Phenotypic correlates of potential range size and range filling in European trees

Understanding the biological correlates of range sizes in plant species is important to predict the response of species to climate change. We used climate envelope models to estimate species’ potential range size and range filling for 48 European tree species. We hypothesized that potential range size relates to the climatic tolerances of plant species, and that the degree of range filling is influenced by species dispersal. We tested these hypotheses using, for each species, estimates for tolerance to cold and drought, type of dispersal, fruit size and seed size. Consistent with previous observations, we found that both the size of potential ranges and range filling increase from south to north. Species tolerance to temperature and water stress, as well as their dispersal-related traits also showed marked spatial patterns. There was, moreover, a significant positive partial correlation between cold tolerance and potential range size, when drought tolerance was partialed out, and a non-significant partial correlation between drought tolerance and potential range size, with cold tolerance partialed out. Range filling was not significantly larger in species dispersed by wind than in those dispersed by animals. There was a negative correlation between seed mass and range filling, but its statistical significance varied across different subsets of species and climate envelope algorithms; the correlation between fruit length and range filling was not significant. We conclude that climatic tolerances and dispersal traits influence species range size and range filling, and thus affect the range dynamics of species in response to global change. Using traits will therefore help to predict future distribution of species under climate change.