Spatiotemporal variation characteristics of ecosystem health and its driving mechanism in the mountains of southwest China

A deeper understanding of the spatiotemporal variation characteristics of ecosystem health and its driving mechanism are important for ecosystem management and restoration. Under the complex environment in the southwestern mountainous area of China, various natural and anthropogenic factors interact with each other, complicating the mechanism driving ecosystem health. Quantitatively exploring the interaction among driving factors is challengeable but worthwhile. Based on the pressure–state–response (PSR) framework, the ecosystem health value of the study area was computed for the years of 2000 and 2018 at the grid scale. A geographical detector model was adopted to explore the factors driving ecosystem health change. We found that, compared to the year of 2000, there was an improvement in ecosystem health in 2018. The most significant improvement occurred in ample rural areas scattered in remote mountain areas. Nevertheless, there were grids experiencing ecosystem health deterioration. The appearance of a “deterioration ring” surrounding the metropolis region was the typical representative. Among the 10 selected driving factors, in-migrant population, out-migrant population, population density, elevation, and slope were found to be the most important factors. There were obvious impact thresholds of elevation, slope, distance to towns and distance to road on ecosystem health change. The out-migrant population in rural areas strongly promoted the local ecosystem health improvement by alleviating the pressure of human activity. In contrast, the in-migrant population presented the opposite effects on ecosystem health. All driving factors produced enhanced effects on the ecosystem health change through interaction effects. The largest enhanced effects occurred between the migrant population (in- and out-migrant) and the other eight driving factors. Our findings emphasize the key role of migrant population in ecosystem health change, which has not been considered in previous studies.