ASSESSMENT OF THE IMPACT OF DEFORESTATION ON SOIL EROSION IN WUKARI, TARABA STATE, NIGERIA

Many studies confirm the relationships between deforestation, agriculture and soil erosion. Deforestation was occurred about two or three decades ago in northern of Iran and replaced with pasture and cultivation. In the present study 7 hydrological stations were selected in deforestation lands. The field survey showed that different types of soil erosion features such as shallow gullies and sheet erosion were observed in deforestation lands in comparison to forest lands. Also, results showed that there is a significant relation between deforestation and the amount of runoff, sediment, TDS and EC. Land use change has a great influence on many soil quality attributes mostly through its effect on soil organic matter. Structural stability of soils is affected by land use, which in turn is positively associated with total organic C content (4). Six et al. (2000) report that cultivation has reduced soil C content and changed the distribution and stability of soil aggregates. Lemenih et al. (2005) demonstrate that soil C and total N contents in the 0–10 cm soil layer declined significantly in 53 years under cultivation compared to the natural forest. The MWD of soil aggregates is significantly greater in the forest and pasture than in the cultivated soils. Cultivation has caused significant decreases in MWD for the 0–10 cm layer (about 61 and 64%) and the 10– 20 cm layer (52 and 62%), respectively for the forest and pasture soils. Similarly, cultivation has resulted in, on an average, a 34% decrease in WSA (water stable aggregation). Soils become more susceptible to erosion as aggregates are disrupted.