Savanna ecosystems cover a substantial percentage of Earth’s land surface area and are economically and socially important (Scholes and Archer 1997; Sankaran et al. 2005; Bond 2008). In addition to harbouring considerable biodiversity, savannas are used extensively by humans, primarily as grazing lands for cattle (Scholes and Archer 1997; Vetter 2005). A growing percentage of the world’s population depends on savannas for their livelihood, and as human populations grow, increasing pressure on savannas could lead to degradation (Vetter 2005).

Grazing can have a strong effect on the condition of the savanna. As fires are fuelled by grass, grass biomass affects both the frequency and intensity of fires in the savanna (van Wilgen et al. 2000). Fire is thought to regulate tree and shrub populations primarily by inhibiting the establishment of fire-sensitive juveniles (Pellew 1983; Higgins et al. 2000).