Vegetation dynamics in the face of a major land-use change: a 30-year case study from semi-arid South Africa

Abstract

Although wildlife production is widely considered beneficial for semi-arid environments, few studies have reported on the long-term environmental effects of converting from livestock production to game ranching. Asante Sana Game Reserve in South Africa was stocked with domestic livestock for centuries. However, after 1996 game ranching was adopted in the reserve. We investigated the long-term (1987–2017) spatial and temporal change in vegetation productivity and type on the reserve using Landsat multispectral data and soil adjusted vegetation index (SAVI), and explored the relationship between changes in vegetation productivity and the potential drivers. The results show that while Thicket has decreased overall, it has expanded into parts of Grassland and Shrubland, and Bare-ground has expanded into parts of Shrubland and Thicket. Overall vegetation productivity increased over time, with the greatest increases in Thicket and Grazing lawn and the lowest in Shrubland and Bare-ground. Changes in rainfall, fire and stocking rates were all significant predictors of the observed changes in vegetation productivity, but rainfall had the strongest effect. This research highlights some of the complex responses that arise in semi-arid vegetation when domestic livestock production is replaced by game ranching, and points towards key issues that can be addressed by management.

Keywords: land-use change, remote sensing, semi-arid rangeland, vegetation index, wildlife impact