Study Of Ecological Network Construction In The Chang-Zhu-Tan Core Area Based On Ecological Spatial Landscape Evolution

With the accelerated urbanization in China,the contradiction between economic development and ecological protection has become increasingly prominent in urban agglomerations where economic activities are highly concentrated,which has caused a series of eco-environmental problems.The ecological space of urban agglomerations is an essential guarantee for regional sustainable development.The ecological space of urban agglomerations is an essential guarantee for regional sustainable development.In recent years,studying the ecological spatial pattern and network structure of urban agglomerations has gradually become a hot spot in constructing ecological civilization.This paper takes the research object of the Changsha-Zhuzhou-Xiangtan core area,which has the most significant growth and construction intensity.Based on the Google Earth Engine cloud platform,the ecological spatial information of the study area was extracted based on Landsat images of 5 periods from 2000 to 2020.The GIS spatial analysis,landscape pattern index,and remote sensing ecological index model were used to analyze the evolution characteristics of the ecological landscape and the dynamic change pattern of ecological environment quality.On this basis,morphological spatial pattern analysis,landscape connectivity analysis,Linkage Mapper,and ecological network structure analysis were applied to construct,optimize and evaluate the ecological network.The main conclusions are as follows:(1)From 2000 to 2020,the forest was the primary ecological space landscape in the study area,followed by water,and grassland accounted for the smallest area.The ecological space had been decreasing continuously,with a total reduction of 976.96 km2.From the change of single landscape dynamic degree,it can be seen that the forest area had shrunk most significantly,followed by the grassland area,while the water area had increased.From the changes in the comprehensive landscape dynamic degree,it can be seen that the rate of reduction of the ecological space area was the largest from 2005 to 2011,with a comprehensive landscape dynamic degree of 2.23%,mainly due to the conversion of large areas of forest to cropland and construction land.(2)During the past 20 years,the landscape pattern of the study area had changed dramatically.At the landscape level,the fragmentation of the overall ecological space had increased,the landscape patches tended to be discrete,and the heterogeneity of the study area’s landscape had increased due to the influence of human activities.At the type level,forest,grassland,and water fragmentation continued to intensify from 2000 to 2011.After 2011,the fragmentation of each landscape in the study area improved with the promotion of ecological civilization.(3)The overall eco-environmental quality of the study area was on a downward trend.Regarding spatial distribution,the eco-environmental quality showed evident spatial heterogeneity,with an overall distribution pattern of suburban counties outperforming central urban areas.Over the past 20 years,the area with significantly deteriorating eco-environmental quality was mainly located in the central urban areas of Tianxin District,Yuhua District,Furong District,Yutang District,Hetang District,and Tianyuan District.The area with improved eco-environmental quality was mainly located in the study area’s western and southern mountainous,hilly regions.(4)By constructing the ecological network,it was found that the core ecological source sites were mainly located in the northeastern and southern regions,resulting in an uneven distribution of ecological corridors and poor connectivity between the east and west of the study area.Based on this,new stepping-stone patches and ecological corridors were added to improve the integrity of the ecological network.The evaluation of the ecological network before and after optimization showed that the ecological network closure(α index),node connectivity rate(β index)and ecological network connectivity index(γ index)all improved in the optimized ecological network,indicating that the optimized ecological network was reasonable.The findings of this paper can provide a theoretical basis for planning ecological civilization construction in the Chang-Zhu-Tan region,which is essential for promoting the high-quality integrated development of Chang-Zhu-Tan and providing a reference for the construction of ecological networks in rapidly urbanizing areas.