Monday, December 11, 2006 - 8:47 AM

Southern pine beetle, Dendroctonus frontalis and cut-and-leave suppression: Influencing forest stand dynamics through widespread mortality

Tom W. Coleman,, University of Kentucky, Department of Entomology, S 225 Agricultural North, Lexington, KY and Lynne Rieske,, University of Kentucky, Entomology, S-225 Ag North Building, Lexington, KY.

Widespread mortality from southern pine beetle (SPB), Dendroctonus frontalis, and associated cut-and-leave suppression continue to shape forest composition in the southeastern U.S. It is unclear how SPB-caused mortality, frequently implemented suppression techniques, and subsequent disturbance after SPB-caused mortality influence forest succession and future susceptibility to SPB outbreaks. My objective was to assess forest succession following extensive overstory mortality from SPB, cut-and-leave suppression, and the interaction of cut-and-leave and wildfire. I examined woody vegetation in loblolly pine, Pinus taeda, stands in wilderness areas of the Western Gulf Coastal Plain. Current vegetation composition and structure were modeled using the Forest Vegetation Simulator (FVS) to predict future canopy dominance 50 yr into the future. In east Texas, I compared succession after mortality from SPB and cut-and-leave to undisturbed loblolly pine stands. In Louisiana, cut-and-leave with subsequent wildfire was compared to stands with wildfire. Forest types predicted by FVS were analyzed using a Chi square (c2) analysis with Fischerís exact test. In Texas, modeling predicts that each SPB associated disturbance will significantly shift loblolly pine communities to hardwood-dominated stands relative to undisturbed stands (c2 df=2=7.06, P=0.04), and hardwood stands have low susceptibility to future SPB outbreaks. In Louisiana, modeling predicts that the occurrence of wildfire following each disturbance will sustain loblolly pine forest composition. However, these stands are predicted to perpetuate SPB outbreaks by promoting early-successional communities dominated by the favored loblolly pine. Hardwood vegetation appears to out-compete new pine regeneration and accelerate succession after dominant pine trees are killed by SPB associated events. Additional disturbance to understory species after canopy mortality appears to alleviate competition for shade-intolerant species, such as loblolly pine.

Species 1: Coleoptera Curculionidae Dendroctonus frontalis (southern pine beetle)

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