Linking ecological degradation risk to identify ecological security patterns in a rapidly urbanizing landscape

Ecological security patterns (ESPs) aim to provide an effective spatial approach for maintaining urban ecological security based on the relationship between landscape patterns and ecological processes. However, the methods of selecting ecological security sources and evaluating resistance surfaces for ESPs construction are not well developed and lack consideration of land degradation and spatial heterogeneity. Using Shenzhen City, a fast-growing city in a rapidly urbanizing region, as a case study area, this study evaluated two types of land degradation risk for ecological land: type transformation risk and functional damage risk. Both two kinds of risk were combined with ecological functional importance, which was composed of habitat quality and landscape connectivity, so as to quantify the comprehensive reserve value of ecological land to identify the ecological security sources. Ecological corridors were established with the application of remotely-sensed impervious surface area in the ecological resistance surface evaluation. In all, 477.43 km(2) ecological land were identified as ecological security sources, with 278.1 km and 197.5 km for the length of group corridors and landscape corridors respectively. The ecological corridors spatially presented a radiation pattern of one axis and three strips. The majority of both ecological security sources and corridors was located within the existing ecological protection boundary, confirming its ecological significance. This study provided an effective quantification framework to identify urban ESPs, and ESPs mapping could make a fundamental support to urban planning.