Understanding Dryland Landscape Dynamics: Do Biological Crusts Hold the Key?

Understanding landscape dynamics in arid and semi-arid areas is becoming increasingly important, as global change threatens to upset linked ecological and geomorphological systems with potentially serous impacts on livelihoods and environments. Biological crusts (composed of lichens, algae, fungi and bacteria) cover many rock, soil and sediment surfaces in arid and semi-arid areas and provide a key to understanding future dryland landscape dynamics. Such crusts have been found to play a number of key geomorphic and ecological roles, and are identified as important ecosystem engineers and biogeomorphological agents that could be used in environmental restoration. However, they have also been reported to be highly fragile and susceptible to disturbance, and damage to them may result in non-linear consequences for linked dryland geomorphological and ecological systems. This paper outlines the current state of knowledge on biological crusts in arid and semi-arid areas and calls for increased collaboration between geomorphologists and ecologists and better links between studies of biological crusts on rock and soil surfaces.