see also The Cryptogamic
Page of Utah's Capitol Reef National Park.
The brown crust you see as you walk across sandy desert type soils in many places is composed of an association between algae, lichen, mosses, and fungi. Called crypto (from the Greek word for hidden) gamic (marriage) the nature of this soil is obscure to many. But to those in the know this soil is a critical part of the survival of the desert. The cryptogamic organisms help to stabilize the soil, hold moisture, and provide protection for germination of the seeds of other plants. Without it the dry areas of the west would be much different.
Cryptogamic soils go through their own succession,
starting out as a thin hardening of the surface as it drys
out and culminating in a brownish green crust several
centimeters thick. The availability of moisture
determines how much green moss is present relative to
the other species. Although some disturbance is normal
and helps the soil to capture moisture, excessive
disturbance by hooves, bicycle tires and hiking boots has
been shown to destroy the cryptogamic organisms and
their contribution to the soil.