Changes in tree species distributions are a potential impact of climate change on forest ecosystems. The examination of tree species shifts in forests of the eastern United States largely has been limited to simulation activities due to a lack of consistent, long-term forest inventory datasets. The goal of this study was to compare current geographic distributions of tree seedlings (trees with a diameter at breast height ≤2.5 cm) with biomass (trees with a diameter at breast height >2.5 cm) for sets of northern, southern, and general tree species in the eastern United States using a spatially balanced, region-wide forest inventory. Compared to mean latitude of tree biomass, mean latitude of seedlings was significantly farther north (>20 km) for the northern study species, while southern species had no shift, and general species demonstrated southern expansion. Density of seedlings relative to tree biomass of northern tree species was nearly 10 times higher in northern latitudes compared to southern latitudes.
Woodall, C.W.; Oswalt, C.M.; Westfall, J.A.; Perry, C.H.; Nelson, M.D.; Finley, A.O. 2009. An indicator of tree migration in forests of the eastern United States. Forest Ecology and Management. 257: 1434-1444.