Cryptobiotic

Cryptobiotic refers to cryptobiotic crusts, a form of biological soil crust found in arid and semi-arid regions. These crusts consist mainly of cyanobacteria, with contributions from algae, lichens, mosses, and fungi, living in the topsoil. They form a thin, cohesive layer that binds soil particles and gives the surface a distinctive color. Cyanobacteria secrete mucilage that glues particles, some species fix atmospheric nitrogen, and the crust helps trap moisture and reduce erosion. The organisms can endure extreme drying and later resume photosynthesis after rainfall.

Cryptobiotic crusts occur worldwide in deserts and drylands, with well-known examples in the Mojave, Sonoran, and Chihuahuan Deserts of North America, as well as arid regions of Africa, Asia, Australia, and South America. The exact composition varies by climate and moisture, but cyanobacteria tend to dominate in younger crusts, while lichens and bryophytes become more prominent as crusts mature.

These crusts are highly sensitive to disturbance. Vehicle travel, grazing, off-road recreation, mining, and development can break the crust and greatly increase erosion and dust. Recovery is slow, often taking decades; prevention and protection are essential. Management emphasizes minimizing disturbance, using designated routes, and promoting natural recovery; restoration attempts are limited and typically focused on preventing further damage.