When out of control, fire can be a truly destructive force. But for our natural prairies, savannas and other natural areas, it can be a priceless tool for preservation. Burn season is an important time of year to ensure that our natural areas come back in the spring better than ever.
Normally at this time of year, the leaves crunch beneath my feet and a sharp breeze fills my nose as my burn crew colleagues and I huddle in our Nomex jumpsuits, listening eagerly to the day’s burn plan. This time of year along 294, plumes of smoke rising high into the blue sky signal that fall is here. It’s a welcome break from the heat, and one reason I love fall. This year, my back hurt a little bit more with each shovelful of slushy snow. My shovel felt like it was made of aluminum foil. The leaves are buried, and Chicago’s blizzard has ended burn season before it could even begin.
While I couldn’t enjoy the season as I normally do in our area, I reached out to others from different parts of the country to help bring this burn season to life.
On Black Friday, I volunteered at Pleasant Valley Conservation Area in Woodstock with Greg Rajsky, volunteer steward, Morton Arboretum educator, and Nature Consultant with True Nature Consulting. Afterward, we took the time to discuss prescribed fire and answer the burning question: Why are the preserves going up in smoke?
Fire and Ecosystems
“We apply prescribed fire to bring back fire as an ecological function to the land. Our native landscapes burned with some regularity prior to the time of European settlement in the region. The Native Americans set fire to the landscape for a variety of reasons. Fires freely crossed the terrain until they met some kind of an obstruction. So, just about all of our native ecosystems are, what ecologists would call, fire adapted.”
Trees with thicker bark such as oaks are well adapted to burns. Prairie plants that evolved with fire prioritize the development of their roots, keeping an event such as a prairie fire from killing the entire plant. The energy in the root systems allows the plant to quickly re-sprout from the ashes during the next growing season. This evolutionary relationship between fire, ecosystem, and individual plant adaptations developed in our region until fire suppression became the policy of early settlers. I asked Greg about the effects of fire suppression.
“A lot of brushy areas of oak timber grew into copses and dense woodlots. A lot of the oaks had been top killed by the fire but had vigorous root systems underground while the above ground portion was shrublike. When the fires stopped, these oaks sprang into maturity. Many of these were harvested by the people in the area but there were other trees that started to move into the area during the period of fire suppression. Trees were limited in their range to the areas that did not burn, places along waterways, floodplains, ravines–places that burned less frequently or less intensely. A lot of the “weedy” tree species that we have with us today are those that are fire sensitive. Our oaks, hickories, walnuts, and some ash tend to be fire tolerant, whereas floodplain species like elm, silver maple, and green ash tend to be susceptible to fire. They do not survive the heat of the flames. Oaks especially have a close relationship with fire regiment. Oaks have thick, corky bark–especially bur oaks–that enable them to survive the fires even if they are top killed. The root system remains alive and allows the plant to resprout. Fire suppression changed the composition of our timbered lands, allowing the fire sensitive species, and shade tolerant species, to proliferate. They created shadier and more humid conditions, not conducive to the reproduction of oaks.”
Since development, it is undeniable that we have lost much of our natural heritage. Illinois, as a state, lost around 90% of its oak woodlands. Illinois was formerly 61% prairie. Only 5% of our wetlands remain. In addition to losing these lands due to agriculture and development, what we have left is altered still by fire suppression. An ecosystem not yet mentioned are oak savannas. In an earlier post, we touched on prairies, savannas, woodlands, and fire. Greg describes savannas here:
“It is a transitional ecotone between forest and prairie. It’s an area that would’ve been dominated by grasses but punctuated by trees. Sometimes large trees, but widely spaced. So instead of the closed canopy of forest, we would have widely spaced trees with ample sunlight beneath them and a mix of prairie plants, a few woodland flowers, and a mix of unique savanna flora. The savanna is supposed to have been a transitional space. One area could’ve been forested at one time and 200 years later it could’ve been a prairie.”
As you may have surmised, the trees populating savannas are the wide spreading bur oaks, the most fire tolerant of Illinois oaks. With frequent fire, savannas remained open. In the absence of fire, woody vegetation filled in. Savannas are rare, and only in recent times did their existence as unique ecosystems come to be. For an interesting read on the subject, look for Miracle Under the Oaks by William K. Stevens to learn the story of Somme Prairie Grove, located in Northbrook.
