Bushclump-grass interactions: influence of bushclumps on their local environment in a south-east African savanna

Abstract

The interaction between multi-species bushclumps and the herbaceous layer was investigated in a mesic Eastern Cape bushclump savanna. Bushclumps had a moderating effect on their microclimate when compared with the open grassland: lower maximum and higher minimum temperatures. higher humidity and 80-90% reduction in irradiance. Soils beneath bushclumps were more fertile than grassland soils with greater organic carbon. P, K and CEC. The importance of bushclumps in maintaining and recycling nutrients, especially on sandier soils, was highlighted as mesic savannas are threatened by complete bush clearing. Bushclumps were characterized by a sparse shade-tolerant herbaceous layer dominated by Panicum maximum and Helictotrichon capense which contributed little to grazing capacity. Grass production was greater in the grassland on the south-facing side of bushclumps than on other aspects. The size of the bank of woody seeds and seedlings beneath bushclumps, but not beneath grasslands. indicate a likely rapid re-estab/ishment of woody individuals following bush clearing.

African Journal of Range & Forage Science 16(1 ): 32-43