Identifying ecological security pattern and optimizing ecological resilience assessment for water-land coupling in Southwest China

Ecological security has dominated regional ecological stability in recent years. In order to clarify the ecological security pattern and ecological resilience in Southwest China and maintain regional ecological security, this study takes Southwest China as an example, uses InVEST, coupling degree model and other methods to quantify ecosystem services based on water-land ecosystem coupling, build an ecological security pattern and evaluate its Ecological resilience and propose optimization strategies. The results show that remarkable spatial heterogeneity was observed in the ecosystem services of the water-land coupling in Southwest China. There was the overall pattern of "higher in the west and lower in the east". The extremely high coupling level was distributed in the regions like western Sichuan, central Guizhou, and central Yunnan. While the low or non-existent coupling areas were around the large and medium cities. The pattern of ecological security also presented a "two cores and two belts" spatial configuration. One core was the contiguous areas of ecological sources in southwestern Sichuan and northwestern Yunnan. The secondary core of ecological sources was scattered in southern Yunnan. The "two belts" were the ecological corridors that centered around southern Chongqing and northern Guizhou, and the western edge of the Sichuan Basin, respectively. Specifically, 17 high-resilience ecological sources were concentrated around southwestern Sichuan and northwestern Yunnan. 34 high-resilience ecological corridors were distributed mainly along the southwestern edge of the Sichuan Basin and in southwestern Yunnan. The resilience of ecological pinch points was centered around central and western Yunnan and the southwestern edge of the Sichuan Basin. There was a concentrated distribution of the high and low resilience levels, where the highly resilient ecological pinch points accounted for 20.23%. An ecological resilience pattern was optimized as the "three axes, four regions, and five cores" along with the specific strategies. The targeted measures were also proposed for ecological restoration, such as soil and water conservation in the mountainous and hilly areas. Soil erosion was also prevented to consider the natural and human activities in the small watersheds. The water-land coupled ecosystem services were assessed to determine the impact of the interaction among different regional water-land ecosystem types on the ecological service supply and ecological security patterns. As such, the ecological security pattern was further optimized at a regional scale. The finding can also provide a scientific basis to precisely implement ecological restoration and regional ecological security.