Abstract:

For a transitional zone of arid and semi-arid ecosystems in northern China,the western region of Inner Mongolia plays a significant role in regional ecological security and sustainable development due to the spatiotemporal evolution and trade-off-synergy relationships of its ecosystem services.In response to the insufficient research on the 'long-term dynamic associations of multiple ecosystem services' in this arid-semiarid transition zone,this study conducted quantitative evaluations and relationship analyses.Using land use data for the years 1990,2000,2010,and 2020 in the western region of Inner Mongolia,and integrating the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) and Revised Wind Erosion Equation (RWEQ) models,we quantitatively analyzed the spatiotemporal differentiation of ecosystem services in western Inner Mongolia with carbon storage,soil retention,windbreak and sand fixation,and habitat quality,while Spearman correlation analysis was employed to reveal the trade-off and synergy relationships among ecosystem services.The results indicated that:1) In 1990—2020,the land use structure in western Inner Mongolia remained relatively stable,dominated by unused land and grassland,with significant conversions among cropland,grassland and water area.2) The spatial distribution of ecosystem services was primarily influenced by changes in ecological land use.Carbon storage initially declined and then increased,with a total decrease of 0.55%;soil retention first decreased and then increased,reaching a peak of 1.21×10⁹ t in 2020,with high-value areas concentrated in grasslands,croplands,and forest land;the areas with low windbreak and sand fixation expanded initially but sharply contracted by 2020,with high-value areas concentrated in the central-eastern region;habitat quality showed a decreasing-then-increasing trend,with low-value areas exceeding 60%,while high-value areas continued to shrink due to forest degradation.3) The trade-off and synergy relationships among ecosystem services were complex and dynamically changing,with overall synergy strengthening and trade-offs weakening.Carbon storage and soil retention exhibited stable synergies.There was a strong synergy between habitat quality and carbon storage.The synergistic trend of windbreak and sand fixation with soil conservation had emerged,and the relationship between carbon storage and habitat quality had shifted from weak trade-offs to no significant correlation.In the future,it is necessary to strengthen the regulation of conversions among unused land,cropland,and grassland with a focus on protecting forest land to prevent the reduction of high-value habitat areas,and to rely on the synergistic relationships among services to comprehensively enhance carbon storage,soil retention,and other functions.

Key words: Western Inner Mongolia, Ecosystem Services, InVEST model, RWEQ model, Trade-off, synergy