Landscape change and its eco-environmental effects in Ejin natural oasis
额济纳天然绿洲景观变化及其生态环境效应

The Ejin natural oasis landscape lies in the lower reaches of the Heihe river basin in the arid inland regions of northwestern China. With decreasing water resources from the upper reaches of the Heihe river basin, many serious ecological and environmental issues in the Ejin natural oasis have become more and more pressing in recent years. Using remote sensing techniques, GIS, and landscape pattern analysis software APACK, the landscape patterns changing characteristics, and the eco-environmental effects for Ejin natural oasis landscape are studied based on Landsat Thematic Mapper data in 1987 and Landsat Enhanced Thematic Mapper Plus data in 2001. The main results show that: 1) During the past 15 years, both the water area and main oasis area sharply decreased. The degree of oasis desertification process, at present, is more serious than before. 2) The most intense conversion among different landscape types was occurring in the transitional zone between oasis landscapes and desert landscapes. 3) As a result of the change of Ejin natural oasis landscape, the landscape patches shape complexity and its heterogeneity were obviously reduced. Moreover, the landscape texture became more and more coarser, the landscape diversity was decreasing and the landscape stability turned into unsteady. 4) Sharply decreasing surface water from the upper reaches of Heihe river basin is the vital factor for Ejin natural oasis landscape degradation in the past 15 years. The eco-environmental effects for Ejin natural oasis landscape induced by landscape change include the acceleration of groundwater mineralization degree, the degeneration of groundwater quality, the degradation of natural oasis vegetation, the decrease of species diversity, the increasing threats of sandstorms, the increasing quantity of ecological refugee and so on. In conclusion, the landscape condition of Ejin natural oasis landscape, today, is much worse than in the past years, with bad unsustainable developing trend.