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Lee Frelich

U forest ecologist Lee Frelich warns that Minnesota's premier north woods wilderness will lose its pines and moose within two generations.

The forest of the future

University ecologist Lee Frelich on the fate of the Boundary Waters

By Kate Tyler

Jan. 9, 2007

If you haven't yet had the thrill of seeing a moose amble up to a pine-shrouded lake in the northern boreal forest, you'd better plan a trip to Minnesota's Boundary Waters Canoe Area Wilderness soon. With climate and invasive pests both poised to wreak havoc on the Boundary Waters, renowned forest ecologist Lee Frelich warns that Minnesota's premier north woods wilderness--the most visited wilderness area in the country--is heading for a "perfect storm" of events so catastrophic that both pines and moose could vanish within two generations.

It's conceivable, Frelich says, that in just 50 years the Boundary waters could come to look a lot less like Canada and a lot more like, well, Nebraska.

"Unless we take steps now, the forests we have today simply won't be there anymore," says Frelich, a leading authority on forest disturbance who directs the University of Minnesota's Center for Hardwood Ecology. Logging, which clear-cut huge swaths of ancient white pines across northeastern Minnesota between 1890 and 1920, ended in the Boundary Waters in 1978, but tree-munching invaders and climate change can be just as devastating to the forest, he stresses, and much harder to contain.

"The idea that wilderness areas will take care of themselves if we just keep people out--ban logging, restrict motorized vehicles, keep mine tailings from draining into a watershed--that's an old model of wilderness management," says Frelich. "Global warming and exotic pests don't obey signs and boundaries. Unless we confront these new threats, they're going to change our unique and beautiful Boundary Waters forests beyond recognition."

Threats to the wilderness

Scientists see the seismic storm that blew down 400,000 acres of Boundary Waters forests in 1999 as one of many signs that climate change has begun to reshape northern Minnesota. The warming of the earth, largely the result of carbon dioxide and other emissions from factories and automobiles, clearly is driving severe storms father north, says Frelich.

Warmer summers and milder winters in the upper Midwest eventually will push out northerly species such as jack pine, red pine, balsam fir and black spruce in favor of southerly species such as red maple and oak (or the oak savannahs of the Great Plains if the warmer weather also brings drought, as some scientists predict). Even more profound--and less gradual--changes may be wrought by blowdowns, which upend the forest's natural processes of adaptation and change.

The 1999 blowdown "is pushing the forest forward to a state it wouldn't otherwise reach for 100 years," Frelich says. "People think that any disturbance returns the forest to a 'natural' state, but that's more true of fires than blowdowns." The slender jack pine, a hallmark of the boreal forest, depends on fire to reproduce, Frelich observes: its cones remain closed unless they're scorched by fire, and its seedlings grow only on a charcoal bed.

"The idea that wilderness areas will take care of themselves if we just keep people out... that's an old model of wilderness management," says Frelich.

It's not that jack pines are inherently preferable to the spruce and cedar that are sprouting up in their stead, says Frelich. "But the forest is an ecosystem, with many different plant and animal species that have evolved together. Blowdowns aren't a normal part of the natural history of the boreal forest the way fires are. They abruptly disrupt the gradual succession of species. And we do expect to see many more big blowdowns with global warming."

If warmer temperatures and blowdowns already are transforming the Boundary Waters, other changes are on deck. Milder winters will likely swell populations of deer, which may literally chew to extinction every last white pine, white cedar and yellow birch, says Frelich. Similarly, some insects (such as the mountain pine beetle), benign when in small numbers, are turning deadly as their numbers increase under more auspicious breeding conditions.

Minnesota's forests already are under siege by a more lowly invader: the worm. Frelich explains that all the earthworms and nightcrawlers in Minnesota are non-native species from Europe and Asia. They spread more quickly in a warmer climate, and are harmful because they eat the deep layer of duff (leaf litter) that insulates the forest floor. This intensifies the effects of climate change by making the soil drier. It also changes the seedbed, facilitating the growth of invasive plants such as buckthorn.

Jack pine trees line a lake.

A forest of jack pines at the Boundary Waters.

Photo by Lee Frelich

Until the last tree falls

"When you look at all this stuff--the deer and the worms already here, multiple invasive pests on the way, and the climate changes already happening--it's hard to imagine a more perfect storm heading for the Boundary Waters," says Frelich.

Still, he maintains, it's not too late to save the wilderness for the next generation. "I'm an optimist, and right up until the last tree falls, I'll believe it's possible to turn the tide," he says. "It may take a century or two with global warming, but if we take dramatic steps now-such as limiting CO2 emissions, developing hydrogen cars, pursuing renewable energy sources, and possibly also increasing the earth's reflectivity through white roofs and the like-we'll have a good chance."

Also needed, says Frelich, is a new paradigm of forest management "that recognizes that we can't just leave wilderness areas alone." Bold strategies are needed to curtail the movement of invasive species and to manage burgeoning deer populations, he suggests. Most of all, to ensure long-term biodiversity, the U.S. Forest Service "needs to restore fire to the forest in a meaningful way." Fires do release carbon dioxide, but their contribution to global warming is miniscule compared to the consumption of fossil fuels--and the resulting healthy forests store carbon.

The bigger, bolder strategies needed to preserve the wilderness can't be put off, says Frelich.

"We have to take immediate steps to curb global warming," he says. "Nor can we wait to curtail the spread of invasive species, manage the deer population, and restore fire. We have to keep the Boundary Waters from being wrecked. Then we can worry about exactly what we want it to be."

Edited from Imprint, a publication by the Bell Museum of Natural History.
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