A role for nonvascular plants in management of arid and semiarid rangelands

A Field Guide to Biological Soil Crusts of Western U.S. DrylandsA Field Guide to Biological Soil Crusts of Western U.S. Drylands

“…The crust's ability to seal the soil surface and reduce evaporation because of its associated high clay and silt concentrations has been repeatedly proposed (Danin 1978;Williams et al 1995a). While some studies show soil moisture is greater under well-developed crusts (Harper and Marble 1988;Meyer and GarciaMoya 1989;Verrecchia et al 1995;Belnap et al 1996), other studies have found decreased soil moisture under crusted surfaces (Harper and Marble 1988).…”

“…The positive relationship between biological crust cover and available soil surfaces has been amply demonstrated (Rogers 1972;Harper and Marble 1988;West 1990;Eldridge 1993b;Johansen 1993). As harsh environmental conditions limit vascular plant cover, greater cover of crusts in lower elevation sites probably occurs in spite of, not because of, these conditions.…”

“…Intense disturbance results in bare soil. Severely, newly, or frequently disturbed soils are generally dominated by large filamentous cyanobacteria (Anderson and Rushforth 1976;Johansen et al 1981Johansen et al , 1984Johansen and Rushforth 1985;Harper and Marble 1988). When disturbance is less severe, less frequent, or some time has elapsed since the disturbance, crusts are generally in some midsuccessional state, with some lichens and mosses present.…”

“…3.2; St. Clair et al 1984;Harper and St. Clair 1985;Eckert et al 1986;Harper and Marble 1988;Lesica and Shelley 1992;Belnap 1993).…”

“…1.1). These communities are referred to as biological soil crusts, or cryptogamic, cryptobiotic, microbiotic, or microphytic soil crusts (Harper and Marble 1988;West 1990). Biological soil crusts are a complex mosaic of cyanobacteria, green algae, lichens, mosses, microfungi, and other bacteria.…”