TemporaI-SpatialFeatures of Land Use and Landscape Pattern in Lower Reaches of Heihe River

With the aid of remote sensing techniques,GIS,and landscape pattern analysis sottware FRAGSTATS,changes in land use and landscape pattern of the Ejina Basin,the lower reaches of the Heihe River were studied based on 1986 Landsat TM images and 2000 Landsat ETM Plus images.And driving factors of the changes were explored.Results showed that(1)the areas of grasslands,forestlands,water surface and cultivated lands were decreased in the 14 years,whereas the areas of alienated lands and deserted lands were remarkably increased.The dynamic changes in land use were characterized mainly by transformation of grasslands into deserted land,forestlands into grassland,and deserted lands back into grasslands.The change in spatial location of land use was greater than that in area.(2)Landscape fragmentation,diversity,heterogeneity and stability were obviously reduced.(3)Climatic warming-drying trend,reduction of the flow into the lower reaches of the Heihe River,and irrational human activities were the main driving forces accelerating this progress.