Forest Service Study Confirms Effect of Climate Change on Trees in Eastern US

By Woodall, C.W.; Oswalt, C.M.; Westfall, J.A.; Perry, C.H.; Nelson, M.D.; Finley, A.O.
Washington, DC (May 1, 2009)- Scientists from the US Forest Service Northern and Southern Research Stations and Michigan State University have confirmed that geographic distribution of tree species is shifting north as a result of climate change. The results of this study, published in an article in Forest Ecology and Management, suggest that the process of northward tree migration in the eastern United States is currently underway for numerous species with rates approaching 100 km (62.1 miles) per century. The researchers also hypothesized that as northern and southern species move northward, other more generalized species may fill their niches in southern locations.

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 less than or equal to 2.5 cm) with biomass (trees with a diameter at breast height greater than 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 (greater than 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.
Related Resources:
An indicator of tree migration in forests of the eastern United States
Forest Ecology and Management- Volume 257, Issue5