Dynamic processes of two-way succession of natural and man-made wetlands in Sanjiang Plain

Based on remote sensing and GIS technology, the authors analyzed two-way succession processes of natural and man-made wetlands and impacts of natural environmental features on the processes in Sanjiang Plain during 1986-2005. Results showed that two-way succession processes of wetland in Sanjiang Plain were characterized with mutual transformation between marsh and paddy field from 1986 to 2005. During the periods of 1986-1995, 1995-2000 and 2000-2005, ratios of transformation area from marsh to paddy field to total area of transformed marsh were 7.61%, 37.99% and 28.81%, respectively, while ratios of transformation area from paddy field to marsh to total area of transformed paddy field were 4.83%, 13.69% and 4.84% respectively. Main natural environmental features in relation to two-way succession between marsh and paddy field in Sanjiang Plain were characterized by being the regions of meadow soil and marsh soil, elevation of 0-100 m, slope gradient of 0-1°, physiognomies of low flood plain, high flood plain, depression and first terrace.