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.

Year: 2003

Available from: Atlantic Forestry Centre

Catalog ID: 23124

Language: English

CFS Availability: Order paper copy (free)


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.

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