Why We Burn
by David Hoyt
About eighty miles southwest of Chicago on Interstate 55 is a small farming town that most travelers probably never notice. Dwight, Illinois is a convenient stopping place for my family on regular road trips to visit downstate grandparents. For the dog, it is a chance to take care of business. For my kids, it is an opportunity to eat at the McDonald’s just off the interstate exit. For me, Dwight is where the swampy shrub land and endless logistics warehouses of the Des Plaines and Kankakee River valleys make way for the broad, uncluttered horizons of the Grand Prairie.
Dwight also happens to be where the eldest son of Queen Victoria, the future Edward VII, King of Great Britain and Ireland and Emperor of India, saw a raging prairie fire. The year was 1860, and Abraham Lincoln had just been elected president. So unusual and impressive was the spectacle, both of the prairie itself and of the prairie on fire, that Prince Albert Edward’s stay in the grassland hamlet of Dwight was remembered as the personal highlight of his tour of Canada and the Eastern United States.
The fire was preceded by a fearsome, late summer thunderstorm. The onset of the storm that evening would be familiar to any modern Midwesterner; the aftermath, less so. First, a blackening of the night sky, then a roaring wind, followed by several minutes of torrential downpour, during which the skies around Dwight were curtained with lightning bolts. Then, on the western horizon arose three glowing patches of orange light. After several hours, they merged into one glowing belt. Prince Albert’s party rode out for a closer view, as described by London Times reporter N.A. Woods in 1861:
For a mile and more before you reached the edge of the fire you were in its bright orange light, which made everything as visible as if it were noon day, and the sun was shining fiercely through a blood-colored haze. You could hear the sharp barking howl of the prairie wolves as they rushed away for the darkness, and see the prairie hens fluttering and fluttering from place to place, turning in their wild terror full into the smoke, when they fall and perish instantly. At last you gain a little rise and look beyond into such a scene as nothing but a prairie fire can show. It spreads out a sea of red smouldering ashes, glowing for miles in all directions, while the deep white ridge of flames a-head mount the slopes with awful rapidity, and flap their heavy tongues up into the air with a hoarse roaring noise that fills you with astonishment and almost terror. Hour after hour you may stand, fascinated with the terrible beauties of the scene, as the mass of red sultry ruins grows and grows each minute, till your eyes are pained and heated with its angry glare, and you almost dread the grand, fierce sheet of fire, which has swept all trace of vegetation from the surface of the prairie... [T]he glare was tremendous, as if the world itself was burning.
For a brief period of time, between its initial seizure by European settlers and its eventual subjugation to the plow, scenes such as this one made Grand Prairie and the lands further west the playground of nineteenth century European princes. Far from being flyover country, it was an American Serengeti, its wildlife moving across the landscape on a scale unmatched anywhere apart from east Africa. Fire was an integral part of it. Great herds of bison quickly moved onto expanses charred by conflagration, where they sought the tender sprouts of regrowth, rich in the protein required to sustain their massive frames. Where the bison went, the land was transformed—kneaded and spaded, the seed bank churned so that what had lain dormant in the shade of tall grass and its flammable thatch would have a chance to see the light of day, favoring different species of flora, insects, and birds.
As vivid as the above account is, it yields a misleading impression of the role played by fire in a typical Midwestern ecosystem. Prince Albert and his cortege confronted what they perceived to be an empty and primeval landscape, in which sublime natural forces played themselves out in the absence of human interference. This notion is deeply rooted in the American experience of nature, is central to the history of the American conservation movement, and is a fundamental distortion. This is made clear by the history of fire.
Although Prince Albert’s prairie fire appears to have been struck by lightning, and many fires undoubtedly were, the consensus among researchers today is that over historical time, natural fires were a minority. Over the course of human history, anthropogenic fire has been the rule. Humankind brought fire to the land from the beginning. The central Illinois landscape experienced by the British heir-apparent as a sportsman’s playground was an abandoned one, forcibly emptied of its indigenous inhabitants little more than a generation before. They, as is uniformly attested to by the earliest travel accounts, burned deliberately and often.
