having up to 75% cover.
The community is defined by species from Species Group AD, including the shrubs Buddleja loricata and Rhus divaricata.
The community is dominated by the tree Leucosidea sericea (Species Group AL), the shrub Buddleja loricata (Species Group AD), the tall under-story labiate forb Stachys grandifolia (Species Group AE), and the common climber Clematis brachiata (Species Group AG). The shrub Rhus divaricata (Species Group AG) is locally abundant. The paucity of grasses, forbs and geophytes for the community is a feature of the substrate, which is characterised by large, mobile boulders, which have very shallow, poorly developed soils. An average of 18.2 species per 100 m² was recorded for the community.

Buddleja loricata-Rhus divaricata-Gallium scabrelloides sub-community
The sub-community is located at altitudes of between 2 095 m and 2 225 m on the cool, moist south slopes of the Platberg, below the vertical igneous rocks on the steep to very steep slopes. Very large packed boulders comprise the scree community. Soils are damp, very shallow (10 mm) or > 300 mm deep. Canopy cover varies from 10% to 20% for tall trees, 5% to 60% for small trees and 20% to 80% for shrubs.
The sub-community is characterised by two species from Species Group AA: the soft, lax forb Galium scabrelloides and the fern Polystichum pungens.
The dominant species include the tree Leucosidea sericea (Species Group AL), the shrub Buddleja loricata (Species Group AD), the forb Stachys grandiflora (Species Group AE), and the climber Clematis brachiata (Species Group AG). There is poor representation of grasses, geophytes and forbs. The sub-community is regarded as species poor, with an average of 18.1 species per 100 m², which is the second lowest average for the woody shrub vegetation. The loose packing and precarious nature of the boulders, with very shallow soils, partially explains the paucity.

Buddleja loricata-Rhus divaricata-Stachys grandifolia sub-community
The sub-community is located on the mid-slope, at approximately 2 200 m on the southern aspect, with steep to very steep slopes. The geology is sandstone of the Clarens Formation and scree boulders of the Stormberg Volcanics. Scree boulders give rock exposure of between 10% and 20%, with soil depths ranging from shallow (10 mm

Leucosidea sericia-Asparagus ramosissimus community
The community is located on a north-western and south-eastern aspect, at altitudes ranging between 2 015 m and 2 236 m. The community is located on the footslope leading to the locally named 'Monkey Point', and on the south-eastern section of the promontory. Group AG), and Parietaria debilis (Species Group AI); the small shrub Myrsine Africana; and the under-story grass Ehrharta erecta (Species Group AL). An average of 25.8 species per 100 m² was recorded for the community, which is significantly lower than has been recorded for similar communities by Bredenkamp and Brown (2003), Grobler et al. (2002) and Robbeson (1998).
The community has two sub-communities:

Asparagus ramosissimus-Leucosidea sericea-Fraxinus angustifolia sub-community
The sub-community is located on the footslope below the Cave Sandstone of the Clarens Formation, on the north-western and south-eastern aspects. Soils are deep, black and damp, with depths greater than 500 mm. Igneous boulders cover less than 5% of the area. The sub-community is a forest stand with a 25% cover provided by tall trees, 60% for small trees, and 10% for shrubs. Slopes vary from 0° to 8°, with moderate levels of erosion and trampling evident. The forest floor is transsected by numerous trails, indicating significant use by wildlife. The trees form a community with poorly developed stratification.
The forest patch is mostly open below the tall trees, with limited tree and shrub growth. Low, caespitose forbs cover the ground. Speciation is low, with > 50% bare soil.
The sub-community is characterised by species from Species Group AH, including the alien tree Fraxinus angustifolia; the forbs Solaum macrocarpon and Cerastium indicum; the grass Bromus leptocladus; and the sedge Schoenoxphium lehmannii.
The vegetation is dominated by the tall tree Fraxinus angustifolia (Species Group AH); the small tree Leucosidea sericea (Species Group AL); the shrubs Rhus divaricata (Species Group AD) and Myrsine africana (Species Group AL); and the forb Stachys grandifolia (Species Group AE). Prominent species include the tree Kiggelaria africana (Species Group V); the weedy forb Achyranthus aspera var. sicula (Species Group S); and the two grasses Bromus leptocladus (Species Group AH) and Ehrharta erecta (Species Group AL). The average number of species recorded per 100 m² was 16.7, which was the lowest count for all the communities.
Fraxinus angustifolia an alien emergent tree, which, along with Leucosidea sericea, forms the major component of the forest. Some of the Leucosidea sericea individuals are more than 6 m tall, with DBH of 500 mm forming an unusually tall and dense stand of Leucosidea trees. Lithophytes and ferns cover numerous large igneous boulders. The forest has a 90% to 100% canopy cover. Sunlight penetrates gaps in the canopy with numerous thickstemmed (20 to 50 mm) climbers, mostly Clematis brachiata, festooning the trees.

