ABSTRACT
In drylands, tundras, cold uplands, wherever land is periodically deprived of adequate moisture, where soils are infertile, or poor drainage leads to saline conditions, crusts or pans, if vegetation is present it will probably be easy to disturb and slow to reestablish. When fuelwood is scarce peasants or merchants collecting for urban consumers may so damage treecover that people have to gather animal dung and crop residues, accelerating soil degradation initiated by thinning the woody vegetation. Soil degradation is generally a component of desertification; however, it may take place without leading to particularly desert-like conditions. Salinization and alkalinization are major causes of soil degradation. Surface water flow causes much soil erosion, subsurface flow can affect surface flows. If cultivation of eroding land ceases, if there is some other landuse change, the system might move toward more or less erosion. Many irrigation management authorities regulate water supplies to growers to help avoid over-irrigation and the likely consequences of waterlogging and salinization.
