**7.2.3 Wind**

On Platberg, Asteraceae has the greatest numbers of genera and species, however grasses are the most dominant plant group with Cyperaceae the third most abundant. Wind dispersal is an important mechanism of pollination for grasses (Gibbs-Russell 1991) and for sedges (Gordon-Grey 1995). Wind pollination is also important for *Cliffortia* and *Anthospermum* fynbos species (Hillard & Burtt 1987), both of which are abundant on

Biogeography of Platberg, Eastern Free State, South Africa:

Carbon (Mucina & Rutherford 2006).

grass and soil ecosystems (Retallack 2001).

Westfall 1994).

Ferrier 2002).

Links with Afromontane Regions and South African Biomes 131

change, CO2 level fluctuations, fire and grazing are all responsible for the present day species richness and diversity recorded on Platberg and its parent vegetation of the Drakensberg. The Grassland Biome in South Africa is second largest of all eight Biomes (354 593.501 km²) after the Savanna Biome (412 544.091 km², Mucina & Rutherford 2006), with

Between 30–55% of the Grassland biome has already been transformed with only 5.5% protection. Grassland is under significant threat of continual transformation, the most severe is ploughing, which disrupts the soil and releases not only moisture, but also nutrients and

Fig. 8. Platberg showing tracks of the major floristic influences (modified from Rutherford &

Undisturbed grassland provides a significant Carbon sink, and should thus be given priority status for conservation, which should include both the above ground and belowground

Historically in South Africa, areas for conservation were not selected primarily for ecological reasons until the mid 1970's (and then only in the Cape), but were rather based on other criteria, such as national strategically protection of the watershed around dams; fragmented forest areas to protect the water sources higher up in the mountains, or politically determined boundaries such as the Kruger National Park. It was only between 1971 and 1982 in the Cape, that a few wilderness areas were established for scientific research in natural ecosystems, aesthetic values they engendered and physical and spiritual opportunities they afforded (Rebelo 1992). Biogeographical considerations such as fynbos being 'islands' surrounded by forest were used as well as critical plant population size and habitat. These parameters plus total land surface were selected in determining conservation areas. It was found that for mountain areas, the minimum statuary size for reserves should be at least 10 000 ha (Rebelo 1992). Human population growth and increased urbanisation are seen as two major threats to natural ecosystems, with the implications for conservation of the effects of unrestricted human population growth being considered (Rebelo 1992;

both Biomes providing an enormous sink for Carbon as well as climate amelioration.

Platberg as well as the DAC. This long-distance dispersal by wind allows for crossing mountain valleys, from one isolated peak or inselberg to another.

Pollination by wind allows for gene flow between disparate areas (Cowling & Lombard 2002), which have different geology, soils, moisture availability and climate (Burke 2001, 2002; Linder 2003). The effects of wind to influences floristic composition and species richness over long distances and connect different regions is seen on the granite inselbergs in West African (Porembski et al., 1996), Namibian (Burke 2001), and Mulanje (Burrows & Willis 2005), basalt lavas of Platberg (Brand et al., 2010), the Drakensberg (Mucina & Rutherford 2006), and quartzite of the Cape Fold Mountains (Linden 2002).