Prescribed burning through oak woodlands kills these fire sensitive species. Why is this good? What is it about oaks, hickories, and their woodlands that make it worth killing some weedier tree species? Isn’t there an ecological benefit to having more trees, fire sensitive or not? I again consulted Greg:
“These mesophytic, fire sensitive trees, have their place. Sugar maples belong in the ravines, in sheltered areas that are going to be a little more shady. The green ash, silver maples, and box elders belong in floodplains. But in the uplands and well drained areas, white oak, bur oak, and hills oak, are an important part of a vanishing ecosystem. Oak savannas and open oak woodlands represent habitats that were common two hundred years ago but are globally rare today. Besides which, the oaks and hickories provide ecosystem services. They enable functionality of these sites. Oaks are supportive of a wide range of other organisms. The critters that nest in the branches, the insect larvae that feed on the leaves, the other animals and fungi interact with the oaks. Oaks are considered to be keystone species. They also provide influence to the landscape above and beyond the numbers alone suggest.”
The act of fire preserves our rare ecosystems. Valuable to begin with, oaks provide more habitat to butterflies and moths than other native trees in the area. The rarity of healthy oak woodlands and savannas increases that value. If we lose the oaks, we may lose those insects, and then the birds that feed on those insects. It’s a bottom-up ecological effect that begins with the plants. To lose entire oak woodlands and savannas could have a devastating effect up the ecological chain. As far as invasive species go, native insects are not adapted to these newcomers, and even if we ignore their propensity to destroy native plant populations, they still provide less ecosystem services than any of our native trees, forbs, and grasses.
Fire as a Tool
By returning a fire regime to our remaining natural areas, we attempt to bring back the functionality of entire ecosystems. We effectively reduce populations of invasive species that prioritize reproduction over root development and prevent tree encroachment into our prairies. In our oak woodlands, we push back against saplings of fire sensitive species that are simply plants out of place. While these fires will not damage the larger of these sensitive trees, they prevent new growth. Oftentimes, these larger trees are removed mechanically or treated chemically. Through these practices, our rare oak ecosystems can persist and, ideally, reproduce under conditions that allow for the slow growth of oak giants.
Greg lays out the goal of fire as a management practice:
“We try to prescribe fire to the landscape commensurate with what would have happened prior to the period of fire suppression. The prairies would burn more frequently than the woodlands. But our woods still burn. Our deciduous trees would support a fire low and creeping along the ground not reaching the canopy. The fire would creep in a mosaic pattern, consuming the dried grasses, sedges, and leaf litter, but seldom consuming wooden plants.”
In my experience, woodland burns in the Midwest are calm when compared to prairie fires. As a tool, fire makes the work easier. Rather than needing to cut and herbicide every small invasive sapling, running a fire through the area would effectively kill these plants, making further woody management easier.
Besides providing control to fire sensitive species and invasive plants, fire provides ample benefits to the native species at hand. Greg goes into detail on what people can expect from a recently burned plot of land:
“A fall burn will remain black through the dormant season. A spring burn may see rapid changes. When the soil is blackened with soot and ash, and the leaf litter is removed, the early spring sunlight can warm the soil more rapidly there than in an area covered with duff and leaf litter. So the area that receives early sunlight warms rapidly and hastens the germination of native wildflowers and grasses. These areas that have been burned will green up much more rapidly than duff covered areas surrounding them. Throughout the growing season, you can expect the growth to be more robust and there to be a greater proliferation of flowering to be taking place. The burn hastens the recycling of nutrients into the soil and enables the plants to thrive very rapidly.”
Fire provides a pathway for nutrient recycling in a way that management without fire simply cannot do.
Before fire is put on the ground, there are steps to be taken to ensure safety is maintained. Greg explains:
“Many of these areas need to be under a permit issued by the IL EPA. There has to be an application, justification, maps, and pointing out structures, building, neighboring properties. All is taken into account before anything is lit. Fire breaks need to be installed and maintained so the fire is contained. Smoke management is a very important aspect, especially in areas closer to residential properties. The burn has to be conducted when temperatures, humidifies, wind speed, and wind direction are within set parameters. You have to have ideal conditions to conduct a burn safely.”
