By Marie Orttenburger
Illustrations by Spencer High
The brightly colored Karner blue butterfly favors a likewise brightly colored flower as its singular host plant: wild blue lupine.
Wild blue lupine thrives on dry, sandy soils in areas that range from open and sun drenched to partially shaded—conditions characteristic of oak savannas and pine barrens. To maintain these open habitats, disturbance that pushes shade-casting competitors out of the ecosystem is essential. In the natural world, that disturbance comes in the form of wildfire.
Fire suppression has reduced the kinds of habitat that support wild blue lupine and Karner blue butterflies to less than .01% of their original ground cover. Both species are declining, but the butterfly has it worse.
It is a federally endangered species. The butterfly’s Michigan stronghold—if you can call it that—is in a handful of counties on the west side of the state. Its numbers are dwindling fast—in no small part due to a century-long habit of putting out the fires that would have created the habitat it needs to thrive.
In addition to rarity, existing habitat is heavily fragmented by development. Unlike the familiar monarch butterfly, which travels thousands of miles each year, Karner blue butterflies can’t easily move from patch to distant patch. Without large sections of connected habitat, the species is vulnerable.
A little over a century ago, the Karner blue butterfly wasn’t boxed into disparate rooms across the landscape. When a patch of habitat became unsuitable for some reason, Karner blues could easily escape to greener—or, rather, bluer—pastures.
The same is not true today, and that presents a challenge for land managers hoping to restore oak savannas and pine barrens with prescribed fire.
The Karner blue butterfly needs a plant that needs fire, but it is itself a fire-sensitive species. If a fire is passing through its home, that butterfly needs to find a safe haven or it will die.
When land managers use prescribed fire to support habitat for this endangered creature, they leave patches of unburned land called “refugia.” It is a necessary measure to help a vulnerable species survive the treatment it needs to persist in a fragmented, warming world.
. . .
To understand how the changing climate influences fire in Michigan and elsewhere, it is helpful to know one of the first concepts those who work with fire learn in their training: the fire behavior triangle.
Not to be confused with the fire triangle, another fundamental concept that explains what it takes for most fires to ignite (heat, oxygen and fuel), the fire behavior triangle describes three key factors that influence how quickly and intensely a fire moves across the landscape.
One leg is topography: the slope of the landscape. Fire tends to move more quickly uphill and more slowly downhill.
Another leg is fuel: things that can be burned on a given landscape. Anything the fire can consume is fuel—the amount and kind of fuel dictates how fast and hot the fire gets.
The final leg is weather: relative humidity, temperature and wind speed and direction—not just on the day of the fire, but even in the weeks leading up to it—can all influence how a fire will burn on the land.
Over the past 200 years, people have dramatically changed two of those legs, which is changing how wildfires behave. Fire suppression and climate change are influencing the fuel and weather legs of the triangle.
“The U.S. has been really good at putting out fires for a little over 100 years now,” said Jessica Miesel, a forest ecosystem ecologist and biogeochemist at Michigan State University. “So over 100 years, we’ve been accumulating vegetation, and during drought, that vegetation is available as fuel for a fire.”
Add to that longer periods of hotter, drier weather courtesy of climate change, and you’ve got the recipe for record-breaking wildfires across the globe.
“These are the two key contributors to why we’re seeing fires that are larger, hotter and more severe in many areas of the world,” Miesel said.
In Michigan and other parts of northeastern America, the effects of climate on wildfire are not yet as clear. These areas just haven’t experienced fires that illustrate those changes.
“The big issue with fire and climate change is that the fire environment is changing, but it may not be realized until there’s an ignition,” said Michael Stambaugh, a dendrochronologist with the Missouri Tree-Ring Laboratory at the University of Missouri in Columbia.
“You don’t see Michigan’s fire regimes changing very quickly, but everything except for the actual fire is changing,” said Stambaugh, who studies the fire scars on tree rings to learn about early fire history. “The number of months it can burn, instead of being six, may now be seven or eight. The potential for crown fire, maybe historically it was 50%, now it’s 70%. You won’t see it realized until fire happens.”
But natural land managers must still determine how to support the continued health of the landscapes they care for—and the well-being of the people who live near them—as things inevitably continue to change.
“From the manager’s side, it’s a big unknown,” said Jack McGowan-Stinski, program manager for the Lake States Fire Science Consortium. “We’re kind of always on the tip of the knife. We’re having to try to manage lands with information we have but knowing there’s a whole lot of information we don’t have and aren’t going to get.”
. . .
Climate predictions are factored into planning for agencies like the Michigan Department of Natural Resources. The DNR’s most recent Forest Action Plan notes that climate change contributes to rising temperatures, decreasing snowfall, longer growing seasons and more precipitation in the spring and fall.
These trends, should they continue, define some likely winners and losers in Michigan forests. Moisture-loving and heat-sensitive boreal species like birch, red maple and aspen will struggle. Meanwhile, xeric species and habitats that are heat- and drought-tolerant, like oaks and tallgrass prairies, may be winners.
“These are considered pretty climate-resilient ecosystems, just based, I believe, on their natural ability to deal with prolonged drought,” said Nick Sanchez, a certified forester and conservation easement stewardship specialist with the Land Conservancy of West Michigan.
If you’re following along, you may wonder: Wait, wouldn’t that mean climate change might help create more habitat for the Karner blue butterfly? Aren’t mesic species overabundant in Michigan’s xeric ecosystems due to fire suppression, anyway? Could it even be a good thing that climate is likely going to reduce these species’ stronghold?
