PS 31-184 - Contrasting flammability of adjacent plant communities: Florida’s Apalachicola Bluffs and Ravines

Tuesday, August 9, 2011
Exhibit Hall 3, Austin Convention Center
John M. Mola1, J. Morgan Varner III2, Tova Spector3, Caroline Sullivan4 and Eamon A. Engber4, (1)Florida State University, Tallahassee, FL, (2)Forestry, Mississippi State University, Mississippi State, MS, (3)Florida Park Service, (4)Humboldt State University, Arcata, CA

Fire is a dominant disturbance that maintains diversity and heterogeneity. Plant species have developed a variety of adaptations to recurrent fires; among these is differential flammability of senesced litter. Plant communities of the southeastern United States experience a wide array of fire regimes, perhaps nowhere more marked than the juxtaposition of the fire-prone, xeric longleaf pine uplands bordering the mesic steephead ravines along Florida’s Apalachicola River. The ravines contain many endemic and disjunct species, notably the rare and endangered Torreya taxifolia.  Despite our wealth of knowledge regarding flammability of longleaf pine ecosystems, little is known about the relationship between the diverse ravines and fire. We collected leaf litter from 8 dominant ravine species to determine their flammability. Using standard laboratory flammability methods we burned litter from the eight most dominant tree species. 


We found differences among flame height, time and consumption (P<0.001). Comparisons of the 8 species found Torreya differed from all other groups in flame height (P<0.05), Torreya and Taxus floridana differed from all other species in flame time and fuel consumption (P<0.05). Torreya burned with the lowest flame heights (mean= 26cm). The flammability of the other ravine species (e.g., Fagus grandifolia and Liriodendron tulipifera) was comparable to those of pyric upland species (Pinus palustris and Quercus laevis). These results help inform the debate over the role of fire in the steephead ravines. While Torreya is now restricted to <3000 individuals, before the recent decline it was a dominant canopy species. The results of our study suggest that recent fire occurrences in the ravines may be anomalous and the increased presence of fire-facilitating species in the ravines may portend a shifting fire regime for these fire susceptible species. 

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