Elephant-induced landscape heterogeneity change around artificial waterholes in a protected savanna woodland ecosystem

Abstract

Abstract In protected areas, establishment of artificial waterholes has been hypothesised to result in increased elephant (Loxodonta africana) densities around these waterholes which would in turn result in changes in landscape heterogeneity. To test this hypothesis this study first tested the relationship between waterhole distribution from remotely sensed waterholes and elephant density in Hwange National Park (HNP), Zimbabwe. The study tested using the coefficient of variation of the Normalised Difference Vegetation Index (NDVI CoV) the short-term effects of varying elephant densities on vegetation heterogeneity change at the landscape scale. This study also tested the relation between artificial waterholes and surrounding landscape configuration and composition change and in addition assessed the potential influence of spatial variability in rainfall on landscape configuration and composition dynamics. Results indicate that elephant density increases in response to the increase in concentration of late dry season waterholes. Results indicate that there is no relationship between elephant density and vegetation heterogeneity change at the seasonal scale (short-term). This could be attributable to differences in sensitivity and response of different vegetation types to elephant browsing even the variable foraging preferences of elephants at the landscape scale regardless of elephant occupation. Findings of this study imply that in the long term, maintenance of artificial waterholes results in a decrease in woody vegetation structural heterogeneity through conversion of woodlands to coppiced bushland in areas with high artificial waterhole density. Findings of this study also show that landscape heterogeneity change is not significantly related to the existing north-east to south-west gradient of decreasing rainfall in HNP.