Ecological dynamic regimes: A key concept for assessing ecological resilience

The increasing incidence of extreme events combined with long-term pressures due to climate change and anthropogenic activities are seriously threatening ecosystems worldwide. Promoting ecological resilience (i.e., the ability of ecosystems to absorb changes and maintain their processes and functioning) is a pivotal target for biological conservation. Many empirical approaches to assess resilience have relied on the underlying assumption that, in the absence of disturbances, ecosystems would be in a 'static' baseline state. In reality, ecological systems are highly dynamic and undergo phases of development and reorganization resulting from natural successional changes and their response to multiple interacting variables. As such, ecosystem states can be better described by 'dynamic regimes' rather than stationary states. In this context, there is an urgent need to expand the common 'equilibrium-based' approaches used in empirical ecology to evaluate resilience so that they can be applied to non-static ecosystems. Here, we present our perspective on the relevance of approaches based on dynamic regimes to assess ecological resilience empirically. More specifically, we briefly review the concept of resilience and discuss the main challenges for empirical applications. Then, we review an approach based on ecological dynamic regimes and temporal trajectories that can be used to assess the ecological resilience of non-static ecosystems from empirical data. Approaches focused on dynamic regimes help evaluate the management effort necessary to restore a disturbed ecosystem. Besides, they facilitate the identification of the factors that must receive special attention for enhancing ecosystem resilience.