Diversity without complementarity threatens vegetation patterns in arid lands

Patterns found in mixed communities including grass, shrubs and trees function as natural water-harvesting systems in arid and semi-arid regions throughout the world. Furthermore, self-organizing vegetation patterns may be indicators of environmental shifts in climate and land use change scenarios. Therefore, net facilitation, leading to resource concentration within vegetation patches, should be imitated and preserved. This study analyses the ecological feedback between niche adaptation of similar band-forming species, and the environment in which species thrive. A minimal model for two coexisting species and the soil moisture balance was formulated to improve our understanding of the effects of species differentiation on the dynamics of plants and resources on single pattern and landscape scales. The model outcomes suggest that pattern-forming-species communities arise as a result of niche differentiation (driven e.g. by evolutionary changes), whereas similar adaptation strategies to cope with harsh conditions may lead to impoverishment of environmental resources and loss of vegetation cover and diversity.