A non-equilibrium species distribution model reveals unprecedented depth of time lag responses to past environmental change trajectories

Previous studies have demonstrated legacy effects of current species distributions to past environmental conditions, but the temporal extent of such time lag dynamics remains unknown. Here, we have developed a non-equilibrium SDM approach quantifying the temporal extent that must be taken into account to capture 95 % of the effect that a given time series of past environmental conditions has on the current distribution of a species. We applied this approach to the distribution of 92 European forest birds in response to past trajectories of change in forest cover and climate. We found that non-equilibrium SDMs outperformed traditional SDMs for 95% of the species. Non-equilibrium SDMs suggest unprecedented long-lasting effects of past global changes (average time lag extent ranged from 9 years to 231 years). This framework can help to relax the equilibrium hypothesis of traditional SDMs and to improve future predictions of biodiversity redistribution in response to global changes.