Construction of urban landscape ecological security pattern based on circuit theory: A case study of Hengyang City, Hunan Province, China.

The identification of ecological sources and corridors plays an important role in the construction of ecological security pattern. However, previous studies mainly concentrated on the optimal path selection of species migration and diffusion rather than the random path selection of the species, which makes most conclusions fail to objectively reveal the process of species migration and diffusion. Taking the downtown area of Hengyang City as an example, we selected the ecological sources and ecological corridors with the habitat quality analysis module of InVEST and Circuitscape 4.0 and evaluated the importance and connectivity of relevant ecological elements with the Linkage Mapper, with the aim to construct the ecological security pattern and delimitate the regions prior to ecological restoration. The results showed that there were 85 ecological sources dominated by woodland and grassland, together with a small number of ponds and beaches, which mainly distributed in the southwest of Zhengxiang District, the west of Yanfeng District, the northeast and south central of Zhuhui District, with a total area of 11.8 km2. There were 60 ecological sources with centrality greater than 100, accounting for 70.6% of the total. There were 217 ecological corridors and five potential ecological corridors mainly composed of forest land, among which the proportion of shrubbery and sparse forest land was higher. The corridors with higher importance were mainly distributed in the west of the studied area. After removing the barriers, the regional connectivity had been significantly improved, with the highest extent of 54.9%. The priority areas of ecological restoration were classified into three levels according to the value of cumulative current, namely, the high-grade area, the middle-grade area and the low-grade area. The high-grade area covered 4.3 km2 of barriers, mainly distributed in the southwest of Zhengxiang District, northeast and south central of Zhuhui District. The middle-grade area was dominated by pinch area and ecological source area with centrality less than 100, covering an area of about 12.9 km2, mainly distributed in the central part of Zhengxiang District, northeast and south central of Zhuhui District. The low-level area was mainly distributed in south central of Zhuhui District, with 51.8 km2 of residual ecological sources. By coupling InVEST habitat quality analysis module and circuit theory, the ecological security pattern for biological protection was constructed, which provides scientific reference for biological protection.