The Contrasting Effects of Local Environmental Conditions on Tree Growth between Populations at Different Latitudes

Abstract

Current widely used climate envelope approaches, i.e., correlations between climatic variables and the presence of a species, simulate responses for the whole species and predict future ranges based mainly on climatic suitability. However, short-term tree responses to climate change will take place within current populations, and these populations, acclimated to their local environments, are not likely to respond similarly to climate change. Thus, to develop reliable forecasts of forest responses to climate change, this variability among populations needs to be considered. In this study, we tested the effect of environmental conditions on the growth of two common maple species (Acer rubrum L. and A. saccharum Marshall) at two different latitudes within their northern distributional ranges. We collected increment cores, and analyzed year to year variabilities in tree growth as a function of temperature and precipitation. The results suggest divergent responses between species and between populations of the same species. Predicted growth under different climate scenarios for the region suggested that the growth of southern populations might decrease, while northern populations might still be able to retain their current growth. These results document the population-level responses to environmental conditions of these two species, providing latitude-specific guidance for future forest distribution prediction.