The long-term effects of small-scale spatial heterogeneity of livestock grazing on vegetation dynamics were studied with a grid-based model of major life forms of savanna vegetation. Based on southern Kalahari ecology, the model includes stochastic life-history variables, resource competition for soil water, and biomass production for annuals, perennial grasses and shrubs. Keywords: grid-based model, Kalahari, livestock grazing, shrub cover dynamics, vegetation change.