Microphytic Soil Crusts and Desert Ecosystems Essay -- Soil Soils Agri

Microphytic crud Crusts and Desert EcosystemsCommunities of micro-organisms create crusts on soils throughout semi-arid and arid regions of the world. These microphytic (also called cryptogamic) crusts atomic number 18 formed when all or some of a diverse force of photosynthetic cyanobacteria (blue-green algae), fungi, bacteria, lichens and mosses, bind together with inorganic particles in the first few millimeters of a soil. Microphytic crusts are dominant feature in desert soils they are estimated to represent approximately 70% of desert soil biomass world wide (Belnap 1993). Un-restricted human activity (farming, livestock grazing, recreation) results in the denigration or destruction these bighearted crusts. Many claim that soils and soil mechanisms are at the base of other ecosystem functions (Vitousek, Walker, Syers in Gillis 1994). In order to better understand and manage desert ecosystems, it is meaning(a) to begin to understand how cryptogamic crusts form, what role cru sts play in shaping desert soil properties, and further, how crust removal might effect soil prize and ecosystem stability. Crust Formation It is generally thought that the formation of microphytic crusts begins with the establishment of cyanobacteria or agal communities on the soil surface (Campbell et. al. 1989). There are many opposite types of algae and cyanobacteria which exist in the new crusts, however it is difficult to ascertain which types of organisms are responsible for which processes of early crust formation. Johansen postulates that crusts begin to form when ropy cyanobacteria (as opposed to diatomic and nonfilamentous cyanobacteria or other algae) colonize the surface of soils in a period of moist weather (1993). As cyanobacter... ...ation and Dehydration. Soil Biology and Biochemistry v. 241101-1105.Johansen, J.R. (1993). Cryptogamic Crusts of Semi-arid and Arid Lands of North America. Journal of hycology v. 29141-147. Loope, W. L., Gifford, G. F. (1972). Influe nce of a Soil Microfloral Crust on Select Properties of Soils Under Pinyon-Juniper in Southeastern Utah. Journal of Soil and Water Conservation v. July-August164-165. Metting, B. (1991). Biological Surface Features of Semiarid Lands and Deserts. In Semiarid Lands and Deserts Soil Resource and replenishment , Skujins, J.(edt.). wave Dekker, Inc, New York. pp. 257-293.Skujins, J. Microbial Ecology of Desert Soils. 62-85.West, N. E. (1991). Nutrient Cycling in Soils of Semiarid and Arid Regions. In Semiarid Lands and Deserts Soil Resource and Reclamation , Skujins, J.(edt.)Marcel Dekker, Inc, New York. pp. 295-327