Effects of Spruce Budworm on Cone Production by Balsam Fir

Dynamique d'ktablissement d'un peuplement bi4tagk de bouleau blanc et de sapin baumier en zone borkale par Louis BPlanger, Daniel ~l l a r d ' et Philippe MeekThe age structure of a boreal two-storied stand formed by an La structure d'8ge d'un peuplement bortal bi-CtagC constituC upperstory of white birch (Betula papyrifera Marsh.) with an d'une strate arborescente de bouleau blanc (Betula papyrifera understory of balsam fir (Abies balsamea (L.) Mill.) was Marsh.) et d'un sous-Ctage arbustif de sapin baumier (Abies balanalysed. The establishment of this 50-year stand followed a samea (L.) Mill.) a Ct C CtudiCe. Ce peuplement a pour origine bum that ran through a cut-over area. The objective was to verify un feu datant d'une cinquantaine d'annCes survenu aprbs la if the establishment of the fir understory followed the traditional rCcolte des sapinibres dans ce secteur. Le but de 1'Ctude Ctait succession model or the initial floristic composition model. The de verifier si la dynamique d'ktablissement du sapin suivait age structure analysis indicated an immediate and rapid establ'hypothese classique de la succession ou le modble de la comlishment of white birch during a period of 6 years after the fire. position floristique initiale. Les structures d'bge obtenues indiEstablishment of fir, however, was initiated only 16 years after quent que le bouleau s'est Ctabli au cours des six premibres the fire. Peak establishment was 33 years after the fire. Fir annCes qui ont suivi le feu. Le sapin, par contre, a pris 16 ans regeneration followed a cycle. The regeneration pattern was avant de commencer B s'8ablir. Son pic d'ktablissement se situe characterized by the absence of fir establishment the first 16 years 33 ans aprbs le feu. L'installation du sapin a suivi un patron after the fire, followed by sporadic fir regeneration the next qui se rapproche d'une normale. Ce patron est caractCrisC par 12 years, then by a 13-year period of abundant regeneration after l'absence d'ktablissement de sapin les premiers 16 ans, une phase which there was a complete halt to fir regeneration. So, in this d'installation sporadique les 12 annCes suivantes, une phase case, the successional model was more fit to describe the d'installation abondante d'environ 13 ans suivie d'une dernibre dynamics of balsam fir. The absence of fir regeneration during phase oh I'Ctablissement du sapin s'est compktement interrompu. the initial period after the fire could be explained by the absence Donc, dans cette Ctude de cas, la dynamique du sapin est mieux of the nearby fir seed sources due to harvesting. However, the dCcrite par un modble de succession. La longue pCriode ayant total absence of fir establishment during the last period is more prCcCdC 1'Ctablissement du sapin est like possiblement B l'absence difficult to explain. Seedbed evolution since the fire could posde semenciers alors que les sapinibres mares venaient tout juste sibly be in cause. This and other studies indicate that in the boreal d'gtre rCcoltCes. Par contre, l'interruption observCe ...

Section: Rcsultatsunclassified

Dynamique d'établissement d'un peuplement bi-étagé de bouleau blanc et de sapin baumier en zone boréale

Bélanger¹,

Allard²,

Meek³

1993

“…Meades (1984) a observC une bonne rCgCnCration sous couvert de sapin, m&me lorsque la mortalitC approchait 100 %. Une bonne proportion de cette rCgCnCration Ctait probablement prCsente au dCbut de 1'Cpidtmie puisque la production de semences cesse habituellement aprks quelques annCes de difoliation (Fye et Thomas 1963;Powell 1973;Schooley 1978;Meades et Schooley 1981). Ceci explique que plusieurs auteurs aient observe un plus faible Ctablissement de semis de sapin en pCriode CpidCmique (Ghent et al 1957;Osawa 1986;C6tC et BClanger 1991).…”

Section: Rcsultats Et Discussionunclassified

“…Les dommages ont Ct C considCrCs comme lCgers lorsque la mortalit6 de mCme que la defoliation moyenne Ctaient infkrieures B 25 7%. 11s ont Ct C classes c o m e modirks lorsque la mortalit6 demeurait inferieure B 25 % mais que (MacLean 1984, Schooley 1978. L'analyse a ainsi d0 tenir compte de la progression regionale de I'CpidCmie.…”

