[Construction of an Ecological Security Pattern in Karst Watersheds Based on Ecological Corridor Identification： A Case Study of the Nanming River Basin in Guizhou].

Constructing an ecological security pattern is important for maintaining the stability of the ecosystem in karst areas and promoting the sustainable development of regional social economy. This study takes the Nanming River Basin, a typical karst basin in Guizhou Plateau, as the research object, combines multi-source data, evaluates the ecosystem service （ES） of the basin by using the InVEST model, and identifies ecological source areas scientifically by combining ecological sensitivity, MSPA analysis, and landscape connectivity. The circuit theory is used to identify the ecological corridor and determine the points and obstacles, analyze the integrity and connectivity of the basin ecosystem, reveal the development trend of the basin ecological security, and finally form the ecological security pattern of the Nanming River Basin with the combination of "point-line-plane." The results show that： ① From 2000 to 2020, the ecosystem services of the Nanming River Basin showed a spatial feature of high in the northeast and low in the southwest. ② The ecological sensitivity of the Nanming River Basin was mainly low sensitivity, concentrated in the upper and middle reaches of the basin； the overall level of landscape connectivity was high, with uneven spatial distribution, showing a distribution pattern of high in the northeast and low in the southwest. ③ Patches with better habitat quality were selected as ecological sources, and 52, 52, and 65 ecological sources were identified in 20 years, with a total area of 460.36, 436.74, and 435.11 km, respectively, concentrated in the downstream of the basin with woodland and grassland as the land use types. ④ In this study, 116, 126, and 190 ecological corridors were extracted in 20 years, and short-distance corridors were mainly distributed in the northeast of the basin with a large number, whereas the southwest showed the opposite. A total of 419, 455, and 460 ecological nodes were identified in 20 years, among which the pinch points were mainly concentrated in the downstream of the basin with high vegetation coverage, which should be the key area for ecological protection. The obstacle points were concentrated in the upper and middle reaches of the basin with frequent human activities. The research results aim to provide theoretical and scientific basis for the improvement of ecosystem functions and ecological protection in the Nanming River Basin.