Development and optimization of the ecological network in the Beijing-Tianjin-Hebei metropolitan region

Ecological security is the basic safeguard of human life.Rapid urbanization can cause fragmentation of large habitats and islands,and the deteriorating ecological environment is an increasingly serious problem.The establishment of an ecological network can not only enhance the connectivity between habitat patches and improve ecological function,but can also increase the comprehensive ability of the ecosystem and ameliorate the deterioration of the ecological environment.In this paper,the Beijing-Tianjin-Hebei metropolitan region was studied as the research zone.The ecological sources of the Beijing-Tianjin-Hebei metropolitan region were determined based on the Geographical Information System(GIS),and extracted via an overlap area of the forest,wetland,and grassland areas of the research zone,and the ecological red line;based on the least-cost-path method,we considered land use and elevation factors to extract the ecological corridors of the Beijing-Tianjin-Hebei metropolitan region to analyze and calculate the distribution of the ecological corridors.Integrating agravity model and connectivity among important ecological sources,the critical ecological corridors of the Beijing-TianjinHebei metropolitan region were selected,and then were overlaid with the current national roads and rivers to develop an ecological network and analyze the significant ecological nodes.The results indicated the ecological source area accounted for 21.76% of the total study area;the forest,wetland,and grassland was 82.78%,11.05%,and 6.17% of the total study area,respectively.Different geomorphology regions have different ecological source types;the forest was mainly distributed in mountainous regions,and wetland was mainly distributed in the plains regions,and grassland was mainly distributed in the northwest research area.As for the landscape impedance,the plains regions were higher than grasslands and forests,and the highest landscape impedance was found in the urban areas of Beijing,Tianjin,and Shijiazhuang.Among the 579 corridors selected according to the least-cost-path method,Zhangjiakou and Chengde areas showed better ecological networks,and the plains regions exhibited a serious loss in ecological sources and nodes.Finally,restoration and protection suggestions for the key ecological zones,such as Beijing,Tianjin,Baiyang Lake,and Hengshui Lake,have been provided in the study to offer reference for the development of the Beijing-Tianjin-Hebei metropolitan region.In additio