PARENT SESSION
Oral Session #55: Fire Ecology. Presiding: M. Moritz.
Wednesday, August 8, 2001. 1:00 PM to 5:00 PM. Hall of Ideas H.
Preserving restored tallgrass prairie using seasonal burning and mowing: Results from 1981-1993.
Bragg, Thomas1, Stubbendieck, James2, Butterfield, Charles3, 1 2 3
ABSTRACT- This study was initiated to assess long-term fire and mowing effects on species composition of a restored tallgrass prairie. In 1981, thirty-nine, 0.1 ha treatment-quadrats were established at a 4.5ha study site in eastern Nebraska. Treatments, replicated three times, included annual or quadrennial burn, mow, or hay with application in spring, summer, or fall. Plant community composition of each quadrat was evaluated in 1981, 1985, 1989, and 1993 by estimating species canopy cover within each of ten, 0.15m2 plots situated along a permanent, 21-meter transect. Smooth brome (Bromus inermis), a Eurasian, cool-season grass that invaded from roadside seedings, increased 7-35% with all but annual spring (-55%) and summer (-18%) burns. Big bluestem (Andropogon gerardii) increased 22% and 13% as smooth brome declined, changes mirrored by Indiangrass. Sideoats grama (Bouteloua curtipendula), a short-statured grass, decreased 4-27% as taller species dominated. Cover of sweet clover (Melilotus spp.), a biennial, Eurasian legume, varied significantly with highest values (+41%) occurring with annual summer and fall burns. Whorled milkweed (Asclepias verticillata), the principal native forb, increased throughout the study, particularly with annual burns (0-12%). Significant differences in species composition among treatments show the potential for management to affect unintended changes in species composition, including shifting from warm-season to cool-season dominated communities. Thus, careful selection of management type, season, and frequency are essential to ensuring that intended objectives of long-term tallgrass prairie management are accomplished.
KEY WORDS: tallgrass prairie, fire, mowing, diversity