Natural grasslands occur extensively around the globe in areas where there is typically a fairly long dry season. In temperate regions they include the steppes of Eurasia, the prairies of North America, the pampas of South America and the veld of South Africa; in tropical latitudes, savanna is a term applied to a range of tropical vegetation from pure grassland to woodland with much grass (Cox & Moore 1999). Seasonal drought is undoubtedly important in determining the distribution of grasslands, but fire and grazing animals - in removing biomass - often play an overriding role (Peet et al. 1999). The role of grazing animals is so marked that semi-natural grasslands now occur extensively in many areas of the world where deforestation has taken place, both in temperate and tropical latitudes. However, many natural grasslands have been destroyed by cultivation or extensively modified by grazing from domesticated livestock or by the introduction of alien plant species. Similarly, the pressures to increase animal production have led to many semi-natural grasslands being intensified by reseeding, herbicide and fertilizer application. Keywords: climate change, comparative demography, grassland management, insect diversity, invasions, plant traits, population dynamics, population model.