Nature Photos

"Biological soil crusts (BSCs) are an intimate association between soil particles and cyanobacteria, algae, microfungi, lichens, and bryophytes (in different proportions) which live within or on top of the uppermost millimeters of soil. These communities have been known by a variety of names, including cryptobiotic, cryptogamic, and microbiotic soil crusts." -from A Field Guide to Biological Soil Crusts of Western U.S. Drylands by Roger Rosentreter, Matthew Bowker, and Jayne Belnap, US Government Printing Office, 2007

Soil crusts are environmentally important, contributing nitrogen and other nutrients to the soil and preventing erosion. They have been heavily impacted by livestock grazing, habitat alteration, and off-road travel.

The photos below show some examples of soil crusts. More photos can be found in the Lichens and Mosses sections.

Image 1. A small soil crust mound in southwestern Colorado. This one consists mainly
of cyanobacterial filaments that hold the soil together while the bare soil around it has eroded.

Image 2. Small soil crust mounds in southwestern Colorado. They consist mainly
of cyanobacterial filaments that hold the soil together while the bare soil around them has eroded.

Image 3. Tiny filaments of the cyanobacterium, Microcoleus sp., barely visible on soil in Idaho.

Image 4. Filaments of the cyanobacterium, Nostoc commune, on soil in Idaho.

Image 5. A small soil crust mound in southwestern Colorado, held together by a lichen, a species of Psora.
Species of Psora most typically grow on soil; some other examples are below.

Image 6. Psora crenata, on soil in Big Bend National Park, Texas

Image 7. Psora decipiens, eastern Arizona

Image 8. Psora icterica, in the hill country of Texas

Image 9. Psora pseudorussellii, in the hill country of Texas

Image 10. Toninia sedifolia, another soil lichen, from the south rim of the Grand Canyon, Arizona

Image 11. Bryum argenteum, a moss on soil in southern Idaho.

Image 12. Riccia trichocarpa, a moss on soil in southern Idaho.

Image 13. Syntrichia ruralis, a moss on soil in southern Idaho.