Spatial interactions and resilience in arid ecosystems.

We present a mathematical analysis of the consequences of spatial interactions between vegetation patches by means of water flow for the functioning of arid systems. Our model results suggest that spatial exchange of water improved the resilience to disturbances and increased the resistance to human-induced loss of cover. Furthermore, spatial exchange of water allowed vegetation to persist at lower rainfall levels compared to systems that lack spatial interactions. Our analysis stresses the general importance of spatial interactions for the functioning of ecological systems.