Thursday, March 30, 2006

Prairie Fire, Now and Then

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[Note: A technical glitch kept this spot from airing on WILL at 4:45 on March 30, so it is set to run at 4:45 and 6:45 on April 6.]

On a recent Sunday afternoon, I joined up with thirty other volunteers to set a fire. Our goal was to burn three years worth of dried growth on part of a restored prairie owned and managed by the Barnhart family south of Urbana. [Click to visit the Barnhart Prairie website.] Actually, it took only one person armed with a kerosene drip torch to light the fire; the rest of us spread out along the line where he passed. Our job was to make sure no flames or sparks crossed the mowed path that served as a break to contain it.

The vegetation we were burning was dry as could be, and a steady breeze pushed the fire along right where we wanted it to go. Where the plants lay down the fire rippled over the ground like waves on a burning lake. Where the dry stalks stood upright the flames roared skyward, a tower of heat and light. In the wake of the fire, the smoke cleared quickly, and the thin layer of ash that remained smoldered very little. Looking on the newly cleared ground was like looking at a newly planted garden, with all of the hopeful anticipation that involves.

What the Barnharts are working to restore is tallgrass prairie, a relatively small patch of the ecosystem that dominated central Illinois from about eight thousand years ago until the coming of European settlers and the advent of modern agriculture in the nineteenth and twentieth centuries. Since the 1820s, more than ninety-nine percent of Illinois’ prairie has been converted to cropland or urban uses. [To learn more about prairies, visit The Tallgrass Prairie in Illinois by Ken Robertson, botanist with the Illinois Natural History Survey.]

Historically, the flora of the tallgrass prairie was characterized by a tightly packed mixture of more than three hundred species of grasses and flowers, many of which grew ten feet tall, or more.

In combination with climate and grazing, fire was one of the primary factors that accounted for the existence of prairies where forests might otherwise have dominated the landscape. Sometimes caused by lightning and other times ignited by Native Americans, prairie fires are estimated to have burned any given parcel of land once every one to five years.

Prairie fires moved quickly, so their heat did not penetrate deep into the soil. Thus they killed the saplings of encroaching trees, and favored instead the growth of herbaceous perennials, plants that die back and store their energy below the ground in winter.

By removing thatch and speeding the return of nutrients to the soil in the form of ash, prairie fires enabled dormant seeds to germinate. The spring and summer following a burn were marked by a profusion of flowers and reinvigorated forage.

Prescribed burns are used now in the management of prairie remnants and restorations to achieve similar effects.

Although fire has proven an effective tool in efforts to maintain and restore prairies, it should be emphasized that we’re still learning how best to use it. For example, some seventy-five percent of all the species of organisms found in a prairie are insects or their close relatives. Many of these creatures overwinter in the dead stems of prairie plants, and are thus wiped out in a burn. This loss may not have constituted a disaster back when the size and make-up of prairies guaranteed sufficient insect populations to re-colonize burned areas. But in today’s highly fragmented landscape, where prairie remnants and restorations are small and disconnected, it takes careful planning to ensure that there are bugs enough nearby to truly bring a prairie back to life.

And bringing the prairie back to life—even if it’s in a small way—is the goal of the prairie fires we set today.