Portrait of a forest on the edge of the climate


Around the world, climate change is reshaping habitats that are already at their limits. In northeastern Minnesota, near the Canadian border, lies a boreal biome at the southern edge of its climatic range. This band of mixed coniferous forest now transitions to temperate forest in the south of the state, and drier forest and grassland in the west. Warmer winters, longer and hotter summers, and more variable precipitation ranges are currently transforming this boreal zone, and these changes have profound implications for the region’s vegetation and wildlife.

Benjamin Olson began photographing this ecosystem in 2008 at the age of 19, which allowed him to notice and document these slow changes. “The changes in wildlife, landscape and weather patterns that I have observed are significant,” he says. “What drives me when it gets too much is this: we are witnessing a major ecological shift in our lifetime. While it is depressing in some ways, I find it quite fascinating.

Consider the Boundary Waters Canoe Area Wilderness, the nation’s most visited wilderness, and the surrounding Upper National Forest. Boreal conifers have long thrived there. But over the next century, if climate change continues unabated, models predict the ecosystem could yield all or part of the ground to temperate forest or even savannah, says Lee Frelich, director of the Center for Forest Ecology at the University of Minnesota. Today, broadleaf deciduous trees, including temperate forest species like red maples, are increasingly taking root after blowdowns, wildfires, and other disturbances. Red maples are relatively few in number now, but they are a notable growing presence for experts who know these places deeply.

Climate-sensitive birds, such as the spruce grouse, which feed exclusively on short coniferous needles in winter and form shelters by diving under the snow to stay warm and hide from predators, and the willow tit, one rare year-round boreal songbirds, are among the state’s endangered bird species.

“The spruce grouse is a species that really depends on coniferous forests. In Minnesota, we’re on the edge of the boreal region, and we expect it to move north with climate change,” says Charlotte Roy, a research scientist with the Minnesota Department of Natural Resources who undertakes an in-depth study game bird populations and habitat requirements in the state. “At this point, we’re really trying to figure out: what does this species need and how might that be affected by a variety of different factors?” Not only is grouse habitat shifting north, she says, but warmer winters are causing snow to melt and refreeze. This creates layers of ice that can make it harder and more dangerous for grouse to dive for shelter.

Mammals can also be affected. For example, because spring snows melt earlier, scientists believe that the snowshoe hare’s white winter camouflage could be more and more mismatched with the season, making them easier prey.

Common loons, an icon of the upper Midwest, face many threats, such as ingesting lead fishing sinkers. But warming temperatures and changing rainfall patterns are upping the ante in myriad ways, including increasing black fly populations.

Birds don’t abandon their nests easily, but when they do, fly attacks (pictured below on the north shore of Lake Superior) are often the cause, says Minnesota scientist Walter Piper. National Loonie Center and professor at Chapman University. His data from the past decade shows that Wisconsin loons more often abandon nests during years of black fly abundance, contributing to local declines. Now he’s expanding his research to understand if that’s true in Minnesota. If global warming reaches 3 degrees Celsius, which could happen as early as 2080, Audubon climate models project that common loons could almost entirely leave the land of 10,000 lakes.

Land and wildlife managers in the boreal zone of Minnesota are actively considering how to build resilience in ecosystems to help them withstand stress from insect invasions, extreme weather and warming temperatures, as well as to help trees and animals. species move and adapt. For example, in 2021, unusually severe drought-fueled wildfires burned in the Upper National Forest. Conservationists and scientists have been monitoring the regrowth. In an experiment using a strategy called assisted migration, the Nature Conservancy this summer work with officials to reforest trees they hope can tolerate a warmer future.

In the Beltrami Island State Forest, located on the drier western boreal edge of the state, one of many coping strategies is to increase tree species diversity within and between forest stands. “If we lose a species, at least we’ll still have a forest,” says Charlie Tucker, wildlife supervisor with the Minnesota Department of Natural Resources Division of Fish and Wildlife.

Tucker and his colleagues have already identified several climate-sensitive birds, including spruce grouse and willow tits, which they actively manage and monitor on Beltrami Island. Grouse live there in the highest densities in the region’s thick jack pine forest, where they eat conifer needles, but these habitats can turn into thinner forests as the climate dries out. “If jack pine doesn’t regenerate as well in drier scenarios, that doesn’t bode well for spruce grouse in this region. We suspect they are already experiencing a northward range contraction, but data is lacking, other than anecdotally,” he says. Conversely, although there are no Kirtland’s Warblers in the Beltrami Island State Forest currently, in the future there may be plenty of suitable woodland habitat for them, he says. Managers there are also experimenting with timber harvesting patterns in parts of the state forest to see how best to help birds that may be vulnerable.

Some of Minnesota’s species are engineers of their own destiny. Beavers are highly adaptable mammals that scientists believe will cope just fine with global warming. When extreme flooding occurs, as it did statewide in 2022, beaver dams help build the region’s resilience by storing sediment and filtering water. These structures even shape the flow of water over the landscape decades into the future, recent search from the University of Minnesota shows Duluth. And wherever beavers do their work in a forest, wetlands follow, creating habitat that attracts different types of avian species, including wading birds like the Great Blue Heron and a variety of waterfowl.

This photo essay was originally published in the Fall 2022 issue under the title “On the Edge”. To receive our printed magazine, become a member in donate today.


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