Climate change could have a role in restoring a balance that drastic landscape changes by European Americans disrupted. A century of fire suppression has enabled moisture-loving species to move into spaces where they had traditionally hung around the margins—spaces with soils that aren’t meant to hold moisture. In a future predicted to have more fire and more drought, it’s the fire- and drought-tolerant species that are expected to survive.
Faced with these outcomes, land managers must decide: Use fire to accelerate the removal of mesophytic species like red maple from ecosystems that are supposed to be xeric? Or let climate change take care of that and focus resources and time elsewhere?
“It’s the same line of reasoning but two completely divergent management scenarios or solutions,” said Justin Heslinga, stewardship director at the Land Conservancy of West Michigan. “We’ve even argued internally about what we should do there.”
These are the kind of questions that climate change forces land managers to answer. When it came to addressing red maple on the Land Conservancy’s preserves, Heslinga’s team made their call by taking a close look at what is happening on the ground. There are other factors driving the overabundance of red maple, and at least for now, it’s too much not to do something about.
“Deer preferentially choose other species over red maple, so abundance of deer is driving red maple, fire suppression is driving red maple—all evidence points to red maple on the increase, regardless of what climate predictions say,” Heslinga said. “There might be other pressures on the landscape that are swamping the effect of climate change, at least temporarily.”
The Land Conservancy of West Michigan will continue using tools including prescribed fire to push mesic, woody species out of habitats that are supposed to be more open.
The unknowns of climate change necessitate this kind of flexible approach.
“In Michigan, it’s still a pretty big question mark,” said Glenn Palmgren, fire management specialist with the DNR. “It’s clear that things are changing, but how they’re changing and how we react to that—I guess we’re just going to have to be nimble on our feet.”
“We don’t know what we should do. It’s going to take people trying things and learning. Practicing adaptive management, doing applied research, monitoring,” Leslie Brandt, a climate change specialist at the National Institute of Applied Climate Science, said during a panel discussion hosted by the U.S. Forest Service and the Fire Science Exchange Network.
“It’s going to be location specific, we’re going to have to constantly adapt as weather conditions change.”
. . .
Regardless of what the future may hold, fire has a role to play. McGowan-Stinski believes that to make the most of it, both land managers and the public will need to adapt their thinking.
In Michigan, managers who use prescribed fire may have to adjust their usual schedules. Climate trends are shrinking the favored burn windows for prescribed fire: Springs and falls (dormant seasons) are getting shorter and wetter.
McGowan-Stinski advocates that managers do more “growing season” burns during the summer.
“If our springs are potentially getting wetter, you may have to shift your burning out of your so-called spring season, because you don’t have a spring season that’s the same as it was a decade or two decades ago,” he said.
McGowan-Stinski also believes there is a need for a societal perspective shift on how the public think’s about fire—one that’s more akin to how we approach other natural disasters.
“With fire, we’ve created our own trap. With tornadoes, hurricanes and other large abiotic disturbances, we don’t try to stop them when they’re going. We have either a prep phase to reduce it, or a post phase to do the clean-ups and everything and prepare for the next one,” McGowan-Stinski said. “We need to get into that mentality with fire, too.”
What would it look like if the public, McGowan-Stinski proposed, “recognized that fire is just like rain?” What would it mean to build communities that aren’t at risk of being engulfed in flames when a fire happens in a neighboring forest—to effectively turn our homes into refugia amidst wildfire, as we do for the Karner blue butterfly?
“What tools can we use to set the stage so that when we have those wildfires, they’re not as catastrophic, or they’re not catastrophic at all, but just a wildfire?” he said.
Prescribed fire is one tool. It can reduce fuel loads in forests that haven’t seen fire for decades. It can also create a firewall between a forest that may one day burn and a community that needs to be protected. Both measures dramatically reduce the likelihood that a wildfire will result in the loss of lives, property or important habitat—and have the added benefit of reintroducing the ecological benefits of fire into systems that have been deprived of it for over a century.
It can also reduce the carbon emissions that intense, uncontrolled wildfires would otherwise unleash. Though it’s true that prescribed fire produces carbon emissions of its own, research has shown that it is less than the amount released by raging wildfires and is counteracted in part by the carbon sequestration prescribed fire promotes by supporting the regrowth of plants.
And the public appears to be coming around to it.
“We are seeing a big cultural shift in the acceptance of fire,” McGowan-Stinski said.
Continued improvement of public perception weighs in part on managers effectively mitigating risks. There is a degree of inevitability that out of all the prescribed fires applied, one will escape the boundaries of its unit. It happened this spring in Oscoda, during a Forest Service burn. The original prescription was for around 2,000 acres. It eventually burned nearly 6,000. No people or structures were harmed.
Brian Stearns, a Forest Service assistant fire management officer who focuses on fuels management in the Huron-Manistee National Forests, attributes this outcome to work he and his colleagues did on the landscape in years prior.
“All the work that we had been doing over the last few years protected two different subdivisions. The fuel breaks did everything that they were supposed to,” Stearns said. “The areas that we had treated with multiple entries of prescribed burning, the timber value was saved in those. Those areas that were never prescribed burned or only burned once all had severe crown fire. The severity was high enough that it was almost complete loss of the timber.”
All of that provides proof that prescribed fire works. From Stearns’s perspective, that is reflected in the local community’s attitude about it.
“Between that one and some previous incidents where our fuel breaks and prescribed burning had saved homes and communities, I would say for the most part, the folks that have been in the area look at it favorably,” he said.
Disclosure: The author is employed by the Land Conservancy of West Michigan.