In Illinois, the retreat of the last glacial ice sheet some 10,000 to 12,000 years ago was an ecological reset of the most extreme proportions. It was also the moment at which Homo sapiens arrived on the scene. The landscapes and ecologies that evolved afterwards cannot be disentangled from human activity. Since that time, within the broad parameters set by post-glacial climate and geology, the features of Illinois’ ecosystems have been shaped as much by fire-bearing humans as by soil, temperature, or precipitation. The sunny, open oak savanna and the wide-open varieties of prairie both require frequent burning to maintain their assemblages of plants and animals. The spark to set them aflame was provided by humans.
Bringing fire back to the landscape is thus not about restoring a purely natural process. It is about restoring a lost human practice. An oak savanna, and the ecological relationships that nest within it, may be as much an artifact of previous human activity as an arrowhead or an effigy mound. As fire historian Stephen Pyne writes of savanna:
The open landscape was often a more desirable one. On it ungulates could browse and graze; across it hunters and warriors would watch for prey or raiding parties; and over it tribes could travel untrammeled…Keeping woods free of underbrush, burning back scrub, and quelling fuels were all means of cleaning up the countryside, or exercising the rights and duties of biotic citizenship.
Perhaps the most compelling evidence for the primacy of anthropogenic fire on the Midwestern landscape is the persistence of what is called the “prairie peninsula,” a tongue of land that breaks off from the Great Plains to the east of the Mississippi River, mapping an area somewhat as molasses might if spilled over the rim of a bowl and onto a gently sloping continental plate, until it covers most of Illinois, the center of Indiana, and as far as west central Ohio.
Most of this region can be farmed without irrigation. In the absence of agriculture, such moist conditions would naturally favor deciduous forest. Indeed, early speculation as to the origins of the prairie turned on the level of precipitation found in a given region. Where it became too dry to support forests, so the argument went, in a debate reaching back to Thomas Jefferson and John Adams, prairie of one form or another would naturally establish itself. (Jefferson felt that the constant burning activity of Native Americans was responsible for the prairie landscape).
The existence of the prairie peninsula presents an anomaly for this line of argument. Why is it there if conditions east of the Mississippi are moist enough to support forest? In a further twist, climate records indicate that, after a long, post-glacial drought that favored grasslands in the plains and Midwest, conditions some 5,000 years ago then became cooler and wetter. For example, in a 2020 Holocene paper, researchers show that cooler and wetter conditions during 1500–1820 in Missouri did not correspond to a reduction of prairie grassland in the areas occupied by the Osage people. Something—or someone—kept the fires going, even when wetter local climate conditions began to discourage them.
Similarly, with regards to the oak savanna ecosystem represented in several Cook County Forest Preserve tracts, recent research by Stephen J. Tulowieki et al. suggests that habitats like it are a legacy of “Native American land use,” or NALU. Oaks as a genus are naturally fire resistant but shade intolerant. They flourish when they can grow outward unimpeded and in full sun. If competing species, such as maples or beech, become too numerous, they deny oak saplings the light they need to establish themselves and thereby “shade prune” them.
In order to reproduce, oak forests rely on fire to eliminate competition from shade tolerant but fire sensitive species such as maples. Another way of looking at the dynamic is that, left to its own devices, an oak savanna would revert to a maple-beech forest. The fact that historical records indicate widespread presence of oak savanna in northeastern Illinois since first European settlement suggests that fire maintained these ecosystems.
