Warming Powering Complex Pattern Of Alaskan Forest Damage - AP

[hatrack]

FAIRBANKS, Alaska -- Glenn Juday stands next to a white spruce that sprouted from seed two years after Britain ceased hostilities against the colonies in the Revolutionary War, the last time fire swept through the Bonanza Creek Experimental Forest. The 221-year-old trees are the monarchs of the northern boreal forest, rising 110 feet, and they have no business surviving on 11 inches of annual rainfall. "That's just ridiculously low," said Juday, a forest ecologist. What makes the forest possible are cool temperatures. At least they used to be.

A favorable combination of snow melt and rainfall that gives trees moisture just when they need it most has been disrupted by warming in recent decades -- more frost-free days, more 70-degree days, less heat loss at night, a potentially lethal combination to trees of the northern boreal forest. While climate warming has been most obvious in Alaska's glaciers and pack ice, it's also threatening to reshape the ecosystem that covers most of America's largest state.

Warming may be behind a proliferation of insects that have attacked trees in unprecedented numbers. It's a suspect in forest fires that burned a record 6.6 million acres in 2004. And drought brought on by warming threatens the hardwoods that stand next to the dominant species, the white and black spruce. Juday said that if warming continues to accelerate, insects, fire and drought will change Alaska's forest within decades.

EDIT

Juday, a professor of forestry science at the University of Alaska Fairbanks, grew up in Indiana but has studied Alaska's forests for 29 years, much of the time at Bonanza Creek, one of 26 sites established by the National Science Foundation for long-term ecological research. "It's much less of an intact forest than it used to be and it's got the decline processes under way that are going to do it in," Juday said. "A few of the trees will survive, and they'll become really old trees, but it's been hit pretty hard." He was skeptical of claims of global warming but observations in the forest proved difficult to attribute to other causes. He was swayed in part after disproving what every northern gardener knows to be true: That plants grow better if it's warm. For white spruce and some other trees in Interior Alaska, it's just the opposite. Tree ring studies indicated the most growth when temperatures are cool. Warm years stunt growth. "It was such a surprising result, we tested it in a lot of ways," Juday said.

EDIT

http://www.casperstartribune.net/articles/2006/09/11/news/regional/17bac97812d32299872571e500210e84.txt