Studies On Ecological Sensitivity Of Urban Lake Wetlands In Wuhan

Ecological sensitivity evaluation can reflect the ecological environment condition of the urban lake wetland objectively and truly, and is the important theoretical basis to coordinate urban development with urban lake protection. Based on a survey of urban lake wetland in Wuhan,22 typical urban lake wetlands locating in the central city, suburb and outer suburb region in Wuhan city were chose. Based on the construction of the ecological sensitivity evaluation system of urban lake wetlands, the characteristic of the evaluation factors were analyzed. The ecological sensitivity of typical urban lake wetlands in Wuhan were evaluated comprehensively from the three aspects of landscape sensitivity, the wetland plants sensitivity and water ecological environment sensitivity. The protection and utilization strategies for urban lake wetlands of different categories in Wuhan were discussed. The main results are as followed:1. The landscape sensitivity of the urban lake wetlands locating in the central city, suburb and outer suburb have a none-significant difference. The area distribution region of urban lake wetlands in Wuhan is wide, and most of them are with the middle to small scale area; the water patch LSI of the urban lake wetlands which belong to the fourth grade and fifth grade account for 63.64%, and the water patch shape is regular.72.73% of the urban lake wetlands LSC belong to the third grade and fourth grade, which means the LSC are relatively low, and landscape effect is bad.2. The average numeric score of wetland plants sensitivity evaluation to the urban lake wetlands locating in the central city, suburb and outer suburb show a obvious decrease trend. It means that, the general plant diversity condition of the urban lake wetlands locating in the outer suburb is better than the suburb and central city. The wetland plants diversities of different lakes have a none-significant difference. The urban lake wetlands with a slight artificialized shoreline have a relatively high typical wetland plants ratio. The urban lake wetlands with a high human disturbance level have a high invasive plant ratio.3. The average numeric score of water ecological environment sensitivity evaluation to the urban lake wetlands locating in the central city, suburb and outer suburb are 1.37,1.1 and 0.44 respectively. This shows that, the water ecological environment of the urban lake wetlands locating in the suburb is a bit better than the central city, and the outer suburb is much better than the central city and suburb. For the TP, TN and NH3-N concentration, the urban lake wetlands locating in the central city are the highest, and the urban lake wetlands locating in the suburb show a notable difference, the urban lake wetlands located in the outer suburb are the lowest. The CODMn show none-significant difference within the urban region.4. The number ratio of different ecological sensitivity grades distribute more or less evenly. But the area ratio of the urban lake wetlands with low sensitivity grade and low-moderate sensitivity grade is 76.36%, and the area ratio of urban lake wetlands with moderate sensitivity is 14.57%. The area ratio of urban lake wetlands with moderate-high sensitivity and high sensitivity is 9.07%. Viewing from the urban region, the ecological sensitivity of the urban lake wetlands locating in the central city, suburb and outer suburb in Wuhan city show a notable decreasing trend, and the average numeric score of consolidated evaluation are 3.41,3.01 and 2.26 respectively.5. For the number ratio of different region, the ecological sensitivity of urban lake wetlands locating in the central city are the highest. The urban lake wetlands locating in central city with the moderate sensitivity grade to high sensitivity grade accounts for 85.72%, and none of the urban lake wetland locating in the central city is with the low sensitivity grade; Urban lake wetlands locating in suburb distribute more or less evenly at different grade; Urban lake wetlands locating in outer suburb are all with the low sensitivity grade and low-moderate sensitivity grade. Viewing from the the area ratio of different region, the urban lake wetlands locating in central city with the low-moderate sensitivity grade accounts for 66.88%, the moderate sensitivity grade accounts for 11.98%, the moderate-high sensitivity grade and high sensitivity grade accounts for 21.34%; the Urban lake wetland locating in suburb with the low-moderate sensitivity grade accounts for 79.49%, the moderate sensitivity grade accounts for 17.26%, the moderate-high sensitivity grade and high sensitivity grade accounts for 3.25%; the Urban lake wetland locating in outer suburb with the low sensitivity grade accounts for 86.88%, and the low-moderate sensitivity grade accounts for 13.12%, the moderate-high sensitivity grade and high sensitivity grade accounts for zero.6. The urban lakes in Wuhan city are divided into five categories according to the results of comprehensive ecological sensitivity evaluation, which are low sensitivity lakes, low-moderate sensitivity lakes, moderate sensitivity lakes, moderate-high sensitivity lakes, high sensitivity lakes. The properties of the low sensitivity urban lake wetlands are shown as low landscape sensitivity, low wetland plants sensitivity, and low water ecological environment sensitivity. The properties of the low-moderate sensitivity urban lake wetlands are as follows:most of the lakes show a high landscape sensitivity and the wetland plants sensitivity are moderate or low- moderate, the water ecological environment sensitivity are low or low-moderate. The moderate sensitivity urban lake wetlands have a significant difference in landscape sensitivity and the water ecological environment sensitivity, and the wetland plants sensitivity are moderate. The properties of the moderate-high sensitivity urban lake wetlands are shown as high landscape sensitivity, moderate wetland plants sensitivity, and high water ecological environment sensitivity. The properties of the high sensitivity urban lake wetlands are shown as high landscape sensitivity, low wetland plants diversity, and high water ecological environment sensitivity.7. The corresponding protection and utilization strategies to the low sensitivity urban lake wetlands are strictly prohibiting filling and eroding lake, protecting and developing by division, keeping a certain scale of fishing and agriculture production et al,. For the low-moderate sensitivity urban lake wetlands, the protection and utilization strategies are controlling development, ecological restoration, protecting habitat of animals and plants, constructing near-natural lakeside landscape, maintaining cultural and historical significance of urban lakes et al,. The protection and utilization strategies taken to the moderate sensitivity urban lake wetlands are giving priority to protection, controlling development, sewage interception and dredging, ecological restoration, strengthening connectivity between rivers and lakes, building lakeside green buffer zone, constructing urban wetland park et al,. The corresponding protection and utilization strategies to the high sensitivity and moderate-high sensitivity urban lake wetlands are strictly prohibiting filling lakes illegally, reasonable planning for the land use types around the urban lake wetlands, sewage interception and dredging, ecological restoration, strengthening connectivity between rivers and lakes, landscape reconstruction and promoting et al,.