What is desertification    
(11/4/2013)



Desertification is a type of land degradation in which a relatively dry land region becomes increasingly arid, typically losing its bodies of water as well as vegetation and wildlife. It is caused by a variety of factors, such as climate changeand human activities . Desertification is a significant global ecological and environmental problem. The immediate cause is the removal of most vegetation. This is driven by a number of factors, alone or in combination, such as drought, climatic shifts, tillage for agriculture, overgrazing and deforestation for fuel or construction materials. Vegetation plays a major role in determining the biological composition of the soil. Studies have shown that, in many environments, the rate of erosion and runoff decreases exponentially with increased vegetation cover. Unprotected, dry soil surfaces blow away with the wind or are washed away by flash floods, leaving infertile lower soil layers that bake in the sun and become an unproductive hardpan. Alternatively, recent research has suggested that the movement and migration of large herds of livestock and wildlife has an integral role in the preservation of vegetation and soil fertilization, and that the removal of livestock and wildlife (largely by human influence) has been the main driver of increasing desertification.