Maintaining or increasing water retention in ecosystems (WRE) can reduce floods and increase water resource provision. However, few studies have taken the effect of the spatial information of vegetation structure into consideration when assessing the effects of land use/land cover (LULC) change on WRE. In this study, we integrated the remotely sensed leaf area index (LAI) into the ecosystem process-based Biome-BGC model to analyse the impact of LULC change on the WRE of Beijing between 2000 and 2015. Our results show that the volume of WRE increased by approximately 8.58 million m³ in 2015 as compared with 2000. The volume of WRE in forests increased by approximately 26.74 million m³, while urbanization, cropland expansion and deforestation caused the volume of WRE to decline by 11.96 million m³, 5.86 million m³ and 3.20 million m³, respectively. The increased WRE contributed by unchanged forests (14.46 million m³) was much greater than that of new-planted forests (12.28 million m³), but the increase in WRE capacity per unit area in new-planted forests (124.69 ± 14.30 m³/ha) was almost tenfold greater than that of unchanged forests (15.60 ± 7.85 m³/ha). The greater increase in WRE capacity in increased forests than that of unchanged forests was mostly due to the fact that the higher LAI in unchanged forests induced more evapotranspiration to exhaust more water. Meanwhile, the inverted U-shape relationship that existed between the forest LAI and WRE implied that continued increased LAI in forests probably caused the WRE decline. This study demonstrates that integrating remotely sensed LAI with the Biome-BGC model is feasible for capturing the impact of LULC change with the spatial information of vegetation structure on WRE and reduces uncertainty.

Context Landscape planning to optimize ecosystem service (ES) provision requires an integrated understanding of different components of a provision chain (supply, demand, flow). However, the effects of landscape structure on ES flows remain poorly understood. Objectives The objective is to assess how ES flows quantitatively respond to landscape structure. Methods We proposed a framework that emphasizes ES flows from supply to demand and then applied it to China’s Three-River Headwaters (TRH). A structural equation model was developed to reveal the mechanisms linking landscape changes to ES flows under environmental constraints. Results We found an increasing trend for the water and soil retention services flowing out of the TRH during 2000 – 2020. The ES flows reached the maximum at a threshold with approximately equal areas for the supply and demand, but showed index-dependent variations with landscape structure. Specifically, ES flows increased with declined fragmentation and heterogeneity, and with enhanced connectivity of patches. The effects of precipitation and vegetation cover on ES flows were moderated by the variations in landscape structure. Conclusions Our study highlights the role played by the dynamics of supply and demand areas and their spatial arrangement in modulating ES flows. This framework could inform landscape planning to sustain ES provision and facilitate transboundary management.

Non-grain agricultural land use (NGALU) could be an alternative to payments for ecosystem services (PES) to achieve ecosystem benefits, given their joint contribution to forest transition. Unraveling the correlation between PES and NGALU can enhance cost-effective decisions. While farmland abandonment and non-grain cash crops (NGCCs) plantation are two main manifestations of NGALU, previous studies have primarily assessed the effects of PES on farmland abandonment. Little is known about the effects of PES on NGCC planting. This study evaluated the effects of China’s two nationwide PES programs (i.e., the Grain to Green Program, GTGP, and the Ecological Welfare Forest Program, EWFP) on NGALU in the Black River Basin of Shaanxi province. The study found a wide adoption of NGALU, with 52% of households adopting NGALU. The total area of NGALU is more than half of the afforested area through the GTGP. A quarter of the NGALU area is abandoned farmland, while the remaining NGALU area is planted with NGCCs. The two PES programs did not have effects on NGCC planting, but reduced farmland abandonment. Engagement in labor migration and local non-farm employment increased NGALU, while livestock breeding and farmland area reduced NGALU. Furthermore, the large area and unfavorable geographical conditions of farmland parcels promoted NGALU. These results highlight the important implications of leveraging NGALU to boost ecological gains from conservation investments.