黄土高原南部土地利用/覆被变化的土壤侵蚀效应

Effects of Soil Erosion on Land Use and Land Cover Change in Southern Loess Plateau

基于3S技术对黄土高原南部地区土地利用/覆被变化及空间分布格局进行了综合测评,同时应用通用土壤流失方程(USLE)定量研究了不同土地利用方式下的土壤侵蚀效应。研究表明,研究区1980—2005年共有1 123.80km2耕地被用为城镇建设用地,建设用地面积净增了1 238.29km2,林地、草地面积总量变化小,但局部地区流转特征显著;与此同时,该区土壤侵蚀模数从11.54t/(hm2.a)增至13.81t/(hm2.a),1980和2005年黄土沟壑区侵蚀模数的峰值分别为1 708.52和1 584.69t/(hm2.a)。该区域土壤侵蚀效应与土地利用空间格局耦合性较强,林地、草地由于分布区域海拔高,坡度陡,侵蚀强烈,而地势低洼、平坦地区(建设用地、耕地、未利用地)的土壤侵蚀强度小。林地、草地的土壤侵蚀效应由于受到地形因素的影响,对降雨侵蚀因子增强的响应尤其明显。2005年该区林地和草地的平均侵蚀模数分别增加了2.34和7.32t/(hm2.a),并且微度以上侵蚀等级的面积有所增加。

Land use change influences vegetation distribution on the earth surface. Vegetation coverage, tiny terrain, physical properties and chemical properties of soil, as well as erosion resistance, lead to an increasingly complex system for mutual responses to land use/cover changes. The research of soil erosion with regard to different land use types is therefore of great importance. In this study, we implemented the universal soil loss equation to simulate the soil erosion of Southern Loess Plateau based on different land use type with the technologies of 3S. The results showed that the cultivated land and construction land changed significantly, and 1 123.80 km^2 cultivated land has turned to construction land in the past 25 years at southern loess plateau; the construction land has increased 1 238.29 km^2. On the whole, forest and meadow changed little, but they changed significantly in the part of the study area. At he same time, the average soil erosion modulus of southern loess plateau has increased from 11.54 t/（hm^2 · a） to 13.81 t/（hm^2 · a）, the peak value of Southern Loess Plateau were Gully region of Loess Plateau which were 1 708. 52 t/（hm^2 · a）, 1 584. 69 t/（hm^2 · a） in 1980 and 2005. the research also shows that the soil erosion is closely related to the spatial distribution pattern of land cover. In the study area, forest and meadowrs were steeper and higher than construction land, cultivated land and unused land, so the latter（construction land, cultivated land and unused land）ts soil erosion modulus was lower than the former（forest and meadow）. The meadow land and forest were infected by the terrain, which infected the rainfall factors severely. Forest and meadowls average soil erosion modulus were increased 2.34 t/（hm^2 · a） and 7.32 t/（hm^2 · a） respectively. Among all the erosion grade, above the grade of micro-erosionrs area has increased.