A land-sea coupled framework for revealing hierarchical drivers of mangrove dynamics.

Clarifying the driving mechanisms of mangrove dynamics is essential for effective ecosystem management, sustaining key ecosystem services and supporting relevant Sustainable Development Goals. However, under the ongoing coupled influences of climate change and bidirectional human interventions, existing studies remain limited in integrating cross-system processes and disentangling complex relationships among multiple drivers. To address these challenges, we develop a Land-Sea Coupled Framework (LSCF) that explicitly links terrestrial and marine systems through riverine transport processes and represents key land-sea interaction processes using quantifiable variables. By integrating intelligent models and post-hoc interpretation techniques, the framework enables the identification of key drivers, as well as the characterization of their nonlinear effects and interactions. China's mangroves are used as a representative case to operationalize and demonstrate the framework. Results reveal a hierarchical structure in the driving mechanisms of mangrove dynamics. Specifically, land-use/cover change acts as the dominant driver, exhibiting increasingly nonlinear effects over time and significantly modulated by tidal range. Climatic drivers primarily function as indirect modulators, with stronger influences during contraction, whereas hydrogeomorphic features broadly shape ecosystem response patterns. Moreover, the co-occurrence of multiple climatic stressors may generate synergistic effects, thereby increasing the risk of mangrove contraction and highlighting the potential threat of compound climate extremes. Overall, the LSCF provides a transferable analytical framework for elucidating complex mechanisms of mangrove dynamics, and the resulting regional-scale insights can inform adaptive management and policy-making at local scales.