Literature Review Literature: Global Land Degradation

CHAPTER TWO
LITERATURE REVIEW
2.1 Global Land Degradation: Definition and Introduction There are various kind of definitions of land degradation as revealed in the review literature (GLASOD1988; UNCCD 1994; Hill et al. 1995; Bai et al. 2008). All these definitions show a condition in which the land seems to loss its capacity to provide the intended use of services. Some of the common definitions of land degradation include the one presented by Reynolds (2001) which states that: ‘land degradation is a persistent reduction in the biological and economic productivity of terrestrial ecosystems, including vegetation, soils, other biota, and the ecological, hydrological and biogeochemical processes that operate therein’. Land degradation created a major threat to the world’s ability to meet the increasing demand for food and other services of the environment. It is a complex process which involves the interaction of the changes of biological, physical and chemical properties of the vegetation and soil (NRC 1994). Land and also soil degradation can be recognized and described through the physical, biological and chemical changes from some ideal state created by natural or man-made influences. Land degradation is the long-term loss of function and productivity of ecosystem which is caused by disturbances from the land which it cannot recover without human aid (Bai and others 2008). According to Muchene 2008, land degradation occurs gradually and cumulatively and then