Typical Alpine Wetland System Changes on the Qinghai-Tibet Plateau in Recent 40 Years
近40 年来青藏高原典型高寒湿地系统的动态变化

The wetlands in the source regions of the Yangtze and Yellow rivers and the Zoige wetland were selected as the typical wetland systems on the Qinghai-Tibet Plateau. This study evaluated changes in wetland components,spatial pattern and hydro-ecological function of the typical wetlands on the Qinghai-Tibet Plateau on the basis of three sets of remote sensing data (1969,1986 and 2000) and field investigations. In recent 40 years,the degradation of wetlands on the Qinghai-Tibet Plateau was prevailing with the declining area exceeding 10%. Among the three typical wetland systems,the most serious wetland degradation took place in the source region of the Yangtze River,and wetland area decreased by 29% and dried-up area of the lakes by 17.5%. The fragmentation and island of wetlands in the source region of the Yellow River and the Zoige region were accelerated. The degradation of the alpine wetlands resulted in the changes of their hydrological functions. In the source region of the Yangtze River and the Zoige region,where the wetlands declined more severely,the low water runoff decreased,the frequency of rare larger runoff increased and the frequency of regular runoff decreased. The water regulation capacity of all the wetlands was declined. The wetlands degradation was related with the air temperature rise. Under the air temperature rise by 2.3 folds of the average increasing magnitude during recent 40 years,the degradation of wetland systems was accelerated after the mid-1980s. Since the precipitation increased and glacier thawed,the wetland degradation was the main cause for river runoff decrease.