The reduction in canopy cover of the Seronera woodlands since the mid- 1960s can be largely attributed to the destruction of mature Acacia tortilis trees by elephants. The development of the tree regeneration that has colonized the gaps in the mature canopy is being suppressed by giraffe browsing and periodic burning. A simple model is presented which simulates these impacts upon the dynamics of the A. tortilis population. Height-specific impact rates of these three agents are quantified. Between 1968 and