Trees not adapting well to climate change

DURHAM, N.C., Oct. 31 (UPI) -- More than half of tree species in eastern U.S. forests aren't adapting to climate change as quickly or consistently as predicted, researchers said.

Nearly 59 percent of the species examined in a study by Duke University researchers showed signs that their geographic ranges are contracting from both the north and south, a Duke release said Monday.

"Many models have suggested that trees will migrate rapidly to higher latitudes and elevations in response to warming temperatures, but evidence for a consistent, climate-driven northward migration is essentially absent in this large analysis," James S. Clark, a professor of environment, said.

Fewer species -- only about 21 percent -- appeared to be shifting northward than predicted, the researchers said.

"Warm zones have shifted northward by up to 100 kilometers (62 miles) in some parts of the eastern United States, but our results do not inspire confidence that tree populations are tracking those changes," Clark said.

The concept of climate-driven migration assumes that as temperatures warm, the southern edge of some tree species' ranges would recede as adult trees die and seeds they leave can no longer sprout.

At the same time, the species could spread to higher latitudes as seedlings dispersed on their northern boundaries are able to take root in newly favorable climates.

The Duke study's findings show "a lack of evidence for climate-mediated migration, and should increase concern for the risks posed by climate change," Clark said.