VEGETATION EFFECTS ON SOIL AND WATER LOSSES ON WEATHERED GRANITIC HILLSLOPES, SOUTH CHINA

Deforestation of weathered granitic hillslopes of South China has led to widespread erosion. Using small experimental plots under different vegetation cover, this study examines the effects of land use on soil and water losses. Overland flow increases as the cover conditions change from forest to fern, to tilled soil and, eventually, to bare ground. This is related to the amount of interception and infiltration, both of which decrease as the vegetation cover is reduced. Most slopes consist of an unknown combination of loose materials and weathered granite and the resistance to sediment entrainment cannot be easily determined. The potential sediment yield increases as vegetation cover decreases. Based on empirical relationships between rainfall, overland flow and potential sediment yield, it is possible to demonstrate that soil and water losses can be drastically reduced as vegetation is re-established on these denuded subtropical slopes. [Key words: geomorphology, overland flow, sediment yield, soil erosion, landuse effects, China.]