As climate conditions change, tree species will have to “adapt, move, or die,” says Kevin Potter, a North Carolina State University scientist working with the USDA Forest Service Eastern Forest Environmental Threat Assessment Center. Trees can and do move their ranges over time in response to changing environments, but the process is relatively slow. A new climate may already be forcing shifts in some forest tree species, including their distribution across the landscape. Research by Potter and Eastern Threat Center ecologist Bill Hargrove aims to help forest managers remove some of the guesswork to ensure that trees planted for restoration, reforestation, or production are more likely to survive and thrive through environmental change.
Potter and Hargrove are developing methods to help forest managers decide where best to plant seeds based on the origin of the seed source as well as where to collect seeds that are to be planted in specific locations. To inform these decisions, the researchers have mapped 30,000 global “ecoregions,” areas with similar environmental characteristics, including temperature, precipitation, growing season, and soils.
By comparing maps of current ecoregions with future ecoregions determined by multiple climate projections for the years 2050 and 2100, Potter and Hargrove are able to visualize where on the landscape environmental conditions could be more similar or different as the climate changes. Using longleaf pine, flowering dogwood, and American chestnut as test cases, they have identified seed source origins and future suitable habitats for these native species important to the eastern United States.
Right: Longleaf pine seedling – Photo by Joseph O’Brien, USDA Forest Service, Bugwood.org
“It takes an immense amount of time and effort to perform field experiments in order to determine where trees from a particular location can thrive in current conditions, let alone under climate change,” Potter says. “Previously, researchers have done that work only for a small number of economically important species, so there’s very little information to help guide planting decisions for other species. Instead, we use the environmental conditions at a given species location to predict other places where that species could survive, both now and in the future. ”
“Seeds and seedlings may not be well adapted to their existing locations anymore as the climate changes,” Hargrove explains. “This is an approach that can help managers decide where else those local seeds should be planted, as well as where to go to get seeds that are more likely to grow into healthy trees at this location, in order to sustain forest resources for future generations of Americans.”
Learn more about this research: Potter, K.M. and W.W. Hargrove. 2012. Determining suitable locations for seed transfer under climate change: a global quantitative method. New Forests 43:581-599.