Even if the consensus is growing that anthropogenic fire fundamentally shaped two of the characteristic ecosystems of northeastern Illinois—prairie and oak savanna—many difficult questions remain as to how contemporary burning should be conducted. Native American fires were anything but random or uncontrolled. The prairie fire witnessed by Prince Albert was most likely what Stephen Pyne would call “feral”: a naturally-caused fire set in a landscape gone fallow after a generation of neglect following the removal of Illinois tribes in the 1830s. All the evidence indicates that Native Americans burned often and with a purpose: to clear a berry patch, to establish fire breaks around villages or crops, to expend excess fuel, to hunt and flush game, and to manage the seasonal movement of the bison herds.
Modern burning necessarily has other objectives, but they must be no less defined than their Native American precedents. According to Nature Conservancy ecologist Chris Helzer, the fact that fires inevitably destroy plants and kill animals, even within closely controlled quarters, means the most important principle is to burn in patches—so-called “patch burning,” which never burns more than a quarter or a third of a tract at once, so as to allow vulnerable, slow-moving organisms such as invertebrates, reptiles, and amphibians a refuge from which they may later recolonize a site.
In smaller, fragmented areas, however, it can be difficult to contain a burn in such a way. When a rare species is present in a small preserve—a butterfly, for example—a poorly-run burn can extirpate it entirely. Grassland birds in particular have sometimes conflicting habitat requirements that can be severely affected by fire: birds like Dickcissels, Henslow’s Sparrows, or Sedge Wrens do best in the thick layers of thatch found in older, undisturbed prairies. Grasshopper sparrows, on the other hand, prefer just the opposite: the mixture of short grass, open ground, and minimal thatch achieved by frequent burning. Plovers, like Karner Blue butterflies, prefer just-burned ground.
How are all these competing needs to be managed within a regime of prescribed burning in ever shrinking habitats? In the end, as we carry an ancient land management practice forward into the twenty-first century, an accurate understanding of what wildlife a habitat supports is the crucial prerequisite to any burn strategy. Simply lighting a fire at the same place at the same time every year may not be the best way to build the diverse and resilient ecosystems that Native Americans maintained and early settlers marveled at. But even outfitted with the best knowledge, greatly reduced habitat areas can force difficult trade-offs: Control an invasive species, or preserve non-natives used by migrating warblers? Restore a suppressed oak savanna glade, or maintain a closed canopy forest inhabited by Wood Thrush? Protect of a vulnerable species, or promote overall diversity?
As Helzer writes on his blog, the Prairie Ecologist, there are no right answers about how to burn, just tough decisions. The one thing there is no avoiding is fire itself. Humans have been doing prescribed burns for millennia, even as the climate changed around them. The brief episode of systematic fire suppression that peaked in the early twentieth century was a historical anomaly. The more burning we do, the more diverse and resilient our prairies and forests will be, as the climate continues to change around us once more.
Sources:
N.A. Woods, The Prince of Wales in Canada and the United States, (London: Bradbury & Evans, 1861), 304.
Stephen Pyne, Fire. A Brief History. Second Edition. (Seattle: University of Washington Press, 2019), 51.
William P. Nanavati and Eric C. Grimm, “Humans, Fire, and Ecology in the Southern Missouri Ozarks, USA,” The Holocene Vol. 30:1 (2020): 125-135.
Stephen J. Tulowieki, David Robertson, and Chris P. Larsen, ‘Oak Savannas in Western New York State, circa 1795: Synthesizing Predictive Spatial Models and Historical Accounts to Understand Environmental and Native American Influences,” Annals of the American Association of Geographers Vol. 110:1 (2020): 184-204.
Chris Helzer, The Ecology and Management of Prairies in the Central United States, (Iowa City: University of Iowa Press, 2010); Stephen Pyne, The Great Plains: A Fire Survey, (Tuscon: The University of Arizona Press, 2017).
Chris Helzer, “Difficult Decisions – Growing Season Fires and Other Prairie Management Choices,” The Prairie Ecologist, June 11, 2013. https://prairieecologist.com/2013/06/11/difficult-decisions-growing-season-fires-and-other-prairie-management-choices/