A Coupled Vegetation–Crust Model for Patchy Landscapes

A new model for patchy landscapes in drylands is introduced. The model captures the dynamics of biogenic soil crusts and their mutual interactions with vegetation growth. The model is used to identify spatially uniform and spatially periodic solutions that represent different vegetation-crust states, and map them along the rainfall gradient. The results are consistent extensions of the vegetation states found in earlier models. A significant difference between the current and earlier models of patchy landscapes is found in the bistability range of vegetated and unvegetated states; the incorporation of crust dynamics shifts the onset of vegetation patterns to a higher precipitation value and increases the biomass amplitude. These results can shed new light on the involvement of biogenic crusts in desertification processes that involve vegetation loss.