Canadian Forest Service Publications
The influence of forest and stand conditions on spruce budworm defoliation in New Brunswick, Canada. 2003. MacKinnon, W.E.; MacLean, D.A. Forest Science 49: 657-667.
Issued by: Atlantic Forestry Centre
Catalog ID: 23124
CFS Availability: PDF (request by e-mail)
The species composition of stands and surrounding forest have been suggested as important factors influencing the amount of spruce budworm (Choristoneura fumiferana (Clem.)) defoliation and, consequently, budworm-induced growth loss and mortality. We measured spruce budworm defoliation from 1989-1993 in 40 spruce (Picea sp.) and balsam fir (Abies balsamea (L.) Mill.) stands in north-central New Brunswick, Canada, and evaluated the influence of surrounding forest type (softwood, mixedwood), species group (balsam fir, spruce, and site quality (wet/nutrient poor, moist/nutrient rich) on defoliation. Surrounding forest type had a significant effect on the amount of defoliation in white spruce (Picea glauca (Moench) Voss) stands; stands in softwood forests sustained 11% more (P = 0.0485) defoliation than those in mixedwood. There was evidence that hardwood species have to be within, rather than surrounding, a spruce-fir stand to significantly influence defoliation. Site quality had a significant effect (P = 0.0039) on balsam fir defoliation, with stands on moist/rich sites sustaining 19% more defoliation than those on wet/poor sites. In softwood forest, white spruce stands sustained an average of 16% more defoliation than red-black spruce (Picea rubens Sarg. - Picea mariana (Mill.) B.S.P.) stands.