A Comparative Study On The Dynamics And Geologic Conditions Of Wetlands In Shangri-La County And Lijiang City In Northwestern Yunnan Plateau

The plateau wetlands found in northwestern Yunnan are unique ecosystems with important ecological and environmental values. They are also rather fragile due to the special physical geography conditions on the plateau. Based on Landsat MSS data in 1975, Landsat ETM+data in 2000, and Landsat TM data in 2008, geologic information of three major wetlands in northwestern Yunnan plateau as well as their temporal changes were investigated and their most influential factors were analyzed. The results indicate that the wetlands in northwestern Yunnan are not well developed due to the influence of mountainous landforms. Although the overall changes in the wetlands were not significant, there were significant spatial variations among the three regions because of different tectonic movements and human activities. The survey demonstrated that the marsh and lake wetlands in the northwestern Yunnan increased steadily from 1975 to 2000. This suggests that the improved awareness of environment protections has resulted in enhanced protection measures. Some marsh and lake wetlands were listed as Nature Reserves so that those wetland environments have been effectively protected and their area has been increased. The tectonic movement could also have contributed to the increase in lake and marsh wetlands. Wetland degradation and reduction between 2000 and 2008 were caused by regional climate changes, the expansion of farming lands around wetlands, and overgrazing on the mountain slopes.