VIEWS: 95 PAGES: 6 POSTED ON: 11/9/2012
Desertification Desertification is the process by which a productive dryland area is degraded to the point that it becomes unproductive desert land. In most cases desertification is caused by human activities. The most common practices that lead to it are: Over-cultivation Overgrazing Deforestation Inappropriate irrigation techniques Dryland areas have very delicately balanced ecosystems that have evolved over thousands of years so that the animals and plants in those areas have adapted to seasonal water shortages. The desertification process usually starts when the cover of native plants is removed from dryland areas. People may do this to clear the area for agriculture, or they may have cut down all the trees and shrubs to use for firewood or building materials. With the plant life gone, the soil loses its moisture more quickly and becomes more vulnerable to erosion. As the soil dries out, it presses together, or compacts. When this happens the soil becomes impervious, that is, it loses the ability to absorb what little rain it does receive. New vegetation cannot establish itself in such an area, and without the necessary organic material and water, the soil cannot recover its fertility. On irrigated land, the soil may become sterile or lifeless because the repeated irrigation causes a buildup of salts to such a level that plants can no longer survive. The consequences of desertification are very serious. As more and more land changes to infertile desert, the people who live there are forced to seek new places to grow their food. In the meantime, they are subject to starvation and malnutrition. Deserts can contribute to weather changes by raising temperatures and lowering humidity levels. Biodiversity suffers, as living organisms face peril, with food and shelter disappearing. Read pages 120-123 Once you finish reading, answer the assigned questions below. a) What are the sequence of events that typically lead to desertification? b) What are the consequences of this process?Briefly explain. Once you have answered the above two questions, turn to pages 126 and 127 in your text and answer questions 11, 12 and 13. Write in complete sentences.
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