Increasing elephant Loxodonta africana density is a more important driver of change in vegetation condition than rainfall

The impact of African elephants Loxodonta africana Blumenbuch, 1797 on biodiversity is hotly debated in wildlife management circles with scientists polarised in their views This polarisation is largely due to the individual experiences of researchers We aimed to determine whether elephants or rainfall patterns drove changes in vegetation condition (Normalised Difference Vegetation Index, NDVI) by avoiding a site-specific approach and looking at the issue at a broader scale We used published estimates of elephant population density from 30 sites and recorded the change in density from 1995-1999, from 1999-2002 and from 2002-2006 We also recorded the deviation of annual rainfall from the long-term mean for those periods We modelled these variables against the change in NDVI between periods using mixed effects models We found that elephants were more influential in driving change in vegetation condition than rainfall, and this also occurred at one of our individual test sites where long-term data were available (Kruger) Elephants and rainfall combined to drive change in vegetation condition at our other long-term test site (Amboseli) Management activities (fencing, water provision) may cause the differences between the two long-term study sites Change in productivity driven by rainfall has ramifications for biodiversity, suggesting that elephant derived changes in vegetation productivity (NDVI) also impacts on biodiversity Thus, this study supports previous findings from individual sites that elephants impact vegetation, however there is also a suggestion that these impacts may vary according to management actions