More is not necessarily better: The role of cover and spatial organization of resource sinks in the restoration of patchy drylands

A low-cost restoration action in patchy drylands worldwide is the installation of obstructions (hereafter, resource sinks) to break runoff pathways and retain resources. Field-works have studied how the effectiveness of this action depends on the materials installed. However, the influence and effectiveness of the cover and spatial organization of resource sinks have not been widely investigated. In this work, we use a well-known dryland model to study how different initial cover and spatial organization of installed resource sinks affect the recovered ecosystem. In agreement with field-work studies, our results confirm that the installation of resource sinks can restore degraded drylands that would not recover naturally. More importantly, a very small cover of resource sinks was sufficient to trigger vegetation recovery, while a high cover would lead to complete failure. Higher plant densities were reached when distribution and cover were similar to that of spatial self-organized vegetation in the reference healthy system (i.e., regular spatial distribution in our study system). Given the effectiveness of low cover installations, suggested by our work, combined with the low-cost materials needed, resource sinks have the potential to be a key contributor to the large restoration efforts needed to achieve land-degradation neutrality, particularly in developing countries.