The Role of Biological Soil Crusts on Desert Sand Dunes in the Northwestern Negev, Israel

Biological soil crusts are important microphytic communities and significantly influence both structure and processes within the ecosystem. They are built up from cyanobacteria, green algae, fungi, mosses and lichens. Various crust types could be found, depending on dune slope aspect and dewfall availability. In the sand dunes of the northern Negev they cover large areas and stabilize the sand surface against wind and water erosion. Free-living and symbiontic cyanobacteria are capable of nitrogen fixation and are important nitrogen sources in the desert sand dunes. As biological crusts enhance the surface stability and soil fertilization, they are to be considered a key factor in the protection of arid and semiarid ecosystems and, thus, in combating desertification in terms of sand dune remobilization.