Wetland evolution process of the three headwaters in the upper reaches of the Tarim River watershed based on RS

The characteristics of wetlands evolution process in three headwaters of the Tarim River watershed was studied based on 1975-MSS,2000-ETM and 2007-CBERS-2 remote sensing images.It showed that:①The characteristics of wetland evolution process were different between natural wetlands and artificial wetlands.During 1975 to 2007,the area of natural wetlands had reduced 1979.26km2 but artificial wetlands increased 188.53km2,the total area of wetlands in three headwaters of the Tarim River watershed decreased more than 1790.73km2 in recent 32 years,the speed of wetlands degradation was 55.96km2/ a.The area of swamp wetlands had reduced 1364.86km2 and it took 68.96% of the whole natural wetlands degradation.The rapidly degradation of swamp wetlands was the major factors which caused the wetlands deducing.②The patch number decreased from 388 to 305 during 1975-2000 and it was only 244 in 2007,the average patch area of wetlands landscape also reduced from 11.20km2 to 9.60km2 from 1975 to 2000 but it increased to 10.48km2 in 2007.The characteristic of wetlands evolution process was different between 1975-2000 and 2000-2007,it was shrinking hardly during 1975-2000 and the little patch of wetland died out in 2000-2007.③Shannon-weaner index and Fragmentation index were very low in the studied area and both of them decreased in the past 32 years,but the Dominance index continues decreased from 1975 to 2007,which reflected that the difference of the ratios of various landscape patterns increased and the dominant wetlands types had already changed from swamp wetlands in 1975 into river wetlands in 2000 and 2007.④During 1975-2000,the area that from wetlands converted to farmlands was 782.75km2 and it reduced to 606.48km2 from 2000-2007.It was the most significant in Hotan Region,the area that from wetlands converted to farmlands had reduced from 286.43km2 to 75.77km2,but it had no obvious effect in Kashgar Region,the area that from wetlands converted to farmlands were 361.22km2 and 361.51km2 in 1975-2000 and 2000-2007.The human activities strength in Kashgar Region was the most maximum in the three headwaters of the Tarim River watershed from 1975-2007.