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Effects of stand and site characteristics on susceptibility and vulnerability of balsam fir and spruce to spruce budworm in New Brunswick

1997; NRC Research Press; Volume: 27; Issue: 11 Linguagem: Inglês

10.1139/x97-146

1208-6037

David A. MacLean, Wayne E. MacKinnon,

Rangeland and Wildlife Management

The relationships of spruce budworm (Choristoneura fumiferana (Clem.)) defoliation, and host tree growth and mortality, to soil drainage, tree species, budworm outbreak status (location), and productivity class were examined in 356 spruce (Picea sp.) n balsam fir (Abies balsamea (L.) Mill.) permanent sample plots in New Brunswick, Canada. Tree species, budworm outbreak status, and drainage class were significantly related to susceptibility to spruce budworm, which was quantified using defoliation levels from 1985 to 1988. On average, balsam fir sustained 6n9% more current and calculated cumulative defoliation than white spruce (Picea glauca (Moench) Voss) and 15n19% more than red (Picea rubens Sarg.) or black spruce (Picea mariana (Mill.) BSP). Moderate- to well-drained sites sustained 7n17% more current and 5n7% more cumulative defoliation than imperfectly or poorly drained sites. When pooled for species, rich sites sustained significantly higher cumulative defoliation than poor or medium sites. Soil drainage showed significant main and defoliation × drainage interaction effects on both mortality and net basal area change. However, within stand types, drainage effects were significant only for white spruce under light defoliation and sprucenfir under moderate defoliation, with no significant differences occurring for balsam fir, red spruce, black spruce, or firnspruce stand types. Therefore, we support the recommendation of Y. Bergeron, A. Leduc, H. Morin, and C. Joyal (1995. Balsam fir mortality following the last spruce budworm outbreak in northwestern Quebec. Can. J. For. Res. 25: 1375n1384) that the emphasis put on soil drainage class and surficial deposit as predictors of stand vulnerability to budworm should be reevaluated. Resume : La relation entre diune part la dOfoliation par la tordeuse des bourgeons de liOpinette (Choristoneura fumiferana (Clem.)), la croissance et la mortalitO de liarbre hUte, et diautre part le drainage, liespce diarbre, liOtat de liOpidOmie de tordeuse (localisation) et la classe de productivitO a OtO examinOe dans 356 placettes diOchantillonnage permanentes contenant de liOpinette (Picea sp.) et du sapin baumier (Abies balsamea (L.) Mill.) et situOes au Nouveau-Brunswick, Canada. Liespce diarbre, liOtat de liOpidOmie de tordeuse et la classe de drainage Otaient significativement reliOs ‡ la vulnOrabilitO ‡ la tordeuse des bourgeons de liOpinette qui a OtO quantifiOe ‡ liaide des niveaux de dOfoliation de 1985 ‡ 1988. En moyenne, le sapin baumier subissait 6n9% plus de dOfoliation courante et cumulative calculOe que liOpinette blanche (Picea glauca (Moench) Voss) et 15n19% plus que liOpinette rouge (Picea rubens Sarg.) ou que liOpinette noire (Picea mariana (Mill.) BSP). Les sites avec un drainage de modOrO ‡ bon subissaient 7n17% plus de dOfoliation courante et 5n7% plus de dOfoliation cumulative que les sites ‡ drainage imparfait ou pauvre. Lorsquiils Otaient regroupOs en fonction des espces, les sites riches subissaient une dOfoliation cumulative significativement plus forte que les sites pauvres ou moyens. Le drainage seul et en interaction avec la dOfoliation avait des effets sur la variation dans la mortalitO et la surface terrire. Cependant, ‡ liintOrieur des types de peuplements, les effets du drainage Otaient significatifs seulement dans le cas de liOpinette blanche avec une dOfoliation lOgre et de celui des peuplements diOpinettensapin avec une dOfoliation modOrOe. Il niy avait pas de diffOrence significative dans le cas des peuplements de sapin baumier, diOpinette rouge, diOpinette noire et de sapinnOpinette. Par consOquent, nous appuyons la recommandation de Y. Bergeron, A. Leduc, H. Morin et C. Joyal (1995. Balsam fir mortality following the last spruce budworm outbreak in northwestern Quebec. Can. J. For. Res. 25 : 1375n1384) qui suggOrait de rOOvaluer liimportance accordOe ‡ la classe de drainage et aux dOpUts de surface comme facteurs de prOdiction de la vulnOrabilitO des peuplements ‡ la tordeuse. (Traduit par la ROdaction)