Section: M6thodologieunclassified

“…Dans des cas sCvbres toutefois, l'infestation pourrait dktruire la rCgCnCration prCB tablie et arrCter la production de semences de sorte que les superficies dtvastCes risquent d'Ctre envahies par des arbustes et des essences de faible valeur commerciale (Ghent et al 1957;Fye et Thomas 1963;Hatcher 1964;Mott 1974;Potvin 1980;Munro 1981;Fowle 1983;Batzer et Popp 1985). La diminution des structures de reproduction pourrait s'accentuer avec la sCvCritC et la durCe de 1'CpidCmie (Powell 1973;Schooley 1978). Meades et Schooley (198 1) croient ainsi que, sur les stations fertiles, la proportion de feuillus et en particulier celle du bouleau B papier aura tendance B augmenter chaque fois qu'un peuplement sera endommagi par la tordeuse.…”

Section: Introductionunclassified

See 1 more Smart Citation

Impact de la tordeuse des bourgeons de l'épinette [Choristoneura fumiferana (Clem.)] sur la régénération des sapinières après la coupe à blanc

Ruel¹,

Huot²

1993

Impact de la tordeuse des bourgeons de l'kpinetteMill.] stands has shown some effects of spruce budworm entre les dommages causCs par la tordeuse des bourgeons de defoliation on regeneration after clearcutting. Even though soft-1'Cpinette et la rCgCnCration de ces peuplements aprbs coupe.wood stocking was consistently high prior to harvesting operaBien que le coefficient de distribution des rksineux avant la coupe tions, longer infestation periods or more severe defoliation levels varie peu avec le niveau de dommages, des dommages plus led to a decrease in the stocking of softwood stems above 50 cm sCvbres ou survenant sur une pCriode prolongCe ont pour effet height and to the establishment and development of hardwood de diminuer la prCsence des semis de hauteur sugrieure B 50 cm advance growth. Hardwoods were more often in a dominant posiet de favoriser l'implantation et le dCveloppement d'une rCgCtion in the most severely damaged stands and the budworm effect nCration feuillue en sous-Ctage. Cinq ans aprbs la coupe, cet effet was still persistent on the regeneration structure even 5 years sur la rCgCnCration pr6Ctablie est toujours perceptible sur la strucafter logging. Cutovers with less than 60% stocking were also ture de la rtgCnCration, les feuillus occupant plus frCquemment more frequent in the most severely devastated fir stands. This une position dominante dans les peuplements les plus touchCs.situation seemed directly related to the impact of the spruce De plus, les superficies prCsentant des coefficients de distribubudworm on balsam fir advance growth. tion de moins de 60 %, cinq ans aprbs coupe, sont plus abondantes dans ces peuplements et ceci semble directement attriKey words: balsam fir, Choristoneura fumiferana, advance buable B l'effet de l'insecte sur la rCgCnCration prCCtablie.growth, clearcuttingMots clCs: sapin baumier, Choristoneura fumiferana, rCgCnCration prCCtablie, coupe B blanc IntroductionLa dynamique des peuplements bortaux a fait jusqu'h maintenant l'objet de nombreuses recherches. La notion classique de climax, en particulier, a suscitt de strieuses discussions car, bien qu'elle tende vers un stade final, la succession forestikre est souvent interrompue par une perturbation naturelle comme le feu, le chablis ou les Cpidtmies d'insectes (Larsen 1980). Ceci est particulikrement vrai dans les sapinikres qui sont soumises de f a~o n cyclique aux attaques de la tordeuse des bourgeons de 1'Cpinette (Baskerville 1975, MacLean 1984, Lortie 1979.Le dynamisme nature1 des forCts en l'absence de feux permet au sapin de s'installer sur des stations trks variCes. I1 peut s'installer avec agressivitC sous divers peuplements mCme lorsque son importance par rapport B la surface terrikre totale est de moins de 40 % (Ghent et al. 1957). Le sapin s'installe aussi de f a~o n naturelle sous certaines forCts surannCes oh le couvert est interrompu par la dittrioration naturelle du peuplement (Baskerville 1965;Boivin 1978) Des perturbations anthropogCniques comme la coupe partielle dans certains peuplemen...

