We examined the response of prairie forbs to deer browsing by counting stems of forbs in plots protected from deer browsing and unprotected plots at Goose Lake Prairie State Park, Morris, Illinois. Sampling of the plots occurred in 1992, 1993, 1994, 1997, 1999, 2000, and 2001. Using Detrended Correspondence Analysis we ordinated plot data using the data collected each year from protected and unprotected plots as separate samples. The first axis of the ordination separated the samples along a deer browsing intensity gradient. Sample scores decreased as length of time the plots were protected from deer browsing increased. Stem count data for species was regressed against sample scores. Species sensitive to deer browsing had significant negative correlations, whereas species that increased as browsing intensity increased had significant positive correlations. Forb diversity (H’) of protected and unprotected plots changed over time. Initially, the diversity of unprotected plots increased but then it declined as browse sensitive species increased in abundance, causing a decline in evenness (J). These results suggest that forb diversity may be enhanced by moderate to low levels of deer browsing.

Key words: browsing, Detrended Correspondence Analysis, diversity, Illinois, prairie forbs, whitetailed deer