Study On Ecological Security Evaluation And Warning Of Xinghaihu Wetland

In the process of rapid urbanization,as an important part of urban ecological system,urban lake wetland not only faces the danger of a serious shortage of water resources to dry up,but also faces the crisis of the gradual loss of wetland ecological function caused by water pollution.The ecological security of the urban lake wetland is especially prominent in the arid region of northwest China where the water is scarce and the ecology is fragile.As a typical urban lake wetland in the northwest arid region,Xinghaihu Wetland has been affected by human activities in recent years,and ecological security has been seriously threatened.This study selected Xinghaihu Wetland’s monitoring data,survey data,remote sensing image data and statistic data of Shizuishan city in 2005,2008,2011,2014 and 2016.First of all,the individual evaluation of Xinghaihu Wetland was carried out from the aspects of economy-social impact,landscape safety,ecosystem health and ecological disaster risk;Then based on PSR conceptual model established comprehensive evaluation index system for wetland ecological security,through the quantity relationship weight method and analytic hierarchy process(AHP)to empowerment of indicators,using the weighted geometric mean method as basic algorithm of model,evaluated the ecological security status of Xinghaihu Wetland for various periods,and diagnosed problems with it,the positive and negative effects of human activities on urban lake wetland are demonstrated;Finally,the grey prediction model GM(1,1)is selected for the early warning analysis of the ecological security situation of the wetland in the future 10a,and the corresponding protection strategy is put forward.The preliminary conclusions are as follows:(1)The impact generated by social-economic development pressure on Xinghaihu Wetland ecosystem is lighter,but the increasing of urbanization,rapidly developed social and economy level and sharply increased urban sewage will be a potential threat to the wetland ecological security.(2)From 2005 to 2016,Xinghaihu Wetland’s landscape development intensity is between natural type and agriculture type,some land uses are irrational,and since 2008 LDI index presents rapid growth trend;The landscape pattern has changed significantly,the number of wetland patches has increased year by year,the fragmentation degree of partial landscape has increased year by year,and the stability of regional landscape has decreased.The overall landscape ecological risk index has a trend of wavelike rise.(3)The multi-year average ecosystem health composite index of Xinghaihu Wetland was 0.4960;the ecosystem health state from 2005 to 2016 respectively was sub-health,health,sub-health,sub-health and ill-health,ecosystem health composite index change significantly between different years.The deterioration of water environment quality caused by high nutrient salt content of nitrogen and phosphorus is the main factor threatening the health of wetland ecosystem in Xinghaihu.(4)The risk of ecological catastrophe of Xinghaihu Wetland is relatively low.In 2005,the ecological catastrophe risk of Xinghaihu Wetland was three-level.From 2008 to 2016,its ecological catastrophe risk was second-level.The catastrophe risk is reduced mainly because the improvement of the wetland management and protection.But since 2011,the increase of eutrophication index has increased the risk of wetland ecological disaster.(5)Between 2005 and 2016,Xinghaihu Wetland’s ecological security index fluctuated between 0.4837 and 0.5882.The ecological security level of each year is on an alert state,and the ecological security situation of Xinghaihu Wetland is not optimistic.Ecosystem health degree reduce,landscape ecology risk increase and ecological catastrophe risk growth was the important cause of the deterioration of the security situation of Xinghaihu Wetland,which is most serious with the ecological risk of landscape.(6)The wetland ecological security values of the future 10a of Xinghaihu Wetland are as follows:0.4812 in 2020,0.4567 in 2023,and 0.4335 in 2026.The future 10a’s states are all on alert;and even have a trend towards the development of medium warning.The threat of ecological security is becoming more and more serious.