Impacts of Repeated Wildfire on Vegetation in the Southern Appalachian Mountains

Authors

Thomas A. Waldrop, U.S. Forest Service
Donald L. Hagan, Clemson University
Matthew Reilly, University of Oregon

Date of this Version

2013

Document Type

Article

Citation

JFSP Project ID: 09-1-10-1

Comments

US government work.

Abstract

The infrequent occurrence of large wildfires in the southern Appalachian Mountains over the last several decades has offered few opportunities to study the impacts of these types of disturbances. As a result, relatively little is known about how heterogeneity in topography, vegetation, and recent disturbance history interact to influence patterns of fire severity across the landscape. Since 2000, five separate wildfires burned a large portion of the area in, and surrounding the Linville Gorge Wilderness in western North Carolina, two burned the same area a second time. Burn severity and vegetative recovery were measured in 152 plots established in 1992 prior to any wildfires. Field measurements of severity were strongly related to GIS data, allowing an accurate map of severity conditions in all 5 burned landscapes. Severity followed similar patterns at all fires. The most severely-burned areas were on the higher elevations, probably ridges, on slopes of moderate steepness, and facing to the south, southwest, west, or northwest. The effects of 1 burn vs. 2 burns were more pronounced in dry-site than in moist-site communities. Shrub and tree cover decreased at all levels of re-burn severity. Herb richness and total richness were highest in the highest level of re-burn severity. Significant changes (increases) in species richness occurred only at scales < 1 m2, which is likely a reflection of large-scale community heterogeneity and/or heterogeneous patterns of burn severity. Woody plant community assembly was not substantially affected by burning, nor did burning appear to promote exotic plant invasion. Our measurements and maps of fire severity will help managers to better understand vegetative response to wildfire across widely diverse topographic and severity conditions.