Conservation Biology of Eastern Tallgrass Prairie: Integrating Issues of Management and Restoration for the 21st Century
Bowles, Marlin , Jones, Michael .
How Often Should Eastern Tallgrass Prairies Burn? Fire Frequency and Long-term Changes in Plant Species Richness, Composition and Vegetation Structure.
Little information has been available from large data sets on effects of fire on long-term change in eastern tallgrass prairie. Work on western tallgrass prairie indicates that although periodic fire maintains species richness, it declines with increasing fire frequency and grass cover without grazing disturbance. We examined 25-year changes in species richness, composition and structure in 38 currently ungrazed Chicago region prairies with known fire management histories. About half of the sites appear to have been lightly disturbed some time prior to initial data collection. Change over time in mean plot species richness correlated positively with increasing fire frequency, with 20 percent fire frequency projected to prevent loss of richness in mesic/wet mesic prairies and 10 percent needed to stabilize dry/dry-mesic prairies. Composition of undisturbed late-successional prairies, as measured by percent similarity over time, stabilized with 50 percent fire frequency, while disturbed prairies did not stabilize, presumably due to successional change enhanced by fire. Change in structure measured by the ratio of woody/graminoid species abundance increased with decreasing fire frequency in mesic/wet-mesic prairies, with 65 percent fire frequency projected to prevent change in this ratio. This relationship did not hold for dry/dry-mesic prairies, possibly due to lower rates of accumulation of woody vegetation and litter. However, in all habitats there was a negative correlation between change in forb species richness and increase in the woody/graminoid ratio. These results suggest that for ungrazed eastern tallgrass prairie, 1) more frequent burning is needed to stabilize composition and structure than species richness, 2) less frequent burning is needed for dry/dry-mesic than for mesic/wet mesic habitats and 3) increasing fire frequencies do not result in loss of species richness.
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1 - The Morton Arboretum, 4100 Illinois Route 53, Lisle, Illinois, 60532, USA
2 - Christopher Burke Engineering, Rosemont, IL., 60018, USA
Presentation Type: Symposium or Colloquium Presentation
Location: Williford B/Hilton
Date: Wednesday, July 11th, 2007
Time: 8:45 AM