塔里木河干流土地利用监测尺度分析

Scale Analysis for Land Use Monitoring in the Main Stream of the Tarim River

以塔里木河流域为研究靶区,选取20世纪50年代1:100000地形图52幅和2000年TM影像10景,解译得1:100000精度的土地利用数据,分别用1:2000000,1:1000000,1:500000,1:250000,1:100000,1:50000,1:25000,1:10000和1:5000比例尺的网格切割,运用面积频率统计和归一化尺度方差探讨20世纪50年代和2000年塔里木河干流土地利用总体和4个主要类别的最佳尺度,并分析各地类对尺度变化的敏感度。结果显示:塔里木河干流斑块面积相差悬殊,小到0.0001km2,大至19121km2;面积频率统计符合正态分布;归一化尺度方差显示50年代和2000年塔里木河干流适宜尺度都是1:50000比例尺,有林地、灌木林地、盐碱地的最佳尺度也在1:50000比例尺上,而沙地的适宜尺度在1:100000比例尺上;对尺度变化敏感度由高到低依次是灌木林地、有林地、盐碱地和沙地,2000年的敏感度高于50年代。

Selection of optimum scales is one of the key issues in the studies of ecology,geography, etc.Scale laws for land use monitoring need to be found out in different periods.The natural ecosystems are seriously degenerated in the Tarim River Basin,which was paid great attention.In this study,the scale change laws of general land use and four main land use types including woodlands,shrubbery lands,sandy lands and saline or alkaline lands in the main stream area of the Tarim River are lucubrated by interpreting the land use data in the 1950s and in 2000 using the available maps and RS images.By regarding the areas of land use types as the scales,the parameters are selected,the histograms of the areas of patches are charted,the normalized scale variances at 9 scales （1：2000000,1：1000000,1：500000,1：250000,1：100000,1：50000,1：25000, 1：10000 and 1：5000） are calculated,and the spatial distribution features and scale change laws of land use in the Tarim River Basin are lucubrated using normalized scale variances.Furthermore, sensitivity of land type with scale change is analyzed.The results are as follows：（1）The difference in areas of patches in the main stream area of the Tarim River is in great disparity,the patch of sandlands is the largest and its proportion in the year of 2000 was 43.77%. （2）The frequency distribution of the areas of patches,sandlands,saline or alkaline lands,woodlands and shrubbery lands in the main stream area of the Tarim River in the two study periods was in normal distribution,however,the positions of peak values and the distribution patterns were different,the positions of the peak values of sandlands and saline lands in the year of 2000 were in a range of 0.1-1km^2 and those of others were in a range of 1-10km^2.（3）The normalized scale variance figure reveals that most suitable scale of land use in general in the main stream area of the Tarim River is at 1：50000 or in a range of l：50000-1：100000.Expect for the optimal scale of sandlands at a scale of saline,woodlands and shrubbery lands is at a scale of 1：50000. The figures of normalized scale variances in the two study periods reveal that the change of the normalized scale variances of sandlands was tempestuous and was significantly higher than those of other land use types and; sensitivity of shrubbery lands was the highest,and then woodlands,saline and sandlands.Scale change rate was higher in 2000 than in the 1950s＇.It was found that sensitivity of saline,woodlands and shrubbery lands showed a marked increase in 2000.On the contrary,sensitivity of sandlands decreased in 2000.