Send this article to Promobot

Alaska Science Forum: State forests in transition

December 28th 7:58 pm | Ned Rozell Print this article   Email this article   Create a Shortlink for this article



At his Dec. 7, 2012 presentation during the Fall Meeting of the American Geophysical Union held in San Francisco, Juday spoke of a "biome shift" now underway in Alaska — the boreal forest is suffering in the Interior and flourishing in western Alaska.



"The prospects are not good for survival (of white spruce, aspen and birch)," Juday said. "This . . . is not just an unlucky break at a stand or two, but is consistent with the first stages of a serious rearrangement of forest in the landscape across northern Alaska.

"The Interior forest is likely to retreat to cooler microsites, such as shaded slopes and somewhat higher elevations," Juday said. "Various kinds of stunted woodland, shrubland, and grassland are likely to expand where formerly our productive forest grew."


"This positive response extends out to the very western limit of tree establishment and survival at the edge of the tundra," Juday said. "The trees there are generally healthier than they have been at any previous point in their lives."

Juday said the current changes within Alaska's boreal forest will probably continue unless warmer air temperatures that started in the mid-1970s return to those levels or cooler.

"The future of the Alaska boreal forest is shifting decisively to western Alaska," he said.


Wiles used weather records from Sitka written down by the Russians as early as 1830 and later continued by Americans. He and his coworkers compared them to mountain hemlock growth (determined by studying tree rings) and have seen the trees' reactions to warmer air temperatures at different places on mountain slopes.

"Lower elevation (trees) are hurting, mid-elevation trees are tracking the change and high elevations are taking off," Wiles said. "All of a sudden, conditions are right for (the higher trees)."

Alaska rainforest mountain hemlocks seem to be experiencing the same "biome shift" Juday described in Alaska's boreal forest, Wiles said.

"These trees are adapted to the Little Ice Age," Wiles said, referring to a cold period on Earth from about 1550 to 1850. "Now we're out of the Little Ice Age."


"Is change happening faster than (these trees) can migrate?" he asked.


