A field guide to biological soil crusts of western U.S. drylands: Common lichens and bryophytes
Bureau of Land Management
U.S. Government Printing Office, Denver, Colorado
Biological soil crusts are the community of organisms living at the surface of desert soils. Major components are cyanobacteria, green algae, microfungi, mosses, liverworts and lichens.
Rosentreter, R., Bowker, M., and Belnap, J., 2007, A field guide to biological soil crusts of western U.S. drylands: Common lichens and bryophytes, Denver, Colorado, U.S. Government Printing Office, 104 p.