Desertification and Biodiversity

The link between land degradation and desertification has been made abundantly clear in studies conducted in Africa and Australia. A loss of natural vegetation, a loss in soil organic matter and a loss of soil stability contribute greatly to the process. These processes are often interlinked. Vegetation encourages soil stability by providing cover, the binding action of roots, providing root exudates and by the contribution of its biomass to the soil. A loss of vegetation results in a corresponding loss of soil organic matter and stability.

Soil organic matter and soil stability are often linked. A soil that becomes depauperate in its content of organic matter looses the glue that holds soil particles together and becomes easily erodible. The more a soil erodes the more difficult it becomes for the soil microorganisms to glue the particles together. The process is analogous to a spider’s web in the wind. A whole web can withstand the pressure. If one of the threads that anchor it is broken the spider can repair it, but if the rate of damage is slowly increased, there will come a time when the spider cannot repair the damage and the web will be destroyed by the wind.

Every environment has a threshold beyond which damage cannot be repaired by the natural system. In arid and semi arid environments this threshold is very low.”  –Source: groundviews.org

GR:  Naturalists have been concerned about desertification for more than a century.  Though the term has not been in the news very much in recent years, the process has continued wherever people have conducted marginal farming, excessive livestock grazing, watershed deforestation, and other improper land-use practices.  Recently, the term has been showing up more often, and I think we will soon begin to see it regularly seated beside biodiversity as one of the great concerns of this century.

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