Asparagus ramosissimus-Leucosidea sericea Plectranthus grallatus sub-community
The sub-community is located on the cool and very cool southeastern aspects of the Platberg on private farms. The subcommunity extends from the footslopes, on gradual to very steep slopes on the mid-slope below the cliffs. Soils are deeper than 500 mm, and are damp, composed of black humus-rich soil, which shows moderate erosion and trampling. Altitudes vary from 2 030 m to 2 250 m. Rockiness is less than 5%. The geology is a mix of Cave Sandstone of the Clarens Formation and the igneous rock capping Platberg. The canopy cover for tall trees is 25%. For small trees cover it is 60%, and for shrubs it is 10%. The dense forest patch covers the very steep eastern slope of the Platberg. It forms a well-stratified forest community with a mix of emigrants (> 6 m), small trees and shrubs, with numerous ferns, forbs, soft grasses and lichens abundant on boulders and dead trees. Browsing and other animal utilisation is evident. Though three Podocarpus latifolius individuals have been recorded in the community (M. Cunningham, pers comm., 2005), none were found in the current study.
The species from Species Group AJ characterise the community, including the forb Cineraria dieterlenii; the large fern Polystichum wilsonii; and the geophyte Kniphofia caulescens.
The sub-community is dominated by the tall tree Rhamnus prinoides (Species Group AF); the small tree Leucosidea sericea (Species Group AL); the shrub Buddleja salviifolia (Species Group X); the under-story forb Plectranthus grallatus (Species Group AG); the soft prostrate herb Parietaria debillis; and the spiny forb Asparagus ramosissimus (Species Group AI). An average of 23 species per 100 m² was recorded for the community.

Senecio inornatus-Thamnocalamus tessellatus community
The community is located exclusively on the cool, southern side of the Platberg, between altitudes of 2 220 m and 2 316 m. It occurs in steep ravines and watercourses, along the base of the cliffs and growing along the only perennial stream in Donkey Pass. The lowest altitude at which Thamnocalamus tessellatus has been recorded is 1 980 m, in a south-facing gully. The community is in semi-shade, on gradual to steep inclines with black, damp soils, ranging from 100 mm to > 300 mm deep. Rock exposure is mostly zero, although certain sections have 20% to 30% cover. Canopy cover for shrubs and bamboo 2 m to 3.5 m tall ranges between 20% and 50%. Such cover shades out most other species and, with its dense, tight rhizomal packing, inhibits the root growth of other species. The result is a low herbaceous cover, ranging between 1% and 30%.
The community is characterised by species from Species Group AK, being composed of the monotypic genus of mountain bamboo Thamnocalamus tessellates; the endemic shrub Euryops evansii; and the forbs Alepedia amatymbica and Helichrysum hypoleucum.

The community is dominated by Thamnocalamus tessellatus (Species Group AK). Other prominent species include the tree Leucosidea sericea (Species Group AL), the shrubs Euyrops evansii (Species Group AK) and Myrsine africana (Species Group AL); and the forbs Alepidea amatymbica (Species Group AK) and
Senecio inornatus (Species Group AL).
Thamnocalamus tessellatus forms stands, with poor representation from other species. An average of 23 species per 100 m² was recorded. Shading out by the bamboo, as well as dense rhizome development, which outcompetes other species, may explain the limited development of other vegetation in the community (Gibbs-Russell et al. 1991;Moffett 1997). Such development is the second lowest after the Buddleja loricata-Rhus divericata community 6.2, which is located on large, loose, poorly packed boulders with shallow, thin soils.

