Colonization and extinction dynamics and their link to the distribution of European trees at the continental scale

Aim The population processes that drive tree species distribution are still widely debated. We test the hypotheses that metapopulation processes of colonization and extinction are linked to predictions of species distribution models. Location Europe: Spain, France, Germany, Finland and Sweden. Taxon Angiosperms and Gymnosperms. Methods For 17 tree species analysed, we fitted species distribution models (SDM) relating environmental variables to presence-absence data across Europe. Then, using independent data from national forest inventories across Europe, we tested whether colonization and extinction probabilities are related to SDM occurrence probabilities. Finally, we assessed the probability of presence at metapopulation equilibrium depending on colonization and extinction probabilities. Results We found that for most species at least one process (colonization/extinction) is related to SDM occurrence probability, but rarely both (only two species). Depending on the species, the link was either for colonization or for extinction, but relationships were generally weak. In addition, the metapopulation models tended to overestimate the occurrence probability at equilibrium. Main conclusions Our study shows that metapopulation processes are only weakly related to SDM occurrence probability and call for caution in extrapolating SDM models to metapopulation dynamics.