An Ecosystem in Transition: The Boundary Waters in a Warming World

Art & Science

Melting ice caps, record floods, freak storms, rising sea levels threatening to swallow entire island nations — hardly a month goes by without a story of a disaster linked to a warming climate. Some of us have seen the impacts firsthand, whether in the nearly depleted reservoirs of the Colorado River, or the mega heatwaves that have hit once temperate areas like Portland, Oregon.

If you were to take an autumn drive along Highway 61 or through the forest roads around the outskirts of the Boundary Waters, it would be impossible not to notice the clusters of red and orange leaves flaring out from the maples and oak saplings. These southern species trees have been steadily creeping north. Stunning though such foliage may be, they are signs of a profound shift in the ecosystem, a shift that might, in our lifetime, fundamentally transform the northland.

Fall colored trees in reds, yellow and greens, near some clean water in the BWCA

For many, the Boundary Waters is a place that stands apart from the noise of the modern world. It’s a place that is much the same as it has been for centuries. This could all dramatically change. There is an urgent need to understand how climate change could impact the BWCA so we can prepare, adapt, and preserve the magic and wonder that has moved so many for so long. In this article, we’ll focus on these possible changes, and what the future might look like.

The Boundary Waters is at the southern edge of the boreal forest, an enormous ecosystem encircling the northern hemisphere and spread across the Eurasian and North American continents. Comprised of spruce, firs, aspen and birch, the boreal forest extends to the northernmost limit of the tree line. North of this, it is too cold for trees to grow. Trees in the boreal ecosystem have adapted to thrive through long, cold winters — conditions in which southern species, such as oak and maple, simply cannot survive.

Dr. Lee Frelich, the Director of the University of Minnesota Center for Forest Ecology, describes these trees as having antifreeze in their sap. However, this natural barrier created by the cold is breaking down. Warming conditions have made it easier or oaks and willows to creep north, take root, and compete with species such as black and white spruce, paper birch and other trees native to the boreal biome. Further, Dr. Frelich says that changing conditions could result in a climate that is too warm to support a boreal forest, leading to the widespread die-off of the boreal forest from northern Minnesota to as far north as Edmonton, Alberta.

The result of this would mean that the boreal forest would effectively leave Minnesota, and an oak savannah would take its place.

Dr. Frelich notes that events triggered by climate change could quicken this transition. For instance, drought and forest fires brought on by climate change would clear large areas of forest, making it easier for oaks and grasslands to seed and grow. The same could happen in the case of a massive die off of boreal tree species.

Forest succession is currently taking place. According to Dr. Frelich, if we continue with “business as usual,” that is, keep emitting CO2 at the current rate, by about 2070, the climate in the western Boundary Waters would no longer support forest of any kind, and will have been replaced by oak savannah, while oak and maple forests might still be supported in the eastern BWCAW.

How soon depends on us. If we reduce CO2 emissions and meet the goals of the Paris Agreement and Glasgow Summit, maple and oak will continue to move in and mix with boreal trees. The Boundary Waters will change, but not in such a dramatic, fundamental way.

In 2006, the moose population in Minnesota began to dramatically decline. In the following decade, moose numbers dropped by half. This alarming die off was accompanied by speculation and uncertainty. Some wanted to blame wolves, but wolves prey on calves and young moose, which did not account for why so many adult moose had died.

Dr. Seth Moore, the Director of Wildlife and Biology with the Grand Portage Band of Lake Superior Chippewa, began to investigate. One of the more noticeable changes in the area was that whitetail deer had become more common, migrating north as the forests that were once too cold to support a viable whitetail population, warmed.

It’s not that the deer competed with moose. Rather, what Dr. Moore and his colleagues found was that the deer carried a parasitic brain worm that they transmitted to the moose. As regular carriers of the brain worm, whitetails have evolved natural protections against the parasite, rendering it harmless. In moose, however, the brain worm can be deadly.

Once the eggs hatched, the worms tunneled into the moose’s brain, inflicting serious damage that often resulted in a premature death. Brain worms weren’t the only parasites harming moose. Warming conditions have led to an explosion of ticks in the northern portion of Minnesota. Ticks would cover moose by the thousands. To relieve themselves, the moose would scratch themselves against trees, scouring off large chucks of the fur they needed to stay warm. The resulting hypothermia and blood loss from tick infestation were another factor that likely contributed to a rise in moose deaths.

Though the moose population in northeastern Minnesota has not recovered, it has stabilized, and is even showing some signs of increasing. Efforts are underway to ensure moose can once more thrive in the region. Most recently this was seen at the end of 2022, when the National Fish and Wildlife Federation awarded a federally funded grant of almost half a million dollars to fund a new collaborative between state, federal, and tribal agencies, as well as organizations and private landowners, that will restore moose habitat in at least three large tracts of land — ranging anywhere from 10,000 to 50,000 acres.

