Abstract:

Data of TM remote sensing in three time,652 sample plots, wetland distribution, vegetation distribution and topographic map was used to analysis change trend of of alpine wetlands in three rivers' source region near twenty years. The result was that: area of each land type has different degree change. Area of river,lake,low coverage grassland and marsh present decrease trend. Area of middle coverage grassland, high coverage grassland, river bottomland, nakerock and sandland present increase trend.Decrease scope of marsh is the bigges(16.73%), Increase scope of sandland is the biggest(123.58%).Wetland area of river, lake, marsh and river bottomland reduce 40 320.92 hm² from 1990 to 2007 year, it is 11.18% of total wetland area, each year reduced percentage is 0.66%,this show that all wetland will be disappeared after 150 year in this area if it don't protected.Range of area constitution of different land type hasn't change, show that proportion of each land type occupied space is relate steady. Type patches level show in pace with reducing of land type area, shape complex,fragmentation and dispersion of patches is decreasing. Landscope level show diversity, evenness and aggregation of patches is increasing,supperiority is decreasing.

Key words: three rivers' source region, alpine wetland, change trend, landscope