Abstract: With the aid of the 3S-technique and Fragstats software, the interp retation images (TM) of the plateau wetland reserve in 1990, 2000 and 2007 were analyzed for quantitative variation of the landscape thereof and its driving factors.Results show that degraded marsh is the background landscape of the reserve, accounting for 48.05% of the study area in 2007. During the first 10 years (1990 - 2000) after the establishment of the reserve, lakes, rivers and marshs therein decreased in area and evoled mainly to degraded marshes and meadows. The area of degraded marsh, meadows and shrubberies increased by 1 978.60, 2 559.09 and 824.27 hm2 , respectively; the number of patches and the heterogeneity and fragmentation degree of the landscape decreased; and the polymerization degree and dominance increased. After the establishment of the reserve (2000 - 2007) , the area of riverswas restored slightly. However, wetland degradation was still the main trend; the areas of lakes and marshes kept on decreasingwhile the area ofmeadow increasing; the area of denes increased by 1 929.00 hm2 ; the spatial heterogeneity and fragmentation degree of the landscape and the number of patches increased, while the polymerization degree and dominance decreased. Natural factors like globalwarming coup led with artificial ones, like drainage, over2grazing, disorderly tourism and construction of infrastructure were themain driving factors of wetland degradation.

Key words: plateau wetland, Ruo Ergai, landscape variation, driving force