Effects of Land Use/Land Cover Changes on Rocky Desertification-A Case Study of a Small Karst Catchment in Southwestern China

Based on extraction of environmental information from lake (reservoir) sediment, this paper carried out systematic studies on effects of land use/land cover changes on soil erosion in last 40 years in Shibanqiao catchment of Guanling County, located in the southwest of Guizhou Province. Seven sediment cores were retrieved and analysis of activity of 137Cs of sediment samples was undertaken. The information of soil erosion in each phase was deduced, and then integrating it with land use/land cover changes in corresponded phase, the author took a further step to interpret the effects of land use/land cover changes on soil erosion. Such conclusions were drawn: (1) the rate and amount of soil erosion is related not only with land use/land cover regime but also with whether there are abundant erodible sources provided for erosion. (2) During 1960 to 1978, in the beginning of land use change, naturally selective erosion was dominant. Then the percentage of surface soil erosion increased, and became dominant in the subsequent phase. Soil erosion was decreased but rocky desertification expanded in a higher rate. So it can be deduced that there was a lag between the development of rocky desertification and soil erosion;(4) The accelerated soil erosion resulted from the stir of soil during the implementation of ecological engineering was detected between 1990 to 2002, in view of which, a suggestion was put forward in this paper that ecological constructions and engineering towards water and soil maintenance should pay attention to the problem of soil erosion followed, especially should avoid the stir of soil. (C) 2011 Published by Elsevier Ltd. Selection and peer-review under responsibility of RIUDS