DISCUSSION
The results from the phytosociological analysis indicate the woody shrub vegetation to have a variety of plant communities, which are dominated by i) tall and short perennial bunch grasses, in full sun, on moderate slopes, on rocky terrain, with shallow, well-drained soils, which comprise either grassland in transition or established woody/shrub communities (Communities 1, 2 and 3); and ii) trees and shrubs in well-developed shaded stands, on steep slopes, mainly on the southern and eastern aspects, with specialist under-story forbs and grass species (Communities 4 to 8) on deep, damp organic-rich soil.
The Themeda triandra-Watsonia lepida community (Community 1), which constitutes the largest component of the Shrubland vegetation, was found to have the greatest average number of species (32 per 100 m 2 ) (see Table 2). The woody shrub vegetation of the community is possibly an extension of the Western Lesotho Basalt Shrubland (Gd 9; Mucina & Rutherford 2006), which has a similar species composition, with typical species, such as Leucosidea sericea, Rhamnus prunoides and Buddleja salfolia, which are indicative of forest precursors. However, the woody vegetation on Platberg may be more complex than the Western Lesotho Basalt Shrubland described by Mucina & Rutherford. The former represents a biogeographic relictual situation, starting in the Miocene, with climate cooling and the rise and dominance of Grassland (Retallack 1992(Retallack , 2001, with the Western Lesotho Basalt Shrubland unit (Gd 9; Mucina & Rutherford) showing the transition of woody shrubland to grassland. Such a finding is supported by the presence of the C4 grass Themeda triandra, which is adapted to warmer drier conditions (Gibbs-Russell et al. 1991), dominating the northern and western slopes with the shrub Leucosidea sericea dominant/prominent on all slopes throughout Platberg (Table 1). Thus, the zone may be one of tension between the grassland and woody shrubland habitats, in accordance with which the zone or gradient allows for high species diversity patterns (Cowling 1992;Linder 2003). Such may also be the case for the Diospyros whyteana-Euclea crispa community (See Community 4, as represented in Table  1), which is closely related to the Basotho Montane Shrubland vegetation unit (Gm 5; Mucina & Rutherford). The vegetation unit is embedded, or at least closely related to, the Western Lesotho Basalt Shrubland. The rainfall, altitude, and temperature recorded for the study area closely resemble those of the Western Lesotho Basalt Shrubland (Gd 9; Mucina & Rutherford), with the latter shrubland being confined to the Maseru and Mafekeng Districts. The community studied might therefore be regarded as an extension of the vegetation on Platberg.
The lowest species richness is seen in the Buddleja loricata-Rhus divericata community (Community 6) with 18.2 species per 100 m² (see Table 2). Such paucity might reflect the shallowness of the soils occurring on the mobile boulder beds, as well as the high incidence of fire observed in the field.
Studies conducted by Bester (1998), Fuls (1993 and Matthews (1991) also show floristic relationships with Platberg. As discussed by White (1983) and Bester (1998), the high-altitude Afromontane, Altimontane regions of Africa can be regarded as an archipelago-like string of islands. The theoretical model of Macarthur & Wilson (2001) and Hubbell (2001) predicts that the closer the islands are, the greater the alpha diversity. Thus, it might be expected that the studies of high-altitude vegetation for Qwa-Qwa (Moffett et al. 2001) and the Golden Gate National Park (Kay et al. 1993;Roberts 1969) would show a similar species composition and diversity. The species lists for the cool eastern portions of the areas in question show a high degree of similarity with taxa from Platberg. Such a high degree of similarity might have been established before the fragmentation of the Afromontane Podocarpus forests (Mucina & Rutherford 2006). Preez 1992;Du Preez & Bredenkamp 1991b), which is the only other inselberg on which a similar study has been conducted. The Korannaberg is approximately 300 km west of Platberg, in the drier interior of the Eastern Free State. It is also at the lower altitude of 1 881 m (Du Preez & Bredenkamp 1991a, 1991b, and has no basaltic cap. Precipitation is lower, at approximately 550 mm per annum or more (Du Preez & Bredenkamp 1991a, 1991b (Brand 2007).

