Influence of Fire and Southern Pine Beetle on Pine-Dominated Forests in The Linville Gorge Wilderness, North Carolina

Abstract

Historically, fire and the southern pine beetle (Dendroctonus frontalis) have interacted in a manner that maintains the stability of pine-dominated forests in the southern Appalachians. Fire suppression has recently been implicated in the disruption of the integrity of these forests and their shift toward hardwood dominance. This study examined the influences of fire and southern pine beetle infestation on stand structure and resin flow of pines in pine-dominated forests in the Linville Gorge Wilderness of North Carolina. Resin flow in most pine species increases in response to various types of wounding and is a pine tree's primary defense against insect pathogens. Pine-dominated stands in this study decreased in both basal area and density after exposure to fire and/or southern pine beetle infestation. Decreases in basal area and density of Pinus pungens were strongly associated with infestation, while decreases in Pinus rigida were influenced primarily by exposure to fire. Resin flow was substantially higher in trees that were exposed to fire, but not infested, than in trees experiencing any other combination of fire exposure and infestation (including trees that were neither exposed to fire nor infested). This elevated resin flow was still present 18 mo after burning. Since resin flow is the primary means of host defense against southern pine beetle, it is suspected that fire could confer an acquired resistance to future southern pine beetle infestations through elevated resin flow.