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The Past is Our Lesson
Habitat Management Strategies at Portman Nature Preserve
No matter where they come from, everyone is here in large part to help create better habitat for a small brown butterfly and a plant that only blooms once in its lifetime.
Dressed in soiled yellow jackets and construction-style helmets and heavily laden with equipment, the burn crew slogs down a muddy trail through a dense thicket of bushes. Some have 40-pound packs of water strapped to their backs, others balance long-handled tools on a shoulder, and a few carry metal fuel cans. The mud has been churned into boot-engulfing black taffy that throws people off balance and into the hooked thorns of multiflora rose, or flailing for the relative safety of a poison sumac branch. But no one cares; it’s a sun-sparkle spring morning and they are here to set the wetland on fire.
The burn crew is made up of volunteers, SWMLC staff, and folks from Plantwise, a company that restores habitats and specializes in controlled burns. SWMLC has hired them to help burn portions of the fen wetland and oak woods at Portman Nature Preserve as part of its habitat restoration efforts. No matter where they come from, everyone is here in large part to help create better habitat for a small brown butterfly and a plant that only blooms once in its lifetime.
The women and men stop near a creek and the leader goes over instructions, using a radio to reconnoiter with another group stationed across the fen. They check the wind, their maps, strategize, and review the system of colored ribbons tied to plants that outlines the burn unit: pink shows the edge, green marks the “no-go zone” where the Mitchell’s satyr butterflies live.
The Mitchell’s satyrs live in the preserve’s fens, far away from Portman’s popular trails and lakeside views. They are homebodies, living their entire lives – egg, caterpillar, chrysalis, adult – in a small area among the tussock sedges and native shrubs. Sticking close to home was not a problem back when fires, set by lightning or the Potawatomi people, would sometimes burn slowly through the fen and keep the woody vegetation sparse. The fen and its inhabitants were adapted to fire and could handle it.
But conventional farm and forestry practices have put an end to fire, allowing non-native plants like narrowleaf cattail, buckthorn, and multiflora rose to invade the fen. They have smothered the native plants with their shade, hogged all the soil nutrients, and even altered the behavior of the water itself – changes that have put the Mitchell’s satyr down the road toward extinction. As brush closes in the walls of the formerly open prairie fen, it cuts off pathways for the butterfly to find new mates and habitat. Because of habitat loss like this, the worldwide range of these tiny brown insects has been reduced to just ten sites – and the fens of Portman are one of them.
A woman on the burn crew lights the tip of the spout of her fuel can. It looks incredibly dangerous, but it’s okay: the spout’s curlicue shape is an oxygen trap that prevents the stinky mix of diesel and gasoline from exploding. Without hurry, she dribbles a line of liquid fire alongside the moist muddy trail, which will serve as a firebreak in case the wind shifts. But it’s a calm morning and the air is barely moving. The only sounds are the crackle of dry sedges burning and the occasional squawk of radio communication.
Most of the vegetation doesn’t catch fire because the fen is still winter-moist. The flames move low and slowly enough to step over, except where they briefly flare around clumps of dried sedge. The buckthorn and multi-flora don’t “burn up” as one might wish, but they are probably scorched badly enough to set them back. Spots of bright orange flame are nearly hidden by the white and blue smoke that drifts away to hang further down the fen valley. The two fire crews slowly work their way through the thickets, laying fire and dousing any residual flames with water, until they meet and the job is finished.
After a brief reckoning, the crew gathers their tools and heads to the next burn unit. We walk the well-worn trail through the sunny spring woods, then stop to check out an area where SWMLC’s Stewardship Crew has been recently thinning trees. Dozens of skinny, thigh-high tree stumps stand among the tall oaks and hickories. The forest floor is littered with felled red maples, their gold and crimson flowers still valiantly fresh. It isn’t pretty, but it will get better – and it is another part of SWMLC’s habitat management plan for Portman Nature Preserve.
Suppressed fire is part of the forest’s history, just as it is for the fen. In fact, this dense shady forest may not have been here at all in the past. Instead, these big oaks and hickories are typical of light, open, dry woods that have evolved along with occasional fires. Their deep roots keep the trees from toppling in high winds and their thick bark protects their vital “heart wood.”
But modern fire suppression has changed the habitat here, too. Species that aren’t adapted to fire, like red maples and cherries, have crowded in among the oaks. Their dense shade is too dark for young oaks and hickories to grow well, and the un-burned shady ground holds more moisture, completely changing the dynamics of the woodland. Seedling oaks and hickories can’t get a good start in the forest gloom, and the distinctive set of understory wildflowers of an open oakwoods are mostly gone.
Like pulling back the drapes, cutting down the smaller red maples will let more sunshine reach the acorns and hickory nuts so they can have better chances to germinate and grow into the next century’s big trees. The twiggy tree tops left lying on the ground will be munched by deer and the branches will eventually rot and return carbon to the forest soil. Later, when spring sap is no longer flowing, the Crew will return to apply dabs of herbicide to the stumps to make sure they don’t resprout. Leaving the wood scattered like this, rather than in piles, will make it easier to do a future controlled burn. And burning a forest unit is exactly where the fire crew is headed next.
The northern shore of Mud Lake (which faces the viewing platform on the Yellow Trail) contains a rich ecological history. Several interesting plants and animals have been found here among the oaks and white pines: leadplant, a flowering shrub that’s usually found in prairies; American columbo, a sturdy wildflower that grows as high as seven feet over several seasons’ time, blooms just once, and then dies; and the Great Plains spittlebug, a rare insect that is also found in open prairies.
These finds indicate that this slope above the lake was once a fire-dependent, open habitat called a savanna, with scattered groves of oak trees, white pines, grasses, and sun-loving flowers. And with today’s burn, the columbo, the leadplant, and the spittlebug will experience their friend, fire, for the first time in 100 years.
Earlier in the day, while the fire crew was still going over the day’s plan, a small squad of Turtle Heroes set out into the frosty woods on Mud Lake’s northern shore to look for any sluggish box turtles that might have already awakened from their winter hibernation. The turtles are adapted to fire and can deal with small, creeping flames by hunkering down under logs and dirt – but extra care was taken with these long-lived creatures, just to be sure. SWMLC staff members Miko Dargitz, Nicole Speedy, and their families combed the woods, probed under logs, turned over fallen branches, and examined any freshly turned dirt looking for turtles – but didn’t find any early-birds. If they had, the Turtle Heroes would’ve taken note of their locations, whisked them into buckets, then returned them later after the burn was done.
Knowing the woods are turtle-free today, the fire crew feels safe in moving forward and again splits into two groups. Using the wide, hard-packed foot paths as breaks, a line of fire is laid along the inner trail and carefully monitored as it crackles through the dry oak litter. Meanwhile, another fire is set on the lake side of the unit. With the wind at its back and a hill to climb, this fire burns faster and a little hotter – but squirts from backpack sprayers and dampening blows from long-handled rubber flappers keep it corralled. Thick smoke makes it hard to see for a while. It’s visible from the viewing platform across the lake, creating an ethereal effect as it ghosts upward through the trees.
In the fire’s aftermath, small ash-devils whirl among thin streams of smoke, but the low intensity of the blaze has left the soil and tree trunks untouched. The fallen leaves and twigs that have burned will return carbon to the soil and – with the invasive plants scorched and set back – native buds and seeds now have air, light, and space in which to emerge.
The savanna has been reawakened.
Story and photos by Amelia Hansen (with Mitch Lettow), except Mitchell’s satyr butterfly (Geoff Cripe) and American columbo (C. Miko Dargitz).