6B.2
Association of wildfire with long-term tree health and numbers of pine bark beetles and their associates in Florida
James Hanula, USDA Forest Service, Southern Research Station, Athens, GA; and J. Meeker, D. Miller, and E. Barnard
Wildfires burned over 200,000 ha of forest lands in Florida from April to July 1998. This unique disturbance event provided a valuable opportunity to study the interactions of summer wildfires with the activity of pine feeding insects and their associates in the southeastern United States. We compared tree mortality with abundance of bark and ambrosia beetles, reproduction weevils and wood borers relative to fire severity. Over 27% of residual live trees in stands that experienced high fire severity died between October 1998 and May 1999. An additional 2-3% of trees that initially survived the fire died during the second year compared to <1% mortality in unburned stands. One year after the fire, more than 75% of the trees surviving in high fire severity stands had roots infected with one or more species of Leptographium and/or Graphium spp. and nearly 60% of the sampled roots were infected. No such fungi were recovered from roots of trees in unburned stands. Despite the high levels of root injury almost no additional tree mortality has occurred since June 2000. More of root weevils were captured in unbaited pitfalls in the moderate and high fire severity stands than in the controls. Mean trap catches of three common bark beetles that feed on phloem tissue of pines were lower in Lindgren traps in the fire-damaged areas than in the control stands. In contrast, catches of ambrosia beetles were higher in burned stands than in control stands. Our results show that most tree mortality occurred within one year of the fire and was a result of fire injury. Ips or Dendroctonus bark beetle populations did not build up in dead and weakened trees and attack healthy trees in nearby areas. Long-term mortality resulting from root pathogen/bark beetle interactions did not occur. .
Session 6B, Fire Effects on Insects and Disease (TRACK II)
Thursday, 20 November 2003, 8:00 AM-9:30 AM
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