Biological soil crusts are communities of cyanobacteria, fungi, lichens, and other living organisms that can bind grains together and reduce the susceptibility of soils to erosion by water or wind. Crusts dominated by cyanobacteria, which occur naturally in many drylands, hold promise as a tool to help control erosion and restore degraded land. To date, however, most studies have focused on how individual cyanobacteria species cultured in a lab, rather than the more structurally complex natural communities, respond to changes in their environment.