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Alaska boreal forest ecosystem shifting: Study

US: A new study released in the scientific journal, Ecology Letters, offers one of the first confirmations of a wholesale shift in the boreal forest ecosystem due to climate change. Collaborators on the study, which compared three-ring data to satellite images, include Glenn Juday, a professor of forest ecology at the University of Alaska Fairbanks (UAF), and co-author of the article.

“This is one of the first extensive analyses of annual growth and climate response of black spruce in Alaska,” said Juday, who collaborated on the UAF research with Valerie Barber, Patricia Heiser and Emily Sousa.

Scientists at the Woods Hole Research Center and three other institutions based in Alaska and France conducted the study. UAF scientists were instrumental in the project, which involved one of the largest and most widely distributed samples of tree-ring data ever analyzed in Alaska: 839 trees, including 627 white spruce from 46 stands and 212 black spruce from 42 stands.

“Recent temperature increases have reduced tree growth over most of central Alaska, and increased growth in places where the temperature used to be too low for optimum growth, such as the Western Alaska tundra margin. Summer temperatures in central Interior Alaska are now almost too warm for white spruce to survive,” said Juday.

The study is the first time the two sets of data were compared, Juday said. “Every tree ring sample was compared to the satellite data and they mostly agreed. It’s particularly impressive that the tree ring and satellite data agree so well. This gives the final piece of assurance that this is real.”

Pieter Beck, a postdoctoral fellow at Woods Hole Research Center and lead author of the study, said the results offer evidence of the biome shifting in response to climate change and indicate that some ecosystem models may be missing changes happening in the circumpolar region.

“While the findings contrast with some recent model predictions of increased high latitude vegetation productivity, they are consistent with longer-term projections of global vegetation models,” Beck said.

Source: www.thearcticsounder.com