PARENT SESSION
Symposium 11: How Will the Southeast's Biological Diversity Respond to Climate Change?
Organized by: P White, J Walker, and J Sutter
Wednesday, August 6. 8:00 AM to 11:30 AM, SITCC Chatham Ballroom B.
Modeling potential suitable habitat and migration of trees in the eastern United States using forest inventory data and contrasting climate scenarios.
Iverson, Louis*,1, Prasad, Anantha1, Schwartz, Mark2, 1 USDA Forest Service, Delaware, OH, USA2 Department of Environmental Science and Policy, Davis, CA, USA
ABSTRACT- We automated species range maps compiled by Elbert Little in the early 1970s and summarized current forest inventory data, at a resolution of 20 x 20 km cells, for 135 species in the eastern United States to enable generation of tree biodiversity hot spot maps. The 135 species represent almost all tree species in the east that have a distribution range of at least 100 20 x 20 km cells, and do not include many endemic species from Florida. Highest diversities are present in the southern Appalachians and in the lower Ohio Valley. We next used a statistical model, DISTRIB, based on recursive partitioning, to estimate changes in potential suitable habitat for each of the species, assuming equilibrium of 2xCO2, under two climate change scenarios: the Canadian Climate Center model (CCC) and the Hadley Climate Center model (Had). These were the two scenarios used by the U.S. National Assessment for Climate Change. Summarizing these outputs allowed us to compile how the suitable habitat may change for this collection of tree species, and whether the biodiversity hot spots may eventually shift. As expected, the more severe climate change scenario, CCC, resulted in greater potential shifts in suitable habitat. Next, we ran a spatially explicit cellular automata model, SHIFT, to estimate colonization probability via migration, by 1 km cell, over the next 100 years, on five southern species (persimmon, sweetgum, sourwood, loblolly pine, and southern red oak). By evaluating the probability of colonization (via SHIFT) within the potential new suitable habitat (via DISTRIB), we can estimate the proportion of new suitable habitat that may be colonized within 100 years. This proportion is very low for all five species, suggesting that migration rates similar to that occurring through unfragmented forests during the Holocene will lag behind the rate of climate change.
Key words: migration, fragmented forests, climate change, tree distribution