The world is currently experiencing a period of rapid, human-driven biodiversity loss. Over the past decade, numerous metrics for biodiversity have been used to create indicators to track change in biodiversity. However, our ability to predict future changes has been limited. In this study, we use two very different models to predict the status and possible futures for the composition and diversity of ecological assemblages in African tropical grasslands and savannas under land-use change. We show that ecological assemblages are affected more by land use in African grasslands and savannas than in other biomes. We estimate that average losses of assemblage composition and diversity are already between 9.7 and 42.0%, depending on the model and measure used. If current socio-economic trajectories continue (‘business-as-usual’), the likely associated land-use changes are predicted to lead to a further 5.6–12.3% loss of assemblage composition and diversity. In contrast, a scenario that assumes more efficient use of agricultural areas (thus requiring a smaller total area) could be associated with a partial reversal - of as much as 3.2% - of past losses. While the agriculture that causes the majority of land-use change is an important source of economic growth, projections of the effects of land use on ecological assemblages can allow for more informed decisions.