PARENT SESSION
Poster Session #6: Conservation Ecology.
Monday, August 6, 2001. Presentation from 3:30 PM to 5:00 PM. Exhibition Hall
Erosion of plant diversity in prairie remnants slowed but not stopped by recent fires.
Milbauer, Michelle1, Leach, Mark2, 1 2
ABSTRACT- The once-extensive prairies of Wisconsin are now represented by small, isolated remnants. A previous re-census of 54 remnants revealed alarming losses of vascular-plant diversity over a 32- to 52- year period. Our study refines that study by comparing diversity at a finer scale (1-m2, rather than site presence) and by considering fire history. We resampled 21 remnants that had been similarly sampled in the 1940s and 1950s. We learned each site's fire history: Twelve had burned at least once in the previous five years ("burned"); nine had not burned within 10 years ("unburned"). Considering all species, 
-diversity (number of species/m2) increased in burned (mean = 2.8 ± 3.3 S.D.) and unburned sites (mean = 1.3 ± 3.7). Mean -diversity of native species increased slightly in burned sites (mean = 0.11 ± 3.2) and decreased in unburned sites (mean = −2.0 ± 3.7). However, fire's apparent maintenance of native diversity is deceptive. Native species previously reported to have low fidelity to remnant vegetation increased in -diversity in burned (mean = 0.97) and unburned (mean = 1.1) sites, while mid and high fidelity native species decreased in both burned (mean = −0.15 and −0.90, respectively) and unburned (mean = −0.76 and −2.5, respectively). Only two managed sites showed increases in -diversity of high-fidelity species. Recent fire management is not halting the erosion of species of the most conservation concern.
KEY WORDS: prairie, fire, diversity, Wisconsin