Spatiotemporal Heterogeneity and Explanatory Factors of Ecosystem Functions and Services in Inner Mongolia

Arid and semi-arid ecosystems are being reshaped by climate variability and human interventions, but increases in individual ecosystem indicators do not necessarily translate into coherent gains in ecosystem multifunctionality. Inner Mongolia is a representative region for examining this issue because it spans a sharp transition from humid forested mountains to arid grassland, desert, and plateau systems and serves as an important ecological security barrier in northern China. Using multi-source remote sensing, meteorological, ecological observation, land-use, and socioeconomic data, we assessed changes in net primary productivity, soil conservation, water conservation, habitat quality, and a comprehensive ecological benefit index from 2001 to 2020. We found that ecosystem service capacity did not follow a uniform recovery trajectory. High values were persistently concentrated in the northeastern forested mountains, whereas western arid regions remained the main low-value areas. Temporal changes also differed among indicators: soil conservation increased most clearly, water conservation fluctuated strongly between years, NPP varied unevenly among ecological regions, and habitat quality changed only slightly at the regional scale. The integrated index further revealed a contrast that single indicators could not fully capture: the Loess Plateau–Loess Hilly Subregion and the Yinshan Mountains showed the strongest gains in comprehensive ecological benefits, whereas the Greater Khingan Mountains, despite having the highest baseline value, showed a decline. Spatial explanatory-factor analysis indicated that vegetation water consumption and precipitation showed high conditional spatial explanatory power for NPP, water conservation, habitat quality, and CEBI, whereas soil conservation was more strongly associated with nonlinear enhancement among factors; these q-statistics represent spatial associations rather than independent causal effects. These findings support region-specific management: maintain the stability of high-value northeastern forests, match restoration density to water availability in western drylands, and evaluate grazing and erosion-control measures using multiple services rather than vegetation greenness alone.