Influencing factors and the establishment of a basin ecological compensation mechanism from the perspective of water conservation: A case study of the upper Yangtze River in China

Under the dual impacts of global environmental degradation and human activities, ecosystem service functions have steadily declined. Ecological compensation has emerged as an important direct and efficient motivator for countries to implement ecosystem protection and restoration. At present, few studies have considered ways in which to establish ecological compensation mechanisms or have analyze the related influencing factors. The ecological compensation threshold is in the conceptual analysis stage; thus, quantitative simulation studies are lacking. In this study, the relationship between water conservation and ecological compensation was analyzed. Scenario simulation and the minimum data method were combined to establish an ecological compensation mechanism for the upper Yangtze River (UYR) basin, and the ecological compensation thresholds were quantitatively assessed. Finally, the factors influencing ecological compensation and the interactions among the factors were analyzed using an optimal parameters-based geographical detector. The results showed that (1) the different land use scenarios for the UYR resulted in notable water conservation differences, with greater differences under the fallow-to-forest scenario than under the fallow-to-grass scenario and existing scenario. (2) Furthermore, 27 subbasins were suitable for the implementation of the fallow-to-forest scenario, with an average ecological compensation threshold of 46.48 yuan/m3 and an average new water conservation amount of 22.02 x 108 m3; and 21 subbasins were suitable for the implementation of the fallow-to-grass scenario, with an average ecological compensation threshold of 107.87 yuan/m3 and an average new water conservation amount of 3.72 x 108 m3. (3) The drivers with the highest and lowest impacts on the ecological compensation thresholds were the grain yield and NDVI, respectively, while their impacts on ecological compensation were significantly enhanced by interactions among the influencing factors. In this study, the differences in ecological compensation standards were compared at the basin scale and administrative scale in different regions worldwide. Moreover, the need to establish a basin-scale ecological compensation mechanism as an effective reference for promoting the implementation and development of ecological compensation policies was explored.