Effects Of Land Use/Cover Change On Soil Erosion-A Case Study Of Hetian Region

LUCC has been one major focus in global environment research. Soil erosion, as one of the major environment effects caused by LUCC, has been severely limiting the sustainable land use. Therefore, the relation between the LUCC and soil erosion becomes a new focus in these two fields. The Changting County is one of the counties that get the most serious soil erosion in the granite region of south China. There have been many soil erosion studies in scale of this whole county. However the whole-county scale research couldn't provide the individuality on some micro-scale featured areas. This paper intends to study the soil erosion affected by LUCC by selecting a typical smaller-scale region from the whole-county scale region, hence to provide a proper measure against soil erosion and for the sustainable land use development.Since the soil erosion effects occurs mostly in the middle of Changting County, this study chose Hetian area (including Hetian, Sanzhou and Zhuotian three town region), which have been taken measures against soil erosion, as the research area. After processing their SPOT5 data in 2000 and 2007 as well as statistics of the land use and coverage data with soil erosion information by RS and GIS methods into vegetation coverage map and soil erosion map, we compared the differential features on LUCC and soil erosion map by the two periods, and, analyzed the relationship between the LUCC and soil erosion. Furthermore, we select the sample spots that varied obviously in LUCC and soil erosion and run field investigations on the biological diversity and solutions of these sample spots to verify the soil erosion affected by LUCC. After that, the mode of vegetation recovery solution of the soil erosion area is also discussed by result.Below are the results and the conclusion of this study:(1) Comparing with year 2000, the LUCC features in year 2007 shows that, there is an area increase in the forestland, a decrease in the open forest, and there is a transfer from the forest land to the open forest. High vegetation coverage increases, the modes and low vegetation coverage decreases, and there is a transfer from the modest and low vegetation coverage to the high vegetation coverage. The LUCC shows an increasing on the vegetation coverage rate after years of managing. (2) Comparing with year 2000, the LUCC features in year 2007 shows that, there are decreases in the soil erosion area, soil erosion rate and soil erosion intensity. There is a transfer from the Heavy Erosion to the Modest Erosion category. Generally, the soil erosion area and the soil erosion intensity are decreasing as the conservation of soil and water proceeds.(3) There may be positive or negative effects that LUCC causes to the soil erosion. The variation in the use type of forest land effects mostly to the soil erosion by negative correlation, lower vegetation coverage effects the soil erosion by negative correlation before taking measures, and the high vegetation coverage effects the soil erosion by positive correlation after taking measures.(4) The vegetation coverage level, biological diversify and the forest stand structure are interactional. They benefit each other to stabilize the ecology system, hence increases the reservation of water and soil of the land. Otherwise, it seeds the soil erosion process. After taking management measures for several years, the vegetation coverage level and the biological diversify index of Hetian region obviously improves, and the forest stand structure grows complex, the soil erosion area and the soil erosion intensity is decreasing as the conservation of soil and water proceeds.(5) Since 2000 in the Hetian area, we have taken account the regression recession procedure of the vegetation community from bare land, sod, the Pinus massoniana and shrubbery, Broadleaf and Coniferous Trees, to the mixed of broadleaf evergreen trees. We also adopt the mode combining the tree, shrub and herb plants into the vegetation recovery and definitely, these measures worked for the ecological recovery.(6) The management measures against the soil erosion should define the small watershed as unit, and take the soil erosion spot as an object, to choose proper vegetation species and apply corresponding recovery mode according to the variant soil erosion environment, intensity and relative succession patterns of vegetations. Several recovery modes could be applied to variant soil erosion area at the same time, or could be applied to one single area at different time.