Changes in land use in semiarid savannas to intensive cattle ranching
have been widely equated with changes in vegetation communities, notably
bush encroachment. Increased availability of soil water in the subsoil has been
assigned as both a cause and a consequence of this ecological change. Here we
investigate the applicability of this association in an intensively grazed area of
the Kalahari sandveld, Botswana. Studies show that no significant differences
exist between profile patterns of soil water availability, or hydraulic conductivity and field capacity, between bush dominant compared to grass-dominant
sites. Vegetation changes are determined predominantly by interactions of
grazing levels, fire occurrence and natural rainfall variability. Pastoral
management strategies should therefore account for the interactions between
these variables to prevent convergence of bush dominant areas. Soil water
movement in Kalahari soils remains largely restricted to the upper 2-3 m of the
soil implying that groundwater recharge is negligible and that important consideration of the extent of groundwater resources is required