Mechanisms and scales in modeling forest responses to changing disturbance regimes.

Natural disturbances are major drivers of large-scale forest dynamics. However, the representation of forest disturbances remains oversimplified and poorly constrained in terrestrial biosphere models, compromising predictive performance under rapidly changing disturbance regimes. In this review, we first summarize the general mechanisms underlying vegetation responses to major disturbance agents across spatio-temporal scales, including occurrence regimes, immediate structural impacts, post-disturbance community reorganization, and long-term ecosystem feedbacks. Predictable patterns of the processes provide the ecological foundation of disturbance modeling. Subsequently, we synthesize progress and challenges toward more mechanistic disturbance modeling, organized by three generic modules: occurrence, impact, and post-disturbance dynamics. Future model developments should implement dynamic disturbance regimes, model lethal and nonlethal structural damage with trait-based hazard functions, and represent key ecological processes determining post-disturbance ecosystem dynamics - including different regeneration strategies, trait plasticity in response to rapid microenvironmental changes, and disturbance legacy effects. Finally, we discuss observational constraints on mechanistic disturbance models. Model parameterization and development can benefit from advancing disturbance detection and attribution via multi-modal and multi-platform remote sensing, ground measurements, and disturbance manipulation experiments. Altogether, mechanistic, scalable, and observation-constrained simulation of disturbance is essential for reducing uncertainties in forecasting global change impacts on ecosystems and carbon cycle feedbacks.