Changing Fire Regimes and Their Implications for Vegetation Dynamics in the Appalachian Mountains

Authors: Charles W. Lafon*, Texas A & M University, Adam T. Naito, University of Arizona, Sally P. Horn, University of Tennessee, Thomas A. Waldrop, US Forest Service (retired)
Topics: Biogeography, Physical Geography
Keywords: disturbance history, fire history, fire suppression, pyrogeography, vegetation history
Session Type: Paper
Day: 4/4/2019
Start / End Time: 8:00 AM / 9:40 AM
Room: Regency Ballroom, Omni, West
Presentation File: No File Uploaded

The importance of fire in shaping Appalachian vegetation has become increasingly apparent over recent decades as fire-adapted species, including oak (Quercus) and pine (Pinus), have declined in abundance under the near-exclusion of fire. They are being replaced by fire-sensitive mesophytes. These changes imply that Appalachian vegetation developed under a history of burning before the fire-exclusion era, a possibility that has motivated investigations of Appalachian fire history using proxy evidence. Here we synthesize those investigations. Taken together, the proxy records portray frequent burning in the past. Fire-scar data from oak- and pine-dominated landscapes indicate that fires burned frequently, generally at intervals of less than 10 years, before exclusion. At study sites with long fire-scar records that cover multiple land use phases, fires generally burned at these high frequencies from before European settlement until the beginning of fire exclusion in the early- to mid-twentieth century, after which fire frequency declined sharply. These findings are supported by radiocarbon-dated soil and sediment charcoal, which indicates that fire has shaped Appalachian vegetation for many centuries to millennia. Dendroecological data on the age structure of xerophytic stands show that oak and pine species regenerated under the frequent burning of the past, while other species generally did not. However, fire exclusion has enabled maples (Acer) and other mesophytic species to expand from fire-sheltered sites onto dry slopes that formerly harbored pyrogenic vegetation, and has thereby diminished the topographic patterning of ecological communities.

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