Spatio-Temporal Evolution and Optimization of Ecospatial Networks in County Areas Based on Ecological Risk Assessment: Taking Dalian Pulandian District as an Example

The ecological security of a county is the basis for guaranteeing sustainable socio-economic development in the process of new urbanization, as well as the key to maintaining the rational functioning of natural ecosystems in urban and rural areas, and the primary prerequisite for satisfying the ecosystem service functions enjoyed by urban and rural residents. This study takes Pulandian, an estuary county with low mountains, hills, plains, and beach lands, as an example, and comprehensively applies various methods such as the model of driving–pressure–state–impact–response (DPSIR), the mainstream model of minimum cumulative resistance (MCR), the model of morphological spatial pattern analysis (MSPA), and the circuit theoretical model to assess the spatial and temporal evolution characteristics of the ecological spatial network of Pulandian District from 1990 to 2020 and evaluate its ecological risk from the socio-economic and environmental perspectives to provide a basis for the construction of ecological resistance surfaces. On this basis, an ecospatial network optimization model was constructed to reduce ecological risk and meet ecological security requirements. The results showed that the ecological space showed an upward trend of increasing, then decreasing, and then increasing in the area during the 30-year period, but there was serious fragmentation in the low area of the northeastern river valley, the low-hill plain area in the central part of the county, and the coastal area in the southeastern part of the county. High-resistance radiation centered on townships with high urbanization breaks the original ecological spatial network gradient, resulting in the absence of ecological corridors in large areas of the central and southeastern regions. Therefore, seven new ecological source sites were added for the central and southern portions of the study area, and the number of optimized ecological corridors increased from 47 to 66. In addition, we established an ecosystem consisting of an ecological barrier, an ecological coastal zone, multiple ecological corridors, and multiple ecological sites as an optimization system. This is of great scientific value and practical significance to provide reference for optimizing the ecological spatial network in Pulandian District of Dalian, to promote coastal ecological protection and construction, and to promote regional construction and sustainable development.