The Biogeography of and Habitat Loss on Hill Prairies

Abstract

According to Evers (1955) the term hill prairie was first used by A.G. Vestal in the 1940s during his ecology classes and seminars at the University of Illinois. Hill prairies, as defined by Vestal, are islandlike prairie openings occurring on steep slopes, typically river bluffs, that are (or were) otherwise forested. Hill prairies have also been called bluff prairies, goat prairies, and prairie openings (Robertson et al. 1995). The distribution of hill prairies extends from the upper Mississippi River Basin, in central Minnesota (Olson 1989) and Wisconsin (Shimek 1924), to southern Illinois (Evers 1955), and in Missouri (Steyermark 1963), Iowa (Cooper and Hunt 1982, White and Glenn-Lewin 1984), and parts of South Dakota (Novacek 1985) primarily along the Missouri River. Four basic types of hill prairies are recognized based on soil substrate: (1) loess, (2) sand, (3) glacial drift, and (4) gravel hill prairies. The research described here focuses on loess hill prairies within Illinois. Loess hill prairies are the most frequent type within Illinois and occur along the Mississippi River, the Illinois River from its junction with the Mississippi River to Putnam County, and along with the Sangamon River in Cass, Menard, and Mason Counties (Evers 1955, Kilburn and Warren 1963). Glacial drift hill prairies occur in Coles and Vermilion Counties of east central Illinois (Reeves et al. 1978, Ebinger 1981). Before European settlement, it is likely that hill prairies never formed large continuous segments in Illinois but were fragmented by ravines that dissect the river bluffs and slopes, and delimited on the upland sides by forest