Managing surface-water in a large semi-arid savanna park: Effects on grazer distribution patterns

Summary ientific and management perception of artificial surface-water provision has swung like a pendulum from being to the benefit of herbivores, to being to the detriment of many vegetation and herbivore species. Using simulations, this study explores in a GIS how the water-landscape may change for water-dependent grazers under different surface-water management policies and climatic conditions in the Kruger National Park, South Africa. The simulations revealed that the addition or removal of artificial water sources in Kruger will only significantly change the water-landscape during drought episodes, emphasising the importance of considering artificial water provision in a spatio-temporal context. More generally, this illustrates how climatic conditions and time-lags can often confound the effects of management intervention in highly variable systems, demostrating the importance of continuous and long-term monitoring for evaluating management actions. Furthermore, it was shown how the wide-scale provision of water suppressed variability in surface-water availability, reducing spatial and temporal heterogeneity that is important for coexistence in, and resilience of, naturally fluctuating, non-equilibrium systems. This was especially evident during drought periods. Considering the results, water provision policies of semi-arid conservation areas supporting large water-dependent herbivore species should explicitly recognise and consequently aim to mimic spatio-temporal variability in surface-water availability.