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"GRASSLAND: THE MOST THREATENED BIOME IN SOUTH AFRICA" The Grassland Biome is found chiefly on the high central plateau of South Africa, and the inland regions of KwaZulu-Natal and the Eastern Cape. It is one of several great grassland regions in the world, including the steppes of Russia, the pusztas of Hungary, the South American pampas, and the prairies of North America. Frost, fire and grazing maintain the grass dominance and prevent the establishment of trees. Fire is a natural factor caused by lightning and regular burning is essential for maintaining the structure and biodiversity of this biome. Grasslands are unique ecosystems with a rich and often highly specialized animal life, both above and below ground. Formerly native grasslands supported vast herds of ungulates such as blesbok, black wildebeest and springbok. Bird densities range from 50 to 380 birds per 100 ha, and include a wide range of species. South
African grasslands are essentially comprised of a simple, single-layered herbaceous
community of tussocked (or bunch) grasses. It is not generally appreciated that the
majority of plant species in a grassland are non-grassy herbs, most of which are perennial
plants with large underground storage structures, most which can live for several decades.
The Grassland Biome has an extremely high biodiversity, second only to the Fynbos Biome.
At the 1000square meter scale, the average species richness of the Grassland Biome is even
higher than those of fynbos communities, being surpassed only by renosterveld (Table 1).
The majority of rare and threatened plant species in the summer rainfall regions of South
Africa are restricted to high-rainfall grasslands, making this the vegetation type in most
urgent need of conservation. The
Grassland Biome is the mainstay of dairy, beef and wool production in South Africa, and it
contains most of our major river catchments. Grassland occur in some of the best
agricultural soils and is the cornerstone of the maize crop, hence most grassland types
have been radically altered by agronomy (Table 2). Furtermore, species-rich montane
grasslands are currently being destroyed at an average rate of well over 200 square km per
annum by commercial afforestation alone. Transformation of grassland by ploughing and
afforestation is considered irreversible. Urbanization is a major additional influence on
the loss of natural areas – the Witwatersrand is centred in this biome. This biome is
not only one of the most poorly conserved, but there is little potential for conservation
in the future because of its radically altered state. In fact, it is doubtful whether
certain representative veld types within the Grassland Biome can ever be adequately
conserved today, simply because there are no reasonably big areas remaining. TABLE 1 MEAN SPECIES RICHNESS/1000
SQUARE M
TABLE 2 BIOMES OF SA: CONSERVATION
STATUS
Professor Braam van Wyk, PTA University.
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