Encyclopedia of Soil Science
Taylor & Francis
Desert soil surfaces are generally covered with biological soil crusts, a group of organisms dominated by cyanobacteria, lichens, and mosses. Despite their unassuming appearance, these tiny organisms are surprisingly critical to many processes in past and present desert ecosystems and are vital in creating and maintaining fertility of desert soils. They fix both carbon and nitrogen, much of which is leaked to the soils below. They stabilize soils, capture nutrient-rich dust, and can stimulate plant growth. These organisms must tolerate extreme temperatures, drought, and solar radiation, despite having relatively few wet hours for metabolic activity. Under most circumstances, they are extremely vulnerable to climate change and disturbances such as off-road vehicles and livestock grazing. Unfortunately, recovery times are generally measured in decades or centuries.
Belnap, J., 2008, Biological Crusts, in Lal, R., ed., Encyclopedia of Soil Science, Volume 1:1: New York, Taylor & Francis Group, p. 1-4.