Biological soil crust in shrub-steppe near Hammett, Idaho.

Although at first glance the land in this region might seem barren and too harsh to support life, there are many communities of organisms that survive and thrive in such an environment. Soils in arid regions are full microscopic life which contribute to the formation of soils and the ecosystem's health. Microbial communities play a pioneering role in soils, forming a surface layer - called biological soil crust or cryptobiotic crust, helps to stabilize the soil and support other populations of life. The organisms which contribute to the formation of biological soil crusts include cyanobacteria, lichens, mosses, liverworts, green algae, microfungi, and bacteria.

If the soil remains undisturbed in arid regions, the cryptobiotic crust can cover much of the spaces between vascular plants. This crust can help to retain moisture the upper layer of soil, help prevent erosion, and provide nutrients for plants. Soil crusts are also thought to inhibit seed germination of a number of weedy species including cheatgrass (Bromus tectorum).