Association of wildfire with tree health and numbers of pine bark beetles, reproduction weevils and their associates in Florida

Wildfires burned over 200,000 ha of forest lands in Florida froin 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 atnbrosia beetles, reproduction weevils and wood borers relative to lire severity. Over 27% of residual live trees in stands that experienced high fire severity died between October 1998 and May 1999. An additio~tal 2-3% of trees that initially survived the fire died during the second year compared to < I % mortality in unburned sta~ids. One year after the fire, Inore than 75% of the trees surviving in high fire severity stands had roots infected with one or more species of Lc>/~io,yr.~q?hi~tn~ andlor Grcrl,hi~lln spp. and nearly 60% of the sampled roots were infected. No such fungi were recovered from roots of trees ill unburned stands. Significantly, inore root weevils. Hvlo11iu.s /?trlc,.s and Pt1c.hy1obi~l.s pic~ovoru,~, were captured in ~tnbaited pitfalls in the moderate and liigh lire severity stands than in the controls. Mean trap catches of 1/1s ~ ~ ~ r t ~ t l i ( ~ ~ l l i . s . I > C I I L / ~ ~ ( . I ~ I I L I S P ~ < ~ ~ ~ . ( ~ I I . V anci Hyln.sr(,.r .sitl<~hr*).su.s, three cotnmon bark beetles that feed on phloern tissue of pines, were lower in 1.indgren traps in the fire-damaged areas than in the control stalids. In contrast, catches of the ninbrosia beetles, Xy1c.honr.s spp. and Moriar?hr-lrrrr n~clli, were higher in burned stands tha~i ll c(111tro1 statlds. The generalist predator, R~n~r~oc~lzilrr v r .st.c~ris (Coleoptera: Trogositidne), showed a strong positive relationship between abu~idance and lire severity, while the flat bark beetle. Si1vilnrr.v sp. (Coleoptera: Sylvanidae), exhibited the reverse trend. Our results show that most tree mortality occurred within I year of the lire. Ips or Dcr~cln)c~ori~c.s bark beetle populations did not build up in dead and weakened trees and attack healthy trees in 11earby areas. The prevalence of L~/?iogr-i~~~l~irrilz spp. in roots tnay be a sytnptoln of, or result in, weakened trees that may affect the trees' susceptibility to bark beetles in the fi~ture. ( ' 2002 Elsevier Science B.V. All rights reserved. K(~~it.or11.s: Wildfire: Scolytidae; Root dise;~sc: L,~~)ro,qnrl7l1i1rrir: l-' irlrs rlliotri: Pirlrr.~ pl~llrsrric