Cause And Effects Of Soil Deforestation

INTRODUCTION

Soil degradation is a most serious environmental problem in many countries. One of the most important driving forces of soil degradation is human activities. Human activities often influence the natural processes in soil. According to (Doran et al., 1998; Cavelier et al., 1999; Chew, 2001; Liu et al., 2002; Johnson and Lewis, 2007; Seeger and Ries, 2008) defined deforestation as a perceptible aspect of human activities in environment. This change has many effects that can appear through the reduction of chemical and physical qualities of the soil resources. FAO (1993) further stressed that soil degradation is the sum of geological, climatic, biological and human factors which lead to the degradation of the physical, chemical

Such a condition is exceptional and there is evidence that even under natural conditions nutrient losses occur Stoorvogel et al., (1997). Deforestation is a drastic land cover change and the clearing and burning of the natural forest has a large impact on soils stated by Lal, (1986). All deforestation studies find considerable changes in soil physical and chemical properties stated by Lal, 1986; Ghuman and Lal, 1991; Veldkamp, 1994; Juo and Manu, (1996). Most studies indicate that the abrupt transition from natural climax vegetation to a managed system by man has several short-term effects on soil properties. The most important on-site effect is the loss of organic matter causing a reduction in nutrient stock, CEC, and structure

Lal, (1986) stressed that another effect that occurs in deforested sloping areas is erosion. This is often mentioned as the main cause for soil degradation. Burning of biomass and debris reduces Nitrogen and Sulphur stocks, while deforestation with heavy machinery may cause soil compaction and erosion according to Hulugalle, (1994). Although it is generally accepted that the conversion of forests to cropland is associated with a decrease in soil fertility, there are few data on the long term effects of this land use. Initially, soil fertility can increase following deforestation, especially when the forest is burned rather than logged reported by Uhl (1987).Conversion from forest to new forest has smaller long term dramatic effects on soil organic Carbon and bulk density compared to conversion from forest to cropland. It matters whether forest is converted to cropland with annual crops (e.g. maize, cassava, or soy beans), perennial crops (e.g. oil palm, cocoa, or rubber), or forest plantations. The conversion of forest to perennial crops usually results in lower levels in the rates soil fertility decline because – to some extent - these systems mimic the forest cover (Hartemink, 2005b). Nonetheless, both erosion and soil chemical changes can be significant in the early stages of crop development when the canopy is not closed and the