IMPACTS OF CLIMATE CHANGE
ON PLANT DIVERSITY IN SOUTH AFRICA

BIOMES AND HOTSPOTS

The vegetation of South Africa is so rich and varied that, when discussing plant distribution, it is convenient to refer to broad ecological regions. We call these regions biomes, and they are characterised by particular climates and vegetation types. Ecologists have described seven South African biomes, namely Desert, Forest, Fynbos, Grassland, Nama-Karoo, Savanna and Succulent Karoo.

• The Fynbos and Succulent Karoo biomes are found in the western parts of South Africa where rain falls in winter.
• Nama-Karoo vegetation, with its typical hardy bushes and grasses, covers much of the arid interior.
• In the summer rainfall areas, Grassland dominates much of the highveld where frost restricts the growth of trees.
• The coastal and lowveld regions are warm enough in winter to support Savanna vegetation.
• The smallest biomes are the Forest Biome in the southern Cape and a tiny area of true Desert in the extreme north-west of the Northern Cape.

According to climate models, within 50-100 years the biomes as we know them will have been reduced to 35-55% of their present area. Climatic conditions in the rest of the country will be unlike anything experienced today.

From the point of view of plant conservation, one of the greatest challenges is how climate change may affect plant biodiversity 'hotspots'. These areas are unusually rich in species but are highly threatened by human activities. Hotspots may also have a number of endemic species, which have such restricted natural distributions that they are found in that particular area and nowhere else on Earth!

One such global hotspot is the Succulent Karoo Biome, which has the richest succulent flora in the world. These plants live on the edge of survival, completely dependent on low but fairly reliable winter rainfall. If the climate of this region becomes any drier, the effects on the entire biome will be devastating.