“…No dlfferences between the two appl~cat~on rates of each of the ~nsect~cides could be detected by means of the t-test for per cent cones damaged by any of the Insects for the three lnsecticldes In either plantat~on Hence, data for the two concentratlons are comb~ned for comparison of the effects of ~nsect~c~des on each Insect by one-way analys~s of varlance (Table 1 ) The rncldence of cones damaged by spruce budworm was very low (0 to 5%) In the 12-year-old plantatlon and none was damaged In the older plantat~on; no reductions due to lnsectlclde treatments could be detected Damage by spruce coneworm was 20% for untreated trees rn the 12-yearold plantation and all lnsectrclde treatments slgnlflcantly reduced cone damage by t h~s Insect No dlfferences in effectlveness of lnsectlcldes were evldent In the25-year-old plantatlon damage was low and no reductlons due to treatments were observed Young larvae of spruce budworm and coneworm that emerge from hlbernacula feed by mlnlng In needles and buds over the whole crown prlor to budbreak As they mature, they feed on new shoots, male and female stroblll, and developing cones, so that stroblll are glrdled or destroyed at the flowerlng stage by the budworm (Powell 1973, Schooley 1978) and the coneworm (McLeod and Davlault 1963) Each of the chemlcals tested has been found effectlve for control of late-lnstar budworm larvae wlth mlstblower appllcatlons of d~lute solutions on whlte spruce trees Campbell 1972, 1974), but there IS no evldence that second-lnstar larvae can be effectlvely controlled by such treatment To control early larvae that glrdle or destroy strob111 at the flowerlng stage, hydraullc spraylng before flowerlng may be requlred Hydrau-IIC sprays of acephate applled to budworm-lnfested Douglasflr (Pseudotsuga rnenz~esll (Mlrb ) Franco) trees at the needleand bud-mlnlng stage provlded effective control of larvae lnslde needles and buds, but d~d not reduce externally vlslble damage to buds (Brewer and O'Neal 1977) It remains to be shown whether or not buds and flowers on whlte spruce can be protected Early treatments mlght also provlde protectlon from coneworm as ~t IS slmllar to budworm In phenology and feedlng hablts (McLeod and Davlault 1963) As these lnsects are not conflned to the cone-bearlng portlon of the crown, the whole tree may have to be sprayed to achleve effectlve control unless chem~cals are effectlvely translocated wlthln the tree Moreover, all trees wlthln an orchard will require spraylng because these Insects will not be conflned to cone-bearlng trees There was no damage by spruce seedmoth In trees of the young plantatlon In the older plantatlon, 21% of cones from untreated trees were damaged. Slgnlflcant reductlons In damage were found on trees treated w~th dlmethoate and methomyl but not on those treated wlth acephate Spruce cone maggot was the most damaglng Insect In control trees of both plantatlons -49% In the younger and 47% In the older one Damage was slgnlflcantly reduced In both plantatlons by each lnsectlclde lncldence of spruce cone-axis mldge damage In control trees was 38 and 14O/0 respectively In the older and younger plantatlon In the younger plantatlon each Insectlclde slgnlflcantly reduced damage, whereas In the older plantatlon only dlmethoate and methomyl were effectlve The seedmoth, cone maggot, and cone-axls mldge OVIposlt durlng or after the peak of flowerlng, and larvae feed exclus~vely wlthln cones Slnce the proportlon of the tree that bears cones w~ll vary among crop years (EIS and Inkster 1972) and posslbly among trees wlth...…”

Section: Resultsmentioning

confidence: 99%

A Test of Foliar-applied Systemic Insecticides to Prevent Damage to White Spruce Cones by Insects

Fogal¹,

Lopushanski²

1985

Cone-bearing portions of white spruce trees were sprayed by means of hydraulic sprayers with 1.0 and 1.5 per cent solutions of dimethoate, methomyl, and acephate in a 12-year-old and a 25-year-old plantation. Cone damage was reduced by insecticides but no differences between the two application rates were detected. In the younger plantation, each insecticide provided highly significant reductions in damage by spruce coneworm, spiral spruce cone maggot, and spruce cone-axis midge, but neither reduced spruce budworm damage; there were no differences among insecticides. In the older plantation, each insecticide provided significant and equal reductions in cone maggot damage; seedmoth and cone-axis midge damage was reduced by dimethoate and methomyl, but not acephate, and no insecticide reduced coneworm damage. Some factors to consider in further testing of these or other insecticides for use against cone-damaging insects on seed trees are discussed.