It clears away foreign vegetation, releases nutrients for native plants and opens paths of sunshine to sprouts. Centuries ago, when most of Illinois was tallgrass prairie, racing fires that groomed the land for regeneration were common phenomena. Today, less than 1 percent of the state's land is defined as prairie, and only a fraction of that has escaped alterations through human activity. Nyberg has participated in or supervised more than 20 controlled prairie burns in different locations. Woody, as opposed to grass-stemmed plants, can overwhelm a prairie.
Fire is a quick and effective control.
We're not willing to let things go as an experiment to find out if that will happen. Vast prairie fires were historically sparked either by lightning or by humans. Nyberg's Chicago prairie burns follow strict controls. Burns are scheduled about 36 hours in advance, based largely on weather forecasts. The prairie grass is set alight upwind, then the fire progresses along a path, leaving in its wake a charred but cleared field.