Abstract The ecological dynamic regime (EDR) framework was recently proposed as an alternative to equilibrium-based approaches for assessing ecological resilience in empirical systems, explicitly incorporating dynamic regimes as a reference for assessing the system's deviation during disturbances. Yet the lack of predictive capacity of the EDR framework limits its applications, especially when long-term data are unavailable or the disturbed system is not well represented by frequently observed dynamics. Here, we extend the EDR framework by introducing an algorithm (PETRA-EDR: Predicted Ecological TRAjectories in Ecological Dynamic Regimes) and a metric (MPD: Mean Predicted Deviation) to forecast ecological dynamics and estimate prediction accuracy. Our method employs multivariate analyses and can be applied to any ecological system characterized by a set of state variables (e.g. species abundances, functional traits). We conducted a simulation study to evaluate the performance of our method and illustrated its application using empirical data from Canadian boreal forests. Our results demonstrate the method's ability to forecast ecological dynamics and the effectiveness of distance-weighting functions in improving predictions while mitigating the effects of insufficient sampling, observation noise and hidden variables. Finally, we discuss the assumptions of our method and its applications for assessing ecological resilience to pulse disturbances and detecting regime shifts from a multidimensional, dynamic perspective.

Understanding the interplay between environmental conditions and physiological traits is essential to explain tree longevity in resource-limited environments. We studied old (up to 466 years) Thuja occidentalis trees growing on contrasting rock and gravel substrates to assess how substrate type and age influence hydraulic function, resource use, and survival strategies. Using dendroanatomical and physiological measurements, we compared key functional traits across 25 trees of varying ages and site conditions in Duparquet, Quebec, Canada. Our results show that trees on drier rock substrates exhibit smaller xylem tracheids, reduced theoretical hydraulic conductivity, and lower foliage density, enabling them to resist drought stress at the cost of limited growth. These conservative traits become more pronounced as the trees age and are associated with greater longevity, with the age of trees growing on rock substrates exceeding 300 years, whereas those on gravel substrates reaching up to 200 years. In contrast, trees on gravel demonstrate greater hydraulic efficiency and radial growth potential as a result of fewer resource constraints. These findings align with the hydraulic limitation hypothesis and provide valuable insights into how substrate conditions and age-related functional acclimation shape survival strategies in long-lived trees. Moreover, they highlight the importance of local site conditions in tree resilience and underscore the need for further research into the effects of environmental variability on tree physiology and morphology to better predict tree responses to future environmental changes.