Synergistic management of forest and reservoir infrastructure improves multistakeholders' benefits across the forest-water-energy-food nexus.

Forest management can influence multistakeholders' benefits across the forest-water-energy-food nexus at the watershed scale. However, bringing synergistic gains for multiple stakeholders is still a challenge for regional sustainable management. We took the Changhuajiang basin in China's Hainan Island as a case to present the impacts of synergistic management for upstream forest and reservoir optimization on the benefits of downstream hydropower enterprise and different farmers. By multimodel ensembles and scenario analysis, we quantified the relationships among upstream forest ecosystem management (rubber-intercropped), reservoir, water flow and downstream stakeholders' benefits (i.e., hydropower generation for the energy company, and available irrigation water for two downstream sites' farmers). We also adopted the genetic optimization algorithm to obtain the optimal reservoir infrastructure operation rule for the benefit improvement of multiple stakeholders. We found that rubber-intercropped management significantly increased reservoir inflow in the dry seasons (5%–170%) and reduced it in the rainy seasons (0.5%–7%). The irrigation water availability for downstream farmers in the Gao Canal and downstream irrigation areas correspondingly increased by 7% and 24.3% on average, respectively, with a slight change in hydropower production. Further, we found that water regulation by reservoir optimization operation could enhance the irrigation water supply (36.6–92% and 0–100% in Gao Canal and downstream irrigation areas, respectively) and hydropower generation (14.8–28.4%). This study indicates that the effect of upstream forest management on downstream multistakeholders' benefits could be strengthened by reservoir water flow regulation across the forest-water-energy-food nexus, and demonstrates the key role of infrastructure in regulating ecosystem service flow for strengthening the benefits of multistakeholders in the context of ecosystem management. [Display omitted] • Change in water flow improved irrigated areas' water availability and slightly changed hydropower generation. • Reservoir optimization further improved benefits for farmers and hydropower company by regulating water flow. • Synergistic management of ecosystems and infrastructure can improve multistakeholders' benefits. [ABSTRACT FROM AUTHOR]