APPLICATIONS OF BIOGEOCHEMICAL MODELING IN SOUTHERN AFRICA

Biogeochemical modelling is largely concerned with the cycling of carb on, nitrogen, phosphorus and sulphur in the biosphere. It offers a rob ust approach to modelling many aspects of ecosystem function at the re gional scale, since it is not highly dependent on a detailed knowledge of species or organism-level processes. In southern Africa biogeochem ical modelling has been used to provide new insight into the geographi cal distribution and underlying mechanisms of palatable (sweetveld) an d unpalatable (sourveld) grasslands and high-herbivory and low-herbivo ry savannas. It has also been applied to the problem of estimating the emissions of trace gases and smoke particles from vegetation fires in the region, and suggests that the emissions are much lower than previ ously believed. Work in progress relates to the modelling of troposphe ric ozone precursors produced by the soil and plants. Biogeochemical m odelling has the potential to be an integrating tool, drawing together data collected at widely different scales in a way that allows hypoth eses about the working of the biosphere to be rigorously tested.