The impact of China's grassland ecological compensation policy on herders' grassland use pressure and policy implications

Assessing the effectiveness of subsidies, supervision, and their combined instrument is critical for optimizing grassland eco-compensation policies. However, existing studies face methodological constraints in disentangling these three instruments due to contextual limitations. Leveraging the unique identity of grassland transfer-in herders, this study constructs a quasi-natural experiment using field survey data from 885 herders in Inner Mongolia Autonomous Region. We employ Propensity Score Matching (PSM) to isolate the independent and synergistic effects of subsidies and supervision on grassland use pressure. Attempts are made to rigorously disentangle causal relationships of policy effects within complex social-ecological systems. Key findings reveal that: Firstly, subsidy instrument reduces grassland use pressure by 2.5299 sheep units per hm2, equivalent to a 77.13% decrease in overgrazing severity. Secondly, supervision instrument decreases grassland use pressure by 1.8866 sheep units per hm2, reducing overgrazing degree by 60.28%. Thirdly, synergistic effects lower grassland use pressure by 2.1791 sheep units per hm2, diminishing overgrazing degree by 66.44%. These results demonstrate that economic incentives outperform supervision constraints, while synergistic effects exceed supervision instrument but remain weaker than subsidy instrument. Finally, the effects of subsidies, supervision and synergy on grassland use pressure reduction are more significant in small grassland scale herders, and the effect decreases in the order of synergy, subsidies and supervision. With different livelihood strategies, subsidies, supervision and synergy are all conducive to grassland use pressure, but synergy and supervision are more effective in non-grazing employment herders, while subsidies have little difference in grassland use pressure between the two groups. Future efforts should respect the phased law of policy implementation, enhance subsidy precision, improve supervision mechanisms and tools, and foster synergistic linkage between subsidies and supervision to achieve policy synergy.