Climate change can have profound impacts on biodiversity and the sustainability of various ecosystems. Many studies have investigated the impacts of global temperature rise and suggested that species will migrate poleward and upward. The impacts of climate change on trees can be complicated, as different combinations of alterations in temperature and precipitation can result in different impacts and different tree species can have different responses to climate change. We lack a comprehensive understanding on large scale trait-specific impacts by climate change on forest ecosystems. Here, we analyzed the distributions of 86 tree species/groups across the eastern U.S. over the last three decades to (a) investigate the magnitude and directionality of their responses to climate change while accounting for successional processes and (b) provide a mechanistic understanding of the observed spatial shift.
Results/Conclusions
We show that more tree species have experienced a westward shift (73%) than a poleward shift (62%) in their abundance, a trend that is stronger for saplings than adult trees. The observed shifts are primarily due to the changes of subpopulation abundances in the leading edges, and are significantly associated with changes in moisture availability and successional processes. More importantly, these spatial shifts are associated with species that have similar traits (drought tolerance, wood density, and seed weight) and evolutionary histories (the majority of angiosperms shifted westward and the majority of gymnosperms shifted poleward). Our results indicate that changes in moisture availability have stronger near-term impacts on vegetation dynamics than changes in temperature.