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Desertification in Lebanon
Desertification is defined as “the rapid depletion of plant life and the loss of topsoil at desert boundaries and in semiarid regions, usually caused by a combination of drought and the overexploitation of grasses and other vegetation by people.”〔(【引用サイトリンク】url=http://dictionary.reference.com/browse/desertification )〕 There is a common misconception that desertification spreads from a desert core. The truth is that land degradation can occur far away from deserts, and the presence of a desert has no effect on desertification. Another misconception is that droughts cause desertification. This is only true if the land had been abused before the drought occurred, and continued to be exploited during the dry season. If the land is well managed however, the land will recover from a drought once it rains again.〔(【引用サイトリンク】url=http://www.unccd.int/ActionProgrammes/lebanon-eng2003.pdf )〕
==Causes==
One of the main causes of desertification is poor soil conservation, which leads to soil degradation. Healthy soil contains organic matter, which is formed when decaying materials are transformed into soil that contains nutrients such as carbon, nitrogen, phosphorus, and sulfur.
Unstable farming methods are also a cause of desertification. Overuse of fertilizers, lack of crop rotation, and poor irrigation practices strip the soil of its nutrients. When the topsoil is depleted of its organic matter, it either becomes too loose or too compacted, which can lead to erosion.
Overgrazing is a large problem and another cause of desertification. Grasses are important in anchoring topsoil in a dryland region. When animals are allowed to graze too much on already dry land, they expose the soil to destructive forces such as thunderstorms and wind.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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