How landscape structure influences water-related ecosystem service flows

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. The objective is to assess how ES flows quantitatively respond to landscape structure. 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. 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. 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.