Dendrochronogical reconstructionsofwestern spruce budworm (Choristoneura occidentalis Freeman) atM cCall Lakes,Peachland,British Columbia,Canada

RENÉALFARO, JODI AXELSON, KATHYLEWIS, JONATHAN BARICHIVICH, LARA DURÁN, HUGO GEE, LAURELHAAVIK, KEVIN HARDY, EILEEN JONES , LIDIOLÓPEZ, CLAUDIA MANSILLA

Vancouver, Canada

Congreso; AmeriDendro; 2008

University of British Columbia,

Douglas-fir (Pseudotsugamenziesiii(Mirb.) Franco) forest in theSouthern Interior of BritishColumbia, Canada, havebeen known tohaveperiodicdefoliation duetowestern sprucebudworm (W SB) (Choristoneuraoccidentalis Freeman) outbreaks. Insect defoliators causea reduction in annualgrowthduring an outbreakandthesereductions arevisiblein thetree-ring record. In this study, weidentifyW SB outbreaks using dendrochronologicalmethods. W eusedincrement cores from Douglas-fir growing in an area ofknown defoliation in thePeachlandarea oftheOkanagan Forest District. W e usedcores colllectedfrom ponderosa pine(Pinus ponderosa), a non-host species, to diffferentiategrowthreductions causedbyW SB outbreaks versus climaticefffects (i.e., drought). W eusedthesoftwareprogram OUTBREAK toidentifythetiming, duration andmagnitudeofW SB outbreaks. W ewereabletoidentifyeight distinct outbreakevents in 202 years ofrecord. Dendrochronologicaldata was comparedagainst theForest Insect DiseaseSurvey(FIDS), andtospecificdefoliation measurements taken at thesiteover eight year period.