Sunday, March 2, 2014

Biologic Soil Crusts

When I was out west on one of my hikes, there was an interpretive sign about soil crusts.  The sign asked hikers to stay on designated trails to prevent damaging the biologic layer that protects the soil.  I've never really heard of this before, so I decided to do a blog posting on the subject.

The reason why I was not familiar with biologic soil crusts is that they are the community of organisms living primarily on  the surface of arid and semi-arid regions. 

The ground in arid regions is not covered with the dense forests that I am used to.  Instead, complex micro biotic communities develop into networks on the surface and just under the surface.  Lichens of various colors spread like a layer of stucco over the soil and rocks.  Beneath this layer algae, cynobacteria, and other organisms wrap around the sand grains.  Together this biologic community forms a net that protects the soil from erosional forces.

According the the website, biologic soil crusts develop in the "Great Basin, Colorado Plateau, Sonoran Desert, and the inner Columbia Basin. Crusts are also found in agricultural areas, native prairies, and Alaska. Outside the United States, crusts have been studied in the Antarctic, Australia, and Israel, among other locations. In fact, micro biotic crusts have been found on all continents."

Crusts are well adapted to severe growing conditions, but cannot survive disturbances from livestock grazing, hiking, biking, and off-road driving.  So if you are visiting these areas with a biologic soil crust:  please stay on designated trails.


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