Prairie: A Natural History of Pyromania was originally published in the BFEC Newsletter, Vol. 13/No. 4, Fall 2009.
It is early August and you have passed through the arches of silver maple by the BFEC farmhouse. The trail in front of you takes you into a scene very different from the woods and farmland of Knox County. You are entering our seven-acre restored prairie.
Grasses reaching eight feet or more and the taller stalks of prairie dock and compass plant (see page 5 of original newsletter) with their large, yellow flowers captivate your attention. Shorter grasses with feathery flowers cover most of the area. Scattered islands of purple, pink, and yellow flowers are scattered among the grasses. Notable is the absence of trees and woody shrubs. This is a special community of plants with few species in common with the second-growth colonizers of abandoned cropland.
You might ask (as many people do), “Is this really a natural feature of Ohio or Knox County?” The answer is more complicated, and more interesting, than you might have guessed. The short version is that prairies once covered nearly two-thirds of what is now Ohio. For the last 4,000 years however, management by humans allowed for patches of prairie in a primarily forested landscape. When immigrants came to Ohio in the 18th century, about 4 percent of Ohio still supported prairies. Let’s fill in some details to better understand this short answer.
The species of plants in an area and their form of growth define “prairie.” In the tall-grass prairies that grow in Ohio and further west to Iowa, grasses, especially big bluestem, little bluestem, indiangrass, and prairie cord grass cover most of the ground. Non-grass flowering plants (“forbs”) fill out the prairie community, but are short in stature and not woody.
One common feature of prairie plants is that most of their structure is underground. For example, the spectacular flowers of blazing star barely reach your knees but its roots can reach fourteen feet deep! These deep roots allow prairie plants to reach water in periods of drought. Also, prairie plants survive winter by storing energy in underground stems. Placing most of their resources underground, however, creates a limit to prairie plants above ground growth — the woody structure needed for height is sacrificed to subterranean stockpiling. As a result, if trees enter prairies, the shade they cast will cause typical prairie plants to disappear.
About 8,000 years ago and after the retreat of the last great glacier of the Midwest, the climate of Ohio became much hotter and dryer than we now experience. Conditions were perfect for prairies to dominate, and they did just that through much the area from the Rocky Mountains through Ohio and into Pennsylvania. The prairie period lasted 4,000 years, so prairies were indeed locally “natural” for quite a long time! The people who lived in this area learned how to thrive in the prairie landscape.
The climate became cooler and wetter starting about 4,000 years ago, and this change favored the growth of trees. As trees shaded more land the prairies retreated. People began to burn some areas to maintain the prairie habitat. Burning is effective as a tool for management because fire kills the woody tissue of trees but leaves intact the vital root systems and underground stems of prairie grasses and forbs. The hottest prairie fire barely warms the soil just an inch under the surface.
In Ohio, some of the largest areas of prairie that were maintained by Native Americans were Darby Plains (near Columbus), Sandusky Plains (just northwest of Knox County), and two areas in northwest Ohio. Early settlers throughout Ohio, including in Knox County, observed many smaller patches of prairie as well.
In modern times, “prairie management” still means regularly burning (or mowing, a modern invention) to suppress the growth of the woody plants. Without management a prairie would undergo succession to forest in a couple of decades or less. At the BFEC, we try to conduct controlled burns once a year, in late March or early April. These burns are done with the planning and supervision of trained people (don’t attempt this at home!). We have to wait for just the right combination of dryness of plants, air temperature, moderate wind and correct wind direction. We also obtain permits from the OEPA and the Ohio Division of Forestry, notify local police and fire departments, file a detailed plan for the burn, and organize a crew of volunteers to monitor and manage the fire. Once the main fire is set, though, only running out of fuel will stop the burn (which is why we make sure the edges do not have fuel).
The burn creates excellent conditions for the prairie plants to get started in the spring. Nutrients previously stored in stems are returned quickly to the soil — no waiting for those pesky slow fungi and bacteria to break down dinner! The blackened surface of the soil absorbs heat from the sun, promoting sprouting of the new growth from underground stems. Green plants push above the soil within a week or so of the controlled burn, and the new growth cycle is started.
Most of Ohio’s prairies were converted to farmland and housing projects, but prairies are coming back to our area. Farmers and other landowners, park commissions, and nature centers increasingly are reestablishing prairie habitats. In addition to the BFEC prairie, you also can experience this habitat at the Wolf Run Regional Park just east of Mount Vernon.
Why are people making this effort? Prairies, with their diverse plants and animals are beautiful and fascinating, and this diversity would fade away without some help. Prairies are an integral part of both our natural and human history, and we would be culturally diminished by their loss. More functionally, prairies protect soil and watersheds by limiting erosion and by building organic matter back into depleted, old farmland soils. And, let’s be honest, watching a big, safe burn once a year is as exciting now as it must have been 4,000 years ago.