Desertification is a process whereby the productive potential of arid or semi-arid lands falls by ten percent or more.
Moderate desertification is a 10-25% drop in productivity, severe desertification causes a 25-50% drop while very severe desertification results in more than 50% drop in productivity and usually creates huge gullies and sand dunes.
It is the phenomenon of change of fertile land into sandy tract. In other words, Desertification leads to the conversion of rangelands or irrigated croplands to desert-like conditions in which agricultural productivity falls.
Desertification is not the literal invasion of the desert into a non-desert area. It includes degradation of the ecosystems within as well as outside the natural deserts.
The Sonoran and Chihuahuan deserts are about a million years old, yet they have become more barren during the last 100 years. So, further desertification has taken place within the desert.
Desertification occurs when the natural vegetation cover is reduced in its cover due to the felling of trees, excessive litter collection, removing branches from plants for feeding the cattle and burning, overgrazing, etc. and the topsoil becomes susceptible to erosion. The removal of the vegetation and topsoil then initiates a number of other problems including-
Increase surface runoff and stream discharge.
Reduction of water infiltration and groundwater recharge.
Development of erosional gullies and sand dunes.
Change in the surface microclimate that enhances aridity.
Drying up of wells and springs.
Reduction in seed germination of native plants.
The effects of desertification can be reversed in many cases. Reversal begins by halting the activities that created the desertification. In many parts of the world, overgrazing and deforestation are the primary factors causing this form of soil degradation. Two other remedies for repairing the effects of desertification are the re-vegetation of the soil surface and the planting of windbreaks.