Biological soil crust. The crusts affect soil stability, water infiltration, and soil fertility. For example, their sticky surfaces glue soil particles together, making soil aggregates larger. These larger particles are less susceptible than smaller particles to wind and water erosion. The roughened surface of the crusts also affects the moisture content of desert soils by slowing overland flow of precipitation, thereby increasing water infiltration into desert soils.
Crustal organisms contribute nitrogen and organic matter to ecosystems.
Because of the significant contribution of biological crusts to ecosystem functioning, it is important to understand how environmental factors influence the distribution and abundance of different crustal components. Another facet of USGS research addresses disturbance to crusts. Cyanobacterial fibers are no match for the compressional stress of livestock hooves, off-road vehicle tires, or heavy foot traffic. Recovery of these crusts from such impacts in arid areas can take up to 250 years. Such disturbance may alter the role these organisms play in an ecosystem by influencing how they respond to their physical environment.