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A perfect storm is heading for Northern Minnesota
The Forest of the Future: Ecologist Lee Frelich on the Fate of the Boundary Waters
by Kate Tyler
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 BWCAW, renowned forest ecologist Lee Frelich warns that the state’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 BWCAW 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 BWCAW 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 BWCAW 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 (Pinus banksiana), 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.
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.”
Trees not killed by blowdowns may be wiped out by pests, says Frelich, who has given over 100 media interviews and many public speeches on the future of the BWCAW. His interest in forest disturbance started early: he recalls being awestruck, as a small boy, as a towering elm fell during a thunderstorm near his childhood home in Janesville, Wisconsin. Now, equipped with high-tech measuring and tree coring instruments, he ventures regularly to forests in Minnesota and Michigan to study in detail how change affects old-growth forests (those that have progressed naturally for at least 120 years).
“Some of what I know I’ve learned directly from the trees,” says Frelich, whose BWCAW research sites include 500-year-old cedars. (Old-growth forests are rare in eastern North America, where only one percent of all forests escaped the lumberjack’s saw. The 1.1-million-acre BWCAW is of special interest to ecologists because fully half of it was never logged.)
“A tree is a witness to everything that happens in the forest—you just have to interview a tree a little differently than you’d interview a person,” Frelich adds. The rings of a cedar tree, for example, not only tell the tree’s age, but “also reveal how the tree responded to drought, whether it was burned by fire, and whether at some point the forest was opened up by a big thunderstorm or windstorm” (tree rings enlarge when sunlight and water increase).
If warmer temperatures and blowdowns already are transforming the BWCAW, 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.
Some invasive species that used to find Minnesota winters inhospitable may come to stay, including the Asian long-horned beetle (which kills both maples and aspens), as well as the emerald ash borer (already in Chicago). Even our next generation of trees is at risk. Hemlocks aren’t native in the BWCAW, notes Frelich, “but we would expect them to move in as our climate warms to supplant our jack pine, black spruce, and balsam fir.” The hemlocks may be accompanied by an insect known as the hemlock woolly adelgid, which has killed hemlocks from the middle of Massachusetts to the Smoky Mountains. “This does not bode well for our coniferous forest,” says Frelich.
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.
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.
“Fires keep the forest a healthy mosaic of different species of all different ages,” says Frelich. Fires once flamed often in the BWCAW, burning about one percent of the area each year until the early 20th century. That changed as roads and cities replaced the dry open land at the southern edge of the wilderness and as policies came to favor stamping out wildfires altogether.
“Without fire, we have aging forests that cannot renew themselves,” Frelich says. “Fire opens up the canopy and allows regeneration of species—white, red, and jack pines as well as paper birch and aspen. Many birds and animals prefer that habitat. Regular fires also will help trees adapt to a warmer climate—the seedlings that germinate are going to be the ones best adapted to current climate conditions.”
The Forest Service has for the most part shunned controlled burns as a “manipulation of the wilderness,” says Frelich. Yet exceptions have been made in the last few years for areas struck hard by the 1999 blowdown. “We need to recognize that our forests have been manipulated by human activity all along, from logging to global warming,” says Frelich. “Where the recent burns have occurred, the jack pine and the paper birch are coming back. We need to introduce controlled burns throughout the entire Boundary Waters area.”
Frelich knows that a more proactive forest management approach raises thorny questions about “what it is, exactly, we think the forest should be. No ecologist would propose that the forest be returned to a certain state and fixed for all time. We couldn’t go back to 1850 even if we wanted to; it’s already too warm,” he says.
It is, however, “fair to ask what species should be in a forest because conditions are suitable for it,” suggests Frelich. “If the climate is now suitable for hemlock in the BWCAW, and the only reason it isn’t there is because of landscape fragmentation or other problems created by human activity, then I think it’s appropriate to see that the hemlock is there.”
Ditto the tall white pines, he says. “They would still be in the BWCAW if the timber companies hadn’t cut them all down. Those trees live 400 years, and in my view it would be more respectful of the forest’s natural processes to spread seeds to restore the white pines than to say ‘we just need to leave the forest alone.’”
Details like these can and should be debated, says Frelich, but the bigger, bolder strategies needed to preserve the wilderness can’t be put off. “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 BWCAW from being wrecked. Then we can worry about exactly what we want it to be.”
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