In any case, to burn an area requires months of planning and notifications. As Greg mentioned, smoke management is important as many preserves I have burned in are beside major roadways. This is where wind direction comes into play. We simply do not burn on days where the wind is likely to carry smoke into the roadway. The first step to keeping a fire contained is to burn within the parameters set. Akin to Goldilocks and the Three Bears, we cannot burn if it is too humid, too windy, or too hot. We cannot burn if it is too dry, not windy enough, or too cold. The specific numbers provide a range where fire can be contained safely.
Entire sites are typically not burned at once. To burn an entire preserve is to eliminate important winter food sources. Greg explains how burns are planned to mitigate these effects:
“Land managers establish burn units on a property so that not the entire woodlot or prairie lot would be burned in a given year. And this provides a refuge for insects and other animals to escape the flames. Oftentimes, the burning is done during the dormant season when insects have borrowed underground. They may be surviving as eggs in the stems of plants and certainly some mortality may take place, but that’s why you do not burn an entire plot. Portions are set aside to keep free from fire in a given year. And these units are ignited on a rotating basis. In one year, you’ll burn one section, in another year, another section. So the fire returns on a periodic basis to each area but seldom would any particular plot burn two years in a row.”
With fire there are risks, and these risks are largely mitigated through the preparation phase. A fire escaping containment is a risk that is mitigated through preparation and methodology.
A ring fire is the typical method of prescribed burning. The fire is lit along a burn break on the side of the unit opposite the wind direction. The fire is allowed to back burn against the wind into the unit while the fire is extinguished along the burn break itself. The torchbearers make their way up the sides, lighting as they go. As the fire back burns into the unit, it creates a burned out area that cannot sustain fire. When the ring is complete, the fire will race with the wind towards an already burned area. The fire will then eventually fizzle to a close and the burn is complete.
Prescribed Fire and Climate Change
When looking at a burn and all the smoke, one wonders how this affects our climate. Greg gets this question frequently. In light of the release of the fourth National Climate Assessment on Black Friday, Greg had this to say.
“Is it a good idea to burn these areas because of the release of carbon in the atmosphere, especially in light of climate change and concerns of our climate footprint? Overall, the benefit exceeds the risk. The burn transpires very quickly. The amount of carbon released into the air is negligible compared to the amount that is returned to the soil where it is sequestered, and actually more effectively removing carbon from the atmosphere. There is some release, but there is also sequestration that takes place.”
In addition to returning carbon to the soil, that carbon is utilized in the build up of a rejuvenated prairie or woodland habitat, further sequestering carbon in a more efficient manner.
Frederick Reuter, an organic farmer out of Virginia, reached out with some prescribed burn photos as well as a background as to the benefits of burning their farm fields. To summarize, organic farmers burn to eliminate the need for pesticides in order to promote insect diversity as well as to reduce machine compaction on the soil. In the Midwest, we use prescribed burns as a way to effectively return nutrients to the soil as natural fire did prior to European settlement and to reduce weedy species populations, allowing natives to flourish and reclaim their ground. These principles are applied by Frederick as an organic farmer, but he takes it a step further. Reduced machine compaction and machine usage in general lowers his own carbon footprint as well as provides for a healthy crop.
Frederick utilizes fire to improve bird habitat in the woodlands as well. He is taking a page out of the handbook of the Native Americans. Native Americans used burns to improve hunting grounds. The rapid-fire greening up of a burned field in spring was a beacon for grazers to the benefit of the hunters.
From the Ashes
A destructive force such as fire provides a service to Midwest ecosystems. From the ashes rises resilient prairie species to promote biodiversity and maintain our natural heritages for the enjoyment of future generations. Our oak woodlands remain clear of weedy species, allowing oaks and hickories to reproduce and maintain themselves and the community that relies on them. Prescribed burning is a valuable tool to be welcomed as we work to preserve our natural heritage. Now let’s just hope we can get fire on the ground this spring.
Gregory Rajsky is a site steward at Pleasant Valley Conservation Area in Woodstock for the McHenry County Conservation District. Feel free to join him or other stewards for MCCD at a number of natural areas. Click the link for information on sites and schedules. Greg would be happy to have you.