Dendrochronogical reconstructions of western spruce budworm (Choristoneura occidentalis Freeman) at McCall Lakes, Peachland, British Columbia, Canada

ALFARO, RENE; AXELSON, JODI; LEWIS, KATHY; BARICHIVICH, JONATHON; DURAN, LARA; GEE, HUGO; HAAVIC, LAUREL; HARDY, KEVIN; JONES, EILEEN; LOPEZ, LIDIO; MANSILLA, CLAUDIA; PEÑA, MARIA PAZ; SUAREZ, MARIA LAURA

Las Vegas, USA

Congreso; 2009 AAG ANNUAL MEETING; 2009

Association of American Geographers

Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forest in the Southern Interior of British Columbia, Canada, have been known to have periodic defoliation due to western spruce budworm (WSB) (Choristoneura occidentalis Freeman) outbreaks.  Insect defoliators cause a reduction in annual growth during an outbreak and these reductions are visible in the tree-ring record.  In this study, we identify WSB outbreaks using dendrochronological methods.  We used increment cores from Douglas-fir growing in an area of known defoliation in the Peachland area of the Okanagan Forest District.  We used cores collected from ponderosa pine (Pinus ponderosa), a non-host species, to differentiate growth reductions caused by WSB outbreaks versus climatic effects (i.e., drought). We used the software program OUTBREAK to identify the timing, duration and magnitude of WSB outbreaks. We were able to identify eight distinct outbreak events in 202 years of record. Dendrochronological data was compared against the Forest Insect Disease Survey (FIDS), and to specific defoliation measurements taken at the site over eight year period.