Studies On Features And Reasons Of Degradation Of Urban Lake-Wetland In Wuhan

In this paper, we analysed features of biological, habitat and function of 23 lake-wetlands in Wuhan City based on field survey, and then we divided 23 lake-wetlands into 4 classes according to degradation degree. We also discussed degradation reasons, analysed the relationship between city construction and wetlands degeneration. The results are as follows:(1) 4 classes divided by degradation degree are:the first class is most slightly, such as zhuyehai Lake,yandonghu Lake,beitaizihu Lake and qingtanhu Lake; the second class is slightly, such as nantaizihu Lake,yezhihu Lake,sanjiahu Lake,tazihu Lake,huangjiahu Lake,yehu Lake,qinglinghu Lake and longyanghu Lake; the third class is highly, such as shahu Lake,nanhu Lake,zhangbihu Lake,yanxihu Lake,moshuihu Lake,beihu Lake,donghu lake and wujiahu lake; the fourth class is more highly, such as neishahu lake,and ziyanghu lake.(2) We also found urbanization was an important fact of degradation of wetland:the vegetation coverage rate outside the lake increases with increasing in the ratio of lake wetland's aline species; as the construction land coverage rate outside the lake increasing and the agricultural land coverage rate outside the lakes decreasing, the length of the longest line's succession and the average length of line's succession are decreasing; as the water coverage rate of outside the lakes increases with increasing in the species per hectare of the lake wetlands and the species per kilometer of the lake wetlands'perimeter.(3)Among lakes of different degradate degree, the most difference were the construction land coverage rate and the agricultural land coverage rate. As the construction land coverage rate increasing and the agricultural land coverage rate decreasing, the lake's degradation was more serious.(4)The results of principal component analysis showed that the reclaimed ratio, the decrease ratio of wetland area and the sewage quantity per hectare were main reasons of degradation of lake-wetland in Wuhan City.