WERI FOUNDATION - Deserts and Desertification
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- Daily Motion
WERI FOUNDATION - Deserts and Desertification
The physical characteristics of land undergoing desertification include the progressive loss of the natural, mature vegetation from the ecosystem; the loss of topsoil; increasing salinity of the soil that reduces crop yields and may produce a salty surface crust that hinders the seepage of water into the deeper soil; and an increasing number of gullies or sand dunes as the soil is eroded by wind action. The role of drought is variable and related in part to its duration; a prolonged drought accompanied by poor land management may be devastating, while a shorter drought might not be. As such, drought stresses the ecosystem without necessarily degrading it permanently. Rainfall similarly plays a variable role that depends on its duration, the seasonal pattern of its occurrence, and its spatial distribution. The list of human or cultural influences on desertification includes vegetation loss by overgrazing, the depletion of groundwater, surface runoff of rainwater, frequent burning, deforestation, the influence of invasive non-native species, physical compaction of the soil by livestock and vehicles, and damage by strip-mining. Land management measures to combat desertification focus on improving sustainability and long-term productivity. It is not always possible to return a desertified area to its predesertified condition. As such, mitigating the effects of desertification is best achieved by converting the degraded ecosystem into a new state that can withstand cultural and climatic land-use pressures. Specific measures include developing a resilient vegetation cover of mixed trees, shrubs, and grasses suitable to local conditions. The soil must be protected against wind and water erosion, compaction, and salinization. Water diversions that excessively lower the water table must be reversed, and if possible new sources of water found for human and animal populations. http://WERI-events.org
Daily Motion | April 3, 2009
