Aspen trees in Fairbanks, part of the Alaska boreal forest in decline.

Photo by Ned Rozell.

In almost every patch of boreal forest in Interior Alaska that Glenn Juday has studied since the 1980s, at least one quarter (and as many as one-half) of the aspen, white spruce and birch trees are dead.

“These are mature forest stands that were established 120 to 200 years ago,” said Juday, a professor of forest ecology at the University of Alaska Fairbanks’ School of Natural Resources and Agricultural Sciences. “Big holes have appeared in the stands.”