Optimization Of Land Use Ecological Security Pattern In Yangtze River Delta Under Ecological Pressure

Under the background of rapid urbanization,ecological space is continuously squeezed by the urban space.Specifically,the natural habitat is divided into fragmented-mixed mosaic patches because of urban expansion.In addition,the rapid urbanization causes the degradation of ecosystem services,threatening regional ecological security.Given a good ecological security pattern is conducive to promoting the integrity of natural ecological structure and functions,and helping to balance between ecological supply and demand,constructing a land ecological security pattern is considered to be an effective way to ensure regional ecological security.The Yangtze River Delta is one of the most economically active and developed regions in China,and it is also an area that exists problems such as environmental pollution and ecological degradation.Furthermore,constructing an ecological security pattern in the Yangtze River Delta is a realistic requirement for implementing the sustainable development strategy of urban agglomerations.Taking the Yangtze River Delta of China as the study area,this study first identified ecological sources based on the Morphological Spatial Pattern Analysis(MSPA)and the landscape Connectivity Index.Then an ecological resistance surface that conforms to the environmental characteristics of the study area was constructed by considering both the physical and socio-economic factors.The hot spot regions with ecological pressure were identified by the energy ecological footprint model and the night-time light data.Both the corridors of ecological sources and that of demand for ecological pressure were constructed by the Minimum Cumulative Resistance(MCR)model and the gravity model.Finally,the optimal strategies for the land ecological security pattern are proposed,and the landscape pattern index is used to evaluate the optimized land ecological security pattern.The results showed that:1)From 2009 to 2018,the ecological pressure index of each city in the Yangtze River Delta region is greater than 1,and the ecological pressure presents obvious spatial difference:the ecological pressure faced by Shanghai and Jiangsu is overall greater than that of Zhejiang,and the maximum ecological pressure index gap value increases with time.The progress of the project shows a gradual upward trend.The overall ecological security situation in the Yangtze River Delta is not good,and it is urgent to implement ecological restoration and construction.2)The area of ecological source identified by MSPA was 25538.09 km~2,accounting for 24.18%of the total area of the study case,which was primarily distributed in the southwest of the study area.The hot spot regions with ecological pressure were mainly located in the east and north of the study area.There was no spatial overlap between ecological sources and hot spot regions with ecological pressure,thus there was a spatial decoupling to a certain extent between ecological supply and demand.Therefore,a new ecological source area of 1224.00 km~2was added to alleviate the contradiction between ecological supply and social demand in the northern part of the study area.3)The ecological resistance in the Yangtze River Delta region presents a spatial distribution characteristic of higher in the north and lower in the south.The low resistance area was mainly located in the west and south of Zhejiang and presented the distribution characteristics of concentrated and connected.High resistance areas were mainly located in the economic development areas of southern Jiangsu,Shanghai,and coastal Zhejiang,and their distribution characteristics were different:Southern Jiangsu and Shanghai showed the characteristics of patchy aggregation distribution.Zhejiang showed the characteristics of belt-like distribution along the coastline.In addition,there were also high resistance zones with small area and relatively fragmented distribution in central Jiangsu.4)The ecological corridor network consisted of an ecological source corridor and ecological pressure-demand corridor.The total length of the ecological source corridor was2784.99 km,presenting a spatial pattern of“two vertical and one horizontal”,and its suitable width was 1200 m.The total length of the ecological pressure-demand corridor was 1134.50 km,presenting a spatial cluster with ecological sources as the core.Meanwhile,the suitable width of the ecological pressure-demand corridor with moderate pressure,high pressure,and higher pressure was 650 m,280 m,and 100-200 m respectively.5)The ecological conservation zone,ecological control zone,ecological transition zone,production and living zone,and corridor restoration zone were identified,and their area respectively took up 48.02%、11.99%、23.06%、16.80%and 0.13%.The ecological conservation zone and corridor restoration zone are the key areas of construction land reduction,with the reduction area of 4205.20 km~2and 131.47 km~2 respectively.6)Compared with the landscape pattern index before and after optimization,CA index,PLAND index,LPI index,CONNECT index increased by 10.31%,10.35%,131.97%,and22.97%respectively,and SPLIT index decreased by 74.02%.The results showed that the fragmentation of the regional landscape was lower and the connectivity of the whole landscape was improved,which was conducive to ensuring the stability of the regional ecosystem and the continuation of the ecological process.