Other close floristic associations exist with the Korannaberg (Du
In addition, Leucosidea sericea, which is a significant woody/ shrub component on Platberg, is found commonly along streams in the Mountain Zebra National Park (MZNP). The two woody shrubs, Maytenus heterophylla and Diospyros whyteana, are also found in association with the Renosterveld (Pond et al. 2002).

CONCLUSION
No previous vegetation description has been completed for Platberg. The description of the shrubland is part of a larger study that has been conducted into the entire vegetation of Platberg, which has been identified as one of four distinct major communities (i.e. Wetlands, Shrubland, Grassland and Fynbos) occurring on the inselberg (Brand 2007).
The study resulted in the identification of 20 plant communities, which can be grouped into eight major communities, 13 subcommunities and eight variants. A total of 450 species, belonging to 304 genera and 95 families, was identified for the Shrubland. A total of 24 endemic or near-endemic and Red Data species belonging to the Drakensberg Alpine Centre (DAC) and the broader Eastern Mountain Region (EMR) (Carbutt & Edwards 2004 was collected, along with 22 invasive, or potentially invasive, alien species. A species to hectare ratio of 4.37 (43.67 per km²) was calculated, indicating a moderately rich floristic composition.
The shrub community on Platberg is located on the rocky ridgeline or boulder outcrops on the summit, as well as along the benches on the vertical cliffs, at their bases and in gullies, drainage lines and on scree slopes on all aspects of the inselberg. Generally, the woody shrub community is low to medium in height (2 to 6 m), with a predominance of Leucosidea sericea occurring throughout and dominating in communities 1, 2, 6 and 7. Although L. sericea is generally found as a small tree or shrub in the study area, it does reach heights over 6 m in some areas. Though the taller Podocarpus latifolius (M. Cunningham, pers. comm., June 2007) has been reported as growing on the cool eastern slopes of Platberg, none was found during the study. (page number not for citation purposes) (Pooley 2003). The mountain bamboo, Thamnocalamus tessellates, occurs as a disjunct population on the Drakensberg in South Africa, as well as on the mountains, including especially Mount Kilimanjaro, in East Africa. Four species of such mountain bamboo exist, of which there are three genera in east Africa. One genus, Arundinaria tessellate, is synonymous with Thanmocalamus tessellatus. The nearest member of the genus occurs in the Himalayas, suggesting that it evolved there during the formation of Gondwanaland (White 1983). According to Gibbs-Russell et al. (1991), the Himalayan synonym genus is Himalayacalamus.
The Basotho Montane Shrubland (Gm 5) unit is regarded as vulnerable, with the conservation target of 28% being regarded as desirable. Currently, it is only 2% conserved in the Qwa-Qwa National Park section of the Golden Gate Highlands National Park, as well as in the Sterkfontein Dam Nature Reserve (Mucina & Rutherford 2006). The Gd 9 Western Lesotho Basalt Shrubland (Gd 9) is currently not conserved in any reserve, with 16% having probably already been transformed by agriculture (Mucina & Rutherford). On Platberg, where both units are found growing in an interpenetrated union, there is ample opportunity for conservation of such co-joined vegetation units.
The floristic collections and the plant community analysis shows Platberg to be an important centre for plant diversity, with high species richness, and a variety of habitats and complex ecosystems. Accordingly, conservation of the site should be prioritised, with a management plan being developed for such express purpose.
The study described in the present article will provide valuable baseline data on the ecosystems of Platberg. Such data will be incorporated into the management plan for the Platberg Conservancy, as well as be used to augment the larger Maloti-Drakensberg Transfrontier Park Project, the surveys of which are currently being concluded. The data will form part of the biodiversity surveys of the Free State Department for Economic, Tourism, and Environmental Affairs. Such data will assist the Department in setting criteria for protecting and managing unique flora and inselbergs in the province.

ACKNOWLEDGEMENT
Without the generous funding granted by the National Geographic (grant number 7920-05), the current fieldwork and study would not have been possible.

NOTE
Supplementary information for this paper is available from www.koedoe.co.za article #696: Table 1.