They are found throughout the world with varying species composition and cover depending on topography, soil characteristics, climate, plant community, microhabitats, and disturbance regimes.
They can be damaged by fire, recreational activity, grazing, and other disturbance and can require long time periods to recover composition and function.
Physical (as opposed to biological) soil crusts results from raindrop or trampling impacts.
They are often hardened relative to uncrusted soil due to the accumulation of salts and silica.
Physical soil crusts often reduce water infiltration, can inhibit plant establishment, and when disrupted can be eroded rapidly.