The subtropical thicket biome in the Baviaanskloof
Typical of the Baviaanskloof region, are thicket mosaics. A thicket mosaic occurs when it forms clumps in a matrix of other vegetation zones, e.g. fynbos, succulent karoo. Portulacaria afra (spekboom) typically characterises the subtropical thicket biome. One can recognise it easily on north and east facing mountain slopes where bright green patches occur, usually intermixed with other shrubs. P. afra has an extensive root system which occupies a significant amount of space, and thus keeps loose soil from washing down the steep slopes when it rains. In the early 1900's, there was a great surge in the Angora goat wool industry, and the amount of goats on farms within in the Baviaanskloof increased significantly. This lead to overgrazed lands, accompanied with soil erosion characterized by the formation of erosion gullies and loss of important plant species. Experimentation with P. afra is currently being conducted to see whether planting it back into eroded land, might help to hold back eroding soil due to its extensive root system. The presence of this plant is therefore beneficial for various reasons i.e.:
1) It prevents soil erosion;
2) It is a pioneer species which attracts birds and small mammals. Seeds are transported in their excreta, which aids in seed dispersal and re-introduction of plants on transformed land;
5) It fixes carbon, and therefore plays an important role in the reduction of greenhouse gases in an African context, as it is one of the plants able to fix the most carbon in and arid environments.