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基于1∶10万的1980、2000和2005年的土地利用/覆盖数据和90 m分辨率的DEM数据,采用转移概率矩阵和地形-面积频度方法,分析了1980~2005年长江上游地区不同地形因子条件下的土地利用/覆盖变化。结果表明:1)1980~2000年,草地、林地和农业用地面积变化趋势与2000~2005年相反。后5 a,可能由于退耕的土地出现反弹现象增多,草地和林地面积出现缩减而农业用地面积增加。两个分析时段主要的土地利用/覆盖类型变化趋势类似,包括农业用地向林地和草地的转化,林地向农业用地的转化以及草地向裸地的转化。2)农业用地和城镇用地主要分布于低海拔区而林地、草地则主要分布于高海拔区。低海拔区主要是退耕还林和城市化过程。高海拔区主要是林地的退化消失和草地退化沙化过程。3)农业用地在坡度段10~25°所占面积比例最大。林地用地面积比例随坡度变陡呈现规则递增,城镇用地分布趋势与之相反。近年裸地趋向分布于缓坡区。坡度0~5°的区域主要是草地退化沙化过程;5~10°坡度段主要是退耕还林过程;大于10°的区域造林工程与森林退化并存。4)各种土地利用/覆盖类型对不同坡向的适宜性相差不大。各种坡向上土地利用/覆盖类型变化类似。
Based on 1:10 000 land use / cover data of 1980, 2000 and 2005 and DEM data of 90 m resolution, the transition probability matrix and the terrain-area frequency method are used to analyze the different topography in the upper reaches of the Yangtze River from 1980 to 2005 Land use / cover change under factor conditions. The results show that: 1) From 1980 to 2000, the trend of the change of grassland, woodland and agricultural land area is opposite to that of 2000-2005. After 5 a, there may be a rebound due to the withdrawal of cultivated land, the reduction of grassland and woodland area and the increase of agricultural land area. The main trends of land use / cover types during the two analysis periods are similar, including the conversion of agricultural land to forest land and grassland, the conversion of forest land to agricultural land, and the conversion of grassland to bare land. 2) Agricultural land and urban land mainly distribute in low altitude area and forest land, and grassland mainly distribute in high altitude area. Low-altitude area is mainly the process of returning farmland to forest and urbanization. High-altitude areas are mainly the disappearance of woodland degradation and grassland degradation and desertification process. 3) Agricultural land occupies the largest proportion of the area of 10 ~ 25 ° slope. The proportion of forest land area increases steeply with the gradient, and the distribution trend of urban land use is the opposite. In recent years, nudity tends to be distributed in gentle slope areas. Grassland degradation and desertification processes are mainly in the areas of 0 ~ 5 ° slope, while the 5 ~ 10 ° slope sections are mainly the process of returning farmland to forest. The area of more than 10 ° is associated with forest degradation. 4) The suitability of various land use / cover types to different aspects is not significant. Land use / cover types vary in a variety of ways.