ANDERSON, ROGER C.1*, NELSON DEBRA1,2, and MARCIA A. RICKEY1. 14120 Department of Biological Sciences, Illinois State University, Normal, IL 61790-4120 USA; 2Illinois Department of Natural Resources, 110 James Rd., Spring Grove, IL 60081 USA. - Response of prairie forbs to whitetailed deer browsing.
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.