. The changing Illinois environment : critical trends : technical report of the Critical Trends Assessment Project. Man; Pollution; Environmental protection; Ecology; Environmental impact analysis. >90% 80-89% 70-79% 60-69% E3 50-59% [J3 40-49% E3 30-39% (3 20-29% ? 10-19% ? <10% Figure 3. Percentage of each Illinois county that was prairie in 1820 (Source: Iverson 1989). (Bogue 1968). A difficulty was that the prairie sod was so dense with tangled roots and deep that available plows were not able to break it easily. Prairie sod could not be broken easily until 1837, when John Deere, liv
. The changing Illinois environment : critical trends : technical report of the Critical Trends Assessment Project. Man; Pollution; Environmental protection; Ecology; Environmental impact analysis. >90% 80-89% 70-79% 60-69% E3 50-59% [J3 40-49% E3 30-39% (3 20-29% ? 10-19% ? <10% Figure 3. Percentage of each Illinois county that was prairie in 1820 (Source: Iverson 1989). (Bogue 1968). A difficulty was that the prairie sod was so dense with tangled roots and deep that available plows were not able to break it easily. Prairie sod could not be broken easily until 1837, when John Deere, living in Grand Detour, Illinois, invented the self- scouring, steel-bladed plow. It can be said that the economic development of Illinois depended on the conversion of prairie soil to agricultural and eventually urban uses. In terms of overall land use, Illinois ranks 49th among the 50 states in the percentage of natural vegetation remaining (Klopatek et al. 1979). It is impossible to document today exactly how rapidly the prairies were plowed. One estimate is that of the prairies in the state were plowed each year (Page. Figure 4. Changes in Illinois prairie acreage by county. The fust number is the number of acres of prairie in 1820; the second is the number of acres of high-quality prairie remaining in 1976. Data for 1820 from Iverson (1989); 1976 data from White (1978).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Illinois. Dept. of Energy and Natural Resources; Critical Trends Assessment Project. Springfield, Ill. : Ill. Dept. of Energy and Natural Resources
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