Analysis of some key issues in selecting suitable scales in monitoring land use in the Tarim River Basin, Xinjiang, China

摘要

The selection of suitable scales is one of the key issues in the monitoring of the land use, or more generally, in the study areas of ecology and geography. The scale change trend of land use in the mainstream area of the Tarim River in recent 50 years are lucubrated in this paper by interpreting the land use data in the 1950s, 1970s, 1990s and 2000 with the available maps and RS images. Taking the area of land use as the parameter in selecting the scales, the histograms of the patches in area as are charted. The normalized scale variances under 9 scales are calculated. By reinforcing the calculated results with the landscape indexes including the Shannon-Weaver diversity index, Simpson diversity index and fractal dimensions, the characteristics and scale change trends of the land use in the Tarim River Basin can be summarized as following: (1) The variance of the areas as patches in the region is in great disparity. The patch of sandlands is the largest and its proportion in the year of 2000 was 43.77%; (2) In the course of the study period, the frequency distribution of the areas of patches, sandlands, saline or alkaline lands, forest land and shrub lands in this region was in normal distribution. However, the positions of the peak values and the distribution patterns were different; (3) Normalized scale variance table reveals that the most suitable scale of land use in the region is at 1:50000 or in the range of 1: 50000~1: 100000 in general. The general patterns of the normalized scale variances in the Tarim River Basin in the 4 study periods were similar; (4) Comparing with the normalized scale variances, there were no significant distribution trends of the three landscape indices.