[Landscape change in middle Heihe River Basin].

Using GIS and a landscape structure analysis program FRAGSTATS, this paper dealt with the landscape change in the middle Heihe River Basin during the past 20 years. During the past 20 years, the landscape elements had a complex change of landscape structure and an apparent transition of landscape composition, but the landscape in a whole still displayed a pattern of sharply contrast between oasis landscape and desertification landscape. Human activities significantly changed the distribution and allocation of the limited water resource in the basin, leading to an acute contradiction between desertification and oasisfication. Moreover, the transitional area between desertification and oasisfication was very sensitive to these processes. The decrease of Shannon's diversity index and evenness index manifested the intensive management and reconstruction of landscape by human beings, which improved the socioeconomic benefits of the region on one hand, but decreased the landscape heterogeneity and landscape diversity, leading to the decrease of eco-environmental benefits of some areas in the basin on the other hand. The research method and technology used in this paper were also discussed.