The Landscape Pattern and Ecologic Effect of the Marsh Changes in the Sanjiang Plain

Marsh was the most important and largest landscape in the Sanjiang Plain before the 19th century. With the repid increase of population and government investment, the farmland had been up to 524. 0 × 10 ha, the area of marsh had been down to 83. 5 × 104 ha in 2000, the landscape in the Sanjiang Plain had been in distinct changes. On the basis of remote sensing and GIS, using theory and methods of landscape ecology, the paper analyses quantificationally pacth areas, shape character and fragmentations of the marsh landscape in three periods of 1986,1996 and 2000, and surveys translation rates between marsh cover and other landcovers in the Sanjiang Plain from 1986 to 1996 and from 1996 to 2000, describes the spatial pattern of the marsh landscape in the Sanjiang Plain. The study indicates that the marsh area is being reduced increasingly, the marsh is being translated into cultivated land in larger range, and marsh landscape has been in the edge of complete fragmentation in the Sanjiang Plain. In the end, the paper analyses ecologic effect provoked by the marsh changes. In recent years, because of a large area of wetland being reclaimed in the Sanjiang Plain, ecological environment has been deteriorating , which also has resulted in the degeneration of land, the destruction of biodiversity , the decrease of valuable and rare animals and plants, and the descent of function of wetland.