Illinois' Natural Heritage
Prairie Grass Root System
In the early 1800s there were 22 million acres of prairie in Illinois, most of it concentrated in the central and northern portions of the state. Illinois was near the eastern edge of a vast grassland that covered central North America.
In northeastern Illinois, the prairie was interspersed with open woodlands called savannas comprised mainly of bur oak (Quercus macrocarpa) with a vigorous understory of grasses, sedges and wildflowers. This landscape was owed in large part to fires that swept across the land, typically in late fall or early spring. Fires maintained the open character of the landscape by killing young woody plants except for a few species that were fire-adapted such as bur oak and hazelnut (Corylus americana). Some fires were started by lightning, but many were intentionally set by the native inhabitants of the area. Native Americans burned the prairie for several reasons: to protect areas around encampments/villages from an unexpected wildfire, to herd large game to an area where they could be easily hunted, and to attract grazing game animals to the lush new spring growth of burned areas.
The early settlers assumed that the lack of trees in the prairie was an indication of inferior soils. They quickly learned that the black soils underlying Illinois' prairies were the most fertile in the world, but plowing through the thick prairie sod proved to be an extremely arduous task. The introduction of John Deere's polished steel plow, patented in 1837, made plowing the prairie relatively easy, speeding the pace of settlement. The proliferation of railroads in the 1850s opened the more remote areas to farming by facilitating the export of crops to market and the importation of lumber and other supplies. In the span of 50 years, most of Illinois' prairie had been converted to cropland.
With the nearly complete transformation of Illinois' prairie to agriculture, the scattered small fragments of prairie and savanna that remained were cut off from the natural processes that had shaped and maintained them over the preceding millennia. White settlers suppressed the fires that had been encouraged for so long by the Native Americans.
Domestic livestock were allowed to overgraze lands that had been only lightly grazed by wild animals. Plant species imported from other continents began to replace the native prairie and savanna species. Today, in most states of the tallgrass prairie region, less than 1 percent of the original prairie remains. In many cases, the total is 0.1 percent or less.
The future of the prairie is uncertain, but there are encouraging signs. Many prairie remnants are being nursed back to health through the removal of non-native weeds and the reintroduction of fire. Virtually every forest preserve district in northeastern Illinois is actively engaged in planting prairie reconstructions like those on the College of DuPage campus. Tall prairie grasses are being utilized on golf courses and corporate campuses to discourage large flocks of Canada geese from taking up residence. More and more homeowners are beginning to appreciate the beauty and utility of low-maintenance native landscaping. Prairie and savanna will certainly never again dominate the Illinois landscape as they once did, but perhaps they can remain a viable component of our environment.
Health and Sciences Division
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