Ecological Security Pattern Construction in Rural Settlements Based on Importance and Vulnerability of Ecosystem Services: A Case Study of the Southeast Region of Chongqing, China

With the development of urbanization, a large number of village settlements have disappeared. As important carriers of ethnic and cultural heritage, village settlements are important for the continuation of folk culture and farming spirit. Building a regional ecological security pattern helps to protect the integrity of village settlements and promote the sustainable development of the Chinese nation. In this work, the importance of ecosystem services was first obtained by using the Integrated Valuation of Ecosystem Services and Tradeoffs model (In-VEST) and the revised universal soil loss equation model (RUSLE) to evaluate the regional ecosystem services in the southeastern region of Chongqing (SRC). Then, the ecological importance evaluation results were combined with the sensory evaluation results to derive ecological conservation importance areas and identify ecological source points in their high-value areas. Finally, the ecological corridors were obtained by the minimum cumulative resistance model (MCR). The regional ecological security pattern was constructed, i.e., the triangular protection area strategy of "one screen, one belt, and three cores". The results show the following: the total area of ecological source sites larger than 20 km(2) in SRC is 436.02 km(2), accounting for 2.28% of the area of SRC. The largest ecological patch is 69.93 km(2), accounting for 16.04% of the total area of ecological source sites. Thirteen ecological source sites were identified as follows: four in Youyang County, three in Shizhu County, three in Wulong County, and one in Pengshui County. There are 78 ecological corridors with a total length of 4832.82 km, including 32 important ecological corridors with a length of about 1544.53 km and 46 potential ecological corridors with a length of about 3288.29 km. Based on the minimum cumulative model constructed by eight resistance factors, the spatial variation of the ecological resistance surface was analyzed, showing a trend of being high in the west and central part and low in the surrounding area. There are one high-value area of the resistance surface of Wulong County Nature Reserve and one high-value area of ecological sensitivity that overlap to the extreme, and which should be given sufficient protection attention. The core protected areas consist of three mountains including the Qiyao Mountain Range, the Wuling Mountain Range, and the Wulong County Nature Reserve. The ecological security pattern in SRC based on the mode of "source-ecological corridor-ecological node" can identify important ecological function areas, providing scientific guidance for sustainable development and ecological security protection in the ethnic village settlements in China.