Ecosystem service (ES) flows across geophysical and administrative boundaries are ubiquitous and are receiving more attention in an increasingly metacoupled world. Omitting trans-boundary ES flows from ES assessments will lead to unilateral conclusions and underestimation of ES contributions over distances. Inner Mongolia is an important ecological security barrier of China and Eurasia, but the trans-boundary effect of this barrier is difficult to be quantitatively evaluated and is rarely assessed. This study assessed the ecological security barrier function of Inner Mongolia from the perspective of trans-boundary ES flows, including wind prevention and sand fixation (WPSF), water provision (WP), carbon sequestration (CS) and livestock product provision (LPP) service flows. The trans-boundary value flows for the WPSF, WP, CS and LPP services in 2010 were 6.20 × 10¹⁰ CNY (Chinese currency, yuan), 0.21 × 10¹⁰ CNY, 1.29 × 10¹⁰ CNY and 1.27 × 10¹⁰ CNY, respectively, and 5.89 × 10¹⁰ CNY, 0.16 × 10¹⁰ CNY, 0.37 × 10¹⁰ CNY and 1.33 × 10¹⁰ CNY, respectively, in 2015; correspondingly, the percentages of these trans-boundary value flows in terms of the total value flow were 69.12%, 2.34%, 14.38% and 14.16%, respectively, in 2010 and 76.00%, 2.06%, 4.77% and 17.16%, respectively, in 2015. Therefore, WPSF service plays a more important role in the trans-boundary ecological security barrier function of Inner Mongolia. This study can enhance the understanding of trans-boundary telecoupling in an integral socio-ecological system and identify the critical ESs to form a foundation for ecological conservation measures considering sustainable development.

The shortage of water resources is a key factor limiting the sustainability of the economy and society. Most of the 25 National Key Ecological Function Areas (NKEFAs) in China serve as a source and supplementation for numerous rivers and playing an important role in water resource conservation. Based on the analysis of eco-environmental quality changes in NKEFAs, this study analyzed the spatial pattern of water conservation services in 2000 and 2010 by using a water balance equation. The results indicate that the land cover type of NKEFAs was dominated by grassland, and the proportion of ecological land conversion to non-ecological land (0.3%) was higher than that of non-ecological land conversion to ecological land (0.21%). The fractional vegetation coverage (FVC) and biomass density of NKEFAs gradually decreased from southeast to northwest. The FVC of the Changbai Mountain Forest Function Area (CBS) was the highest, while the biomass density and total biomass were highest in mountain areas in the Middle of Hai’nan Island (HND) and in the Great Khingan and Lesser Khingan Mountains (XAL) respectively. The FVC and biomass of NKEFAs mostly increased in 2000–2010. Water conservation amounts of NKEFAs decreased from southeast to northwest. The average water conservation and total water conservation amount of Nanling Mountain (NL), Guangxi-Guizhou-Yunnan (GQD), and the Wuling Mountain Function Area (WLS) were the highest, while the Yinshan Mountain (YS), Alkin Grassland (AEJ), and the Qilian Mountain Function Area (QLS) had the lowest values. In 2000–2010, the water conservation service of 60% of NKEFAs decreased. Spatial and temporal differences in water conservation services are the result of a combination of ecological environment quality and meteorological conditions. Protection of the ecological environment and vegetation coverage improvement should be strengthened to enhance the function of water conservation.

Research on the spatial flow of ecosystem services can help to identify the spatial relationships between service-providing areas (SPAs) and service-benefitting areas (SBAs). In this study, we used the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model to stimulate the flow paths of the wind erosion prevented by ecosystems in Hunshandake, China. By interpolating these paths, the SBAs were identified, and their benefits in terms of land cover, population, and Gross Domestic Product (GDP) were determined. The results indicated that the flow paths mostly extended to the eastern part of the study area, and the estimated cover of the SBAs was 39.21% of the total area of China. The grid cells through which many (≥10%) of the trajectories passed were mainly located in the western part of north-eastern China and the eastern part of northern China. The benefitting population accounted for 74.51% of the total population of China, and the GDP was 67.11% of the total in 2010. Based on this research, we described a quantitative relationship between the SPAs and the SBAs and identified the actual beneficiaries. This work may provide scientific knowledge that can be used by decision makers to develop management strategies, such as ecological compensation to mitigate damage from sandstorms in the study area.

Ecological restoration projects aim to recover ecosystems that have been degraded, damaged, or destroyed. The effective assessment of these projects is crucial for ensuring that restoration goals are met and for guiding future efforts. The Poplar Ecological Restoration Project (PERP), focused on removing floodplain poplar plantations, is a key environmental initiative in China to preserve the ecological functions and services of the Dongting Lake freshwater wetland complex. Understanding the dynamic changes in ecosystem services and their trade-offs/synergies before and after the project is crucial for ensuring that ecosystem services are maintained and enhanced. This study selected three key ecosystem services, water conservation, carbon storage, and habitat quality, as indicators to assess the PERP. Using the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model and geostatistical methods, including the Spearman correlation analysis and spatial autocorrelation analysis, we explored the ecological outcomes of the project. The results indicated that since its implementation in 2014, the PERP has significantly altered the land use and land cover (LULC) in the lake. Most of the former plantations have been converted into reedbeds (17,404 ha), followed by sedgelands (3841 ha), mudflats (443 ha), shallow waters (382 ha), and deep waters (301 ha). During this period, water conservation and habitat quality initially decreased and then increased, while carbon storage continuously declined. Overall, all assessed services showed an increasing trend except for carbon storage, resulting in a slight decrease in the integrated ecosystem services. Moreover, there were strong bivariate associations among the three investigated ecosystem services, and the synergies were strengthened during the project. Importantly, these synergies became positive after the PERP, meaning that the improvement of one service enhanced others, potentially leading to a more sustainable and resilient ecosystem.