Spatial Optimization of Forest in Small City of Metropolitan Area Based on Landscape Connectivity

Forest construction, which includes water systems and road ecological corridors, is one of the important aspects of the ecological environment integration construction of Nanjing, Zhenjiang and Yangzhou area. Taking Jurong City located in the center of Nanjing, Zhenjiang and Yangzhou metropolitan area as the object, this study analyzed the spatial distribution characteristics of the forest patches from 2017 to 2022 on the basis of landscape connectivity, with the integral index of connectivity (dIIC), number of components (NC), and betweenness centrality (BC) being indices. Furthermore, the exploration on the spatial distribution optimization of forest land was conducted building upon the internal forest patch connectivity and the distribution of forest land in Nanjing and Zhenjiang area. Results showed that the land use in Jurong City was dominated by agricultural land and construction land during the past five years, possessing the typical characteristics of small towns’ land use in the plain metropolitan area. The urban forest mainly clustered in two regions, including in the northern part where Baohua Mountain located and the southeast part where Mao Mountain situated. From 2017 to 2022, the area of forest land in Jurong reduced from 206.88 km² to 201.95 km², the optimal threshold distance for the landscape connectivity of urban forest in Jurong was 700 m. Under this threshold, the IIC of urban forest in Jurong decreased from 0.002 4 in 2017 to 0.001 7 in 2022. Spatially, the highest values of IIC and BC appeared in the northern Baohua Mountain area and the southeastern Maoshan area.However, with the urban development, the area of urban forest patches in Jurong had a greater impact on its dIIC. According to the boundary of the component in landscape connectivity and the source of potential land use, 2 889 potential spots for urban forest development were identified, with a total area of 29.05 km². In the light of the area and location of these potential patches, the potential land was divided into three types: such as short-term, medium-term and long-term level. The above findings can provide scientific reference for the construction and protection of forest land in small cities in metropolitan area.