Landscape ecological risk assessment and ecological security pattern construction in landscape resource-based city: A case study of Zhangjiajie City

Regional ecological security is an important part of the healthy development of modern cities. Scientific understanding and evaluation of regional ecological risks and construction of ecological security pattern are conducive to comprehensively improving the level of regional ecological security. Based on the remote sensing interpretation data onto Gaofen-2 of Zhangjiajie City in 2019, this paper used GIS spatial analysis and Fragstats software to construct landscape ecological risk index, and analyzed the spatial distribution characteristics of landscape ecological risk. And the minimum cumulative resistance model is used to construct resistance surface. At the same time, in order to intuitively reflect the magnitude of resistance encountered during species migration, this paper uses 9 natural protected areas as ecological sources, and selects six resistance factors including landscape ecological index, vegetation coverage, elevation, slope, distance from roads, and distance from waters calculate the resistance value. Combining the ecological source area and the minimum cumulative resistance value, Then we identified ecological corridors and ecological nodes, and finally built an ecological security pattern and proposed ecological security protection strategies. This paper takes Zhangjiajie city as an example to verify the function and effectiveness of the method. The results show that:（1） there are obviously spatial differences in landscape ecological risk in the study area, and the ecological risk presents a spatial distribution pattern of "the middle and surrounding areas are low, and the high value area generally extends along the Lishui River in a strip";（2） Low, relatively low, medium, relatively high, and high ecological risks area account for 21.59%, 41.79%, 22.57%, 12.08%, and 1.98%, respectively, among which the relatively low ecological risk area account for the highest proportion and the high ecological risk area account for the lowest proportion. The order of high ecological risk area pressure is: Yongding District>Cili County>Sangzhi County>Wulingyuan District;（3） The research identifies 24 ecological corridors and 47 ecological nodes. The cumulative length of ecological corridors is 872.35 km. And the spatial distribution characteristics of ecological corridors and ecological nodes are "three horizontal and four vertical" and "they are mainly distributed in the central and southern regions, and relatively few in the western and northern reg