基于Landsat TM/ETM数据的锡林河流域土地覆盖变化

根据1987年、1991年、1997年和2000年4期Landsat TM/ETM影像的土地利用／土地覆盖分类结果，运用地理信息系统空间分析方法，分析了内蒙古林河流域1987－2000年间各土地利用类型及草甸草原、典型草原、荒漠草原的数量变化和空间变化特征。分析结果显示，锡林河流域土地利用／土地覆盖变化的主要特征为草甸草原、典型草原面积的大幅减少和荒漠草原、农田和沙漠化土地面积的大幅增加及城镇的扩张。其中面积增加最大的是荒漠草原，增加了2328km^2；相当于1987年荒漠草原面积的56％。农田和城镇面积逐年增大，分别从1987年的114.3km^2和25.2km^2增加到2000年的332.1km^2和43.6km^2。面积减少最多的是羊草＋丛生禾草、羊草＋杂类草等优良高产温带典型草原类型，共减少2040km^2。草甸草原面积亦呈逐年减少的趋势，从1987年的1103km^2减少到2000年375km^2，面积减少了65.9%。农田、沙化地及城镇等非草原土地利用类型面积增加了62.5%。

Quantifying Land Use and Land Cover Change in Xilin River Basin Using Multi-temporal Landsat TM/ETM Sensor Data

The land use/land cover change of Xilin River Basin in th e past two decades was investigated through land use/cover classificati on of four sets of Landsat TM/ETM images acquired on July 31, 1987, A ugust 11, 1991, September 27, 1997 and May 23, 2000, respectively. Primarily , 15 sub-classes land cover types were recognized, including 9 grassland types at community level: F.Sibiricum steppe,S.baicalensis steppe,A.chinensis+forb s steppe,A.chinensis+bunchgrass steppe,A.chinensis+Ar.frigida steppe,S.grandis+A .chinensis steppe,S.grandis+bunchgrass steppe,S.krylavii steppe,Ar.frigida stepp e and 6 non-grassland types: cropland, urban area, wetland, desertified land, saline-alkaline land,and waterbody. To make the time series land cover classification data applicable for land use/cover change quantif ication analysis, the cloud, waterbody and cloud shadow features were e xtracted from each of the raw land cover maps and overlaid as a subset map. Then the area corresponding to the subset in each land cover classificatio n map was eliminated. After this procedure, each of the final land c over classification map of Xilin River Basin was optimized and ready for land use/ cover change detection.The main characteristics of land use/land cover change in Xilin River Basin over the past two decades were a significant decrease in area of meadow grassland, temperate grassland vs. significant increase in area of cropland, desert grassland, urban area and desertified land. From 1987 to 2000, the area of both F.sibi ricum meadow steppe and S.bacalensis meadow steppe decreased steadily year by year, whose net decrease was 525.5 km 2 and 201.5 km 2 . While the area of S.krylavii desert steppe and Ar.frigida desert steppe increased year by year, whose net increases were 1,282.7 km 2 and 1,045.6 km 2 respectively. The desert grassland had the greatest increase in a rea, i.e., 2,328 km 2 , equal to 56% of the total area of desert grassland in 1987. The cropl and and urban area increased from 114.3 km 2 and 25.2 km 2 in 1987 to 332.1 km 2 and 43.6 km 2 in 2000, respectively. The A.lymus+ bunchgrass steppe, A.lymus+ forbs steppe had the greatest decrease in area, i.e., 2,040 km 2 .During the four periods, A.chinensis+forbs steppe was the widest di stributed land cover type in 1987 and 1991, with its area was 5281.2 k m 2 and 4104.3 km 2 , respectively. However, in 1997 and 2000, S.krylavii was the most w idespread land cover type with an area of 4,109.6 km 2 and 4,479.1 km 2 .