Revealing the spatiotemporal dynamics and nonlinear interaction-driven mechanisms of wetland ecosystem health in Northeast China using interpretable machine learning

• Integrated XGBoost-SHAP and PLS-SEM to uncover the complex driving mechanisms of WEH. • Found wetland ecosystem health in Northeast China to be generally moderate. • Identified total water resources and cropland area as primary drivers. • Observed strongest interaction between water resources and population growth with threshold effects. • Management levels indirectly reduce the positive effects of other factors on wetland health. Under the combined influence of global change and human activity, wetland ecosystem health (WEH) faces considerable challenges. Understanding spatiotemporal evolutionary patterns and the key driving mechanisms is critical for promoting scientific wetland conservation and sustainable development. However, prior studies have often overlooked the complex nonlinear relationships and interactions among multiple driving factors. In this study, we constructed a Wetland Ecosystem Health Composite Index (WEHI) by integrating the Driving Forces-Pressure-State-Impact-Response-Management (DPSIRM) and VORS models to assess the dynamic evolution of wetland health in Northeast China from 2000 to 2020. Extreme Gradient Boosting (XGBoost) combined with SHapley Additive exPlanations (SHAP) artificial intelligence techniques were used to analyze the nonlinear effects, interactions, and threshold effects of the driving factors. Partial least squares structural equation modeling (PLS-SEM) was applied to examine the direct and indirect pathways through which drivers influenced the WEHI. Swampland is the dominant wetland type in Northeast China, with frequent transitions among wetland types. The average WEHI is 0.4448, reflecting a moderate ecosystem health level, with poorer conditions in the south and better conditions in the northwest. Total water resources and cropland area are the primary drivers with significant nonlinear and threshold effects. The interaction between total water resources and natural population growth is most pronounced – when water resources fall below 15 billion m 3 , population growth significantly exacerbates wetland degradation. The management level acts as a mediating variable, indirectly weakening the positive effects of other drivers. Integrating XGBoost-SHAP and PLS-SEM provides an innovative and complementary analytical framework for exploring ecosystem health drivers, offering robust theoretical support for the scientific formulation of wetland protection and management policies and facilitating precise identification and application of multidimensional driver effects.