Such initiatives, along with a succession of colder, snowier winters that seem to have helped with the ticks and the whitetail deer populations, have been signs of hope for this iconic Northwoods species.

Almost everyone who has canoed through the Boundary Waters has dealt with mosquitoes, and if you’ve been there in early summer, you’ve probably had to face the black flies. Like ticks, the

population of these small, biting insects is on the rise. And this means more than spoiling plans to spend an evening around the campfire.

Dr. Walter Piper, who heads the Loon Project and is a professor of biology at Chapman University in Orange, California, has been studying loons in northern Wisconsin for almost thirty years. During that time, he has seen a correlation between an increase in annual rainfall (a consequence of climate change) and a rise in the number of black flies. Consequentially, more black flies have led to loons abandoning their nests. In 2021, of the over one hundred nesting pairs of loons monitored, all but two abandoned their nests. This trend of loons abandoning their nests to escape the onslaught black flies has led to a high incident of chick mortality, and has contributed to the 22% decline in adult loon population in northern Wisconsin during the past 27 years.

As the climate continues to change in the boreal forests of northern Minnesota sights like this are becoming more common. Black flies, specifically the species Simulium annulus feed on the blood of common loons. The peak activity of this insect coincides with nesting season and the results can be disastrous, as in 2014 when an estimated 70% of nests failed because of this biting insect. Not only are the birds at the mercy of these flies on the nest, but any time they are on the surface of the lake; diving frequency increases and preening and resting decreases because of this insect. It is projected by as soon as 2080 the common loon will no longer summer in Minnesota as the southern boundary of suitable habitat of this bird will have shifted north and into Canada. This biome is where I focus the bulk of my work, specifically on the impacts of climate change.

Though it’s too soon to say for certain, it’s reasonable to surmise that what has happened with loons in Wisconsin could be happening to loons 200 miles away, near the Boundary Waters.

What makes northeastern Minnesota so unique and has made generations of people band together to protect and preserve the area is its water. The interconnected maze of clean lakes and rivers is what makes the Boundary Waters a jewel of the North American landscape. As these famously cold waters begin to warm as a result of climate change, we will see changing vegetation, impacts to water quality, and increased algal blooms affect the character of the lakes and degrade fish habitat.

Species like lake trout that need cold water are particularly vulnerable. Because they prefer deep water below 55 degrees Fahrenheit, the Boundary Waters is a natural, cold-water haven for lake trout. While they currently thrive in the Boundary Waters, scientists worry that climate change could result in lake trout disappearing from an estimated 30 to 40 percent of Minnesota lakes by 2050.

A larger worry comes from the future of a small fish you probably have never hooked.

Though not sought after by anglers, the impact warming waters will have on ciscoes, or freshwater herring, will have enormous consequences for sportfish. Ciscoes are at the foundation of the food chain, essential to populations of walleye, trout and smallmouth bass. For decades, researchers have watched their numbers decline throughout Minnesota.

A reason for this is that ciscoes thrive in water that is below 62 degrees Fahrenheit. Warming lakes are unable to support a stable population of ciscoes, and scientists have predicted that of the 620 current lakes in Minnesota home to ciscoes, 460 lakes will no longer support the fish by 2100.

As some researchers believe that a decrease in cisco numbers led to the dramatic collapse of walleye population in Mille Lacs, in central Minnesota, declining cisco populations could have a dramatic impact on sport fish in the Boundary Waters.

In coming years, we’ll likely see even more dire effects of runaway CO2 emissions on our lives and our surrounding environment. There will not be a place on the globe that will not be affected by climate change.

The Boundary Waters is no exception.

How soon the boreal forest retreats out of Minnesota, and the degree the ecosystem is transformed, depends on whether we can control carbon emissions and thereby, control warming.

If we continue the transition to renewable energy, stop deforestation, begin to rewild lands through planting trees and manage to achieve net zero carbon emissions by 2050, we can curb the impacts of climate change. This will take individual and communal action. It will mean advocating for aggressive carbon reduction policies and international cooperation. It won’t be easy, but we can meet this global challenge.

At Friends of the Boundary Waters Wilderness, we are working with other organizations, private companies, and government agencies on strategies to help the wilderness adapt to climate change. This could mean planting heat resilient spruce seeds in areas affected by fire to slow forest succession. It means preventing polluting runoff from mines and motors from degrading our water and making lakes more susceptible to harmful effects of a warming climate.

A canoe comes around the corner in the Boundary Waters, framed by a fading sun through the trees on the horizon.

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