Dynamic Assessment Of Ecosystem Health In Leshan City Based On PSR Model

Ecosystem health refers to the stability and sustainability of an ecosystem,that is,the ecosystem has the ability to maintain its own functional structure stability,resist stress and pressure and self-regulate in time.Along with the rapid development of the global economy,human society is affecting the ecological environment with unprecedented intensity and scale.Global and regional environmental problems are gradually intensifying.In the meantime,human society has also paid attention to the sustainable development of the ecological environment.Therefore,the study of ecosystem health is becoming a hot topic in ecological research at home and abroad.Health assessment of ecosystems not only enriches the research content of ecology,but also has important practical significance in exploring regions and promoting the sustainable development of ecosystems.Leshan City is located in the southwest of Sichuan Province,which is an important tourist city in Sichuan Province,a central city in the south of Chengdu Economic Zone,and an important port city and transportation node of Chengdu-Chongqing Urban Agglomeration.Leshan City is located in the transitional zone from Sichuan Basin to Southwest Mountain.The climate and topography are complex and changeable.The special geographical location and complex topographic conditions create rich natural resources.It is of great research value and significance to choose Leshan City as the research object of ecosystem health.Firstly,the present situation and dynamic change process of Leshan ecosystem are analyzed.Taking county-level administrative districts as research units,based on the"Pressure-State-Response"evaluation model,14 indexes from 3 index levels of pressure,state and response are selected to construct Leshan ecosystem health evaluation index system.Entropy weight method based on time series is used to calculate index weight.Combined with GIS and RS technology,the spatio-temporal change process of ecosystem health in Leshan City in 2009,2013 and 2017 was analyzed.The main contents and results are as follows:(1)The land use structure of Leshan ecosystem is mainly forest land,accounting for 64.83%of the total area of the region,followed by cultivated land,accounting for25.44%of the total area of the region.Grassland,construction land,water area and unused land account for 1.79%,2.79%,5.04%and 0.12%of the total area of the region,respectively.(2)From 2009 to 2017,the transfer area of non-construction land to construction land in Leshan ecosystem totaled 53.62 km~2,accounting for 74.86%of the total regional land transfer.The degree of change within the ecosystem in 2009-2014 is more intense than that in 2013-2017.(3)In the ecosystem health assessment system,the state index layer has the largest weight,which is 0.3976,followed by the response index layer(0.3719),and finally the pressure index layer(0.2305).(4)On the spatial scale,the ecosystem health of all districts and counties in Leshan City decreases from southwest to northeast.The ecosystem health of Jinkouhe District,Ebian County and Mabian County is higher in the region,while the ecosystem health of Jingyan County,Jiajiang County and Wutongqiao District is lower in the region.(5)On the time scale,the ecosystem health of Leshan City has improved annually.The ecosystem health of all districts and counties has improved to different degrees from 2009 to 2017,with Shawan District having the most significant improvement.