Study On The Construction And Optimization Of Urban Ecological Network

China’s rapid economic development has accelerated the speed of urbanization,and urban construction land has gradually occupied ecological land,leading to ecological problems such as landscape fragmentation and biodiversity decline.Constructing urban ecological network is an effective way to realize sustainable development in the broken ecological landscape.As the economic center in the south of the Yangtze River Delta,Ningbo City has been rapidly expanding in recent years,and the urban ecological environment has been threatened.Research on the construction and optimization of urban ecological network is conducive to improving the landscape connectivity of cities,thus maintaining the stability of urban ecosystems.Focusing on Ningbo city,this study utilized the MSPA method and landscape connectivity index to pinpoint ecological source sites.The evaluation system was constructed by combining landscape type,topography,and human activity factors to identify ecological corridors using MCR,thus constructing ecological networks for the study area in 2000,2010,and 2020.The ecological network was evaluated by using gravity model and network structure index.Based on the spatial and temporal trends of land use types,ecological source sites,ecological corridors and ecological nodes,the problems of the ecological network in Ningbo city during urbanization were analyzed.In light of current urban development,an ecological network optimization strategy is proposed,serving as a reference for enhancing urban ecological networks and promoting sustainable development planning.The obtained results have identified several notable points which are summarized as follows.(1)The land use types in the study area underwent a large-scale transformation from2000 to 2020,with an increase in the complexity of the patches and an increase in landscape fragmentation.During this 20-year period,construction land has rapidly encroached on cropland and forest land,and its area has increased by 223.04%;forest land has replaced cropland as the dominant land type,and the dominance of cropland has been continuously weakened;the change of land use area is:cropland>forest land>grassland>wetland>water>construction land.(2)During the three periods under study,the ecological source sites were primarily found in western,southern,southwestern and Hangzhou Bay regions of the study area,exhibiting an imbalanced distribution between the east and west.The area of ecological source sites in Ningbo decreased by 202.25 km~2from 2000 to 2020,but the rate of area decline gradually slowed down.In recent years,Ningbo has made progress in ecological environmental protection.However,despite these efforts,issues such as ecological fragmentation persist in the region.(3)High resistance areas are primarily concentrated in the central,northern,and southwestern parts of the study area,whereas low resistance areas exist mainly in the mountainous regions to the west and south,as well as along the coast.the area of high resistance areas increased from 3927.71 km~2to 4981.85 km~2from 2000 to 2020,and its area accounted for 53%of the total area of the study area.ecological corridors were simulated in 2000,2010,and 2020,respectively 91,91 and 78.(4)The number of primary ecological corridors decreased from 2000 to 2020 and were mainly distributed in the southern part of the study area.Interaction forces between ecological source sites weakened,which was not conducive to species migration and ecosystem stableility.the network structure index in 2020 was lower than that in 2000,indicating that the level of connectivity between corridors in the study area decreased.(5)Following the optimization of the ecological network in the study area,12 new ecological corridors and 4 ecological nodes were incorporated,alongside the identification of 67 ecological breakpoints and the addition of 11 new stepping stone patches.The values ofα,β,andγindices have been elevated to 0.45,1.84,and 0.64 respectively,leading to an enhancement in the connectivity and complexity of the ecological network in the study area.These improvements are beneficial for maintaining ecosystem stability and biodiversity conservation.