Dynamics of balsam fir forests in relation to spruce budworm outbreaks in the Boreal Zone of Quebec

1994 ◽  
Vol 24 (4) ◽  
pp. 730-741 ◽  
Author(s):  
Hubert Morin
Keyword(s):  
Black Spruce ◽  
Growth Curves ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Boreal Zone ◽  
Growth Release ◽  
The North ◽  
Seedling Bank ◽  
Drastic Effect ◽  
Characteristic Growth

Age structures and growth curves were used to determine the origin and to follow the development of 17 balsam fir (Abiesbalsamea (L.) Mill.) stands in the middle of the Boreal Zone in the north of Lake Saint-Jean, Quebec. Every growth curve from the studied sites presented a more or less long period of suppression in the early growth of the balsam fir, followed by a marked release synchronous between the trees of a given site. Generally, a balsam fir cohort established just before the growth release. Characteristic growth releases generally occurred after the formation of exceptionally narrow rings, which took place around 1952, 1914, and between 1860 and 1890 in the sampled trees. Unimodal even-aged stands regenerated from balsam fir advanced growth following spruce budworm (Choristoneurafumiferana (Clem.)) outbreaks that rapidly defoliated the trees and caused openings, sometimes associated with blowdown; these outbreaks occurred between 1944 and 1953 (one stand), between 1909 and 1923 (six stands), and possibly between ca. 1860 and 1900 (seven stands). Bimodal and uneven-aged stands were associated with two spruce budworm outbreaks. In one stand, some of the trees regenerated from the spruce budworm outbreak that occurred between 1909 and 1923, but the 1944–1953 outbreak was intense enough to cause important defoliation and mortality, which released a second cohort. Finally, two stands regenerated from the possible spruce budworm outbreak that occurred around 1860–1900 and from the 1909–1923 outbreak. The presence of a fir cohort and associated growth release between 1860 and 1890 strongly suggests that an outbreak occurred at that time in the studied region. Every sampled stand from the Boreal Zone north of Lake Saint-Jean regenerated from a balsam fir seedling bank following a spruce budworm outbreak that affected the mature balsam fir canopy. These results are in good agreement with the hypothesis that spruce budworm outbreaks and balsam fir forests form an interdependent self-regulating system. Our study shows the drastic effect of spruce budworm outbreaks in the boreal forest, where black spruce (Piceamariana (Mill.) B.S.P.) dominates.

scholarly journals Sample Sizes Required To Estimate Defoliation of Spruce and Balsam Fir Caused by Spruce Budworm Accurately

1998 ◽  
Vol 15 (3) ◽  
pp. 135-140 ◽  
Author(s):  
David A. MacLean ◽  
Wayne E. MacKinnon
Keyword(s):  
Black Spruce ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Sample Sizes ◽  
Preliminary Assessment ◽  
Travel Costs ◽  
Host Trees ◽  
Sampling Protocols ◽  
Spruce Stands ◽  
Number Of Branches

Abstract Data from the assessment of current defoliation levels on 172,000 individual shoots from 6890 midcrown branches sampled from balsam fir and spruce stands were used to define sampling protocols for assessing defoliation caused by spruce budworm. The method was based on sampling one midcrown branch from each of x host trees per stand, and assessing defoliation of y individual shoots per branch. Both the number of shoots per branch and the number of branches required per stand varied with host species (balsam fir, white spruce, or red-black spruce) and with average defoliation level. Sample sizes required to estimate mean defoliation with 90% confidence that the confidence interval is ±10% ranged from 7 to 24 branches per stand and from 17 to 58 shoots per branch, with the largest samples required at moderate (31-70%) defoliation levels. Estimated costs of shoot and branch sampling and processing ranged from $40-110/stand, based on a 90% confidence level salary rate of $12(Can.)/hr, and excluding travel costs. Results can be applied using a preliminary assessment to determine the general defoliation level, which along with species, determines the required sample size. North. J. Appl. For. 15(3):135-140.

Black spruce decline triggered by spruce budworm at the southern limit of lichen woodland in eastern Canada

2001 ◽  
Vol 31 (12) ◽  
pp. 2160-2172 ◽  
Author(s):  
Martin Simard ◽  
Serge Payette
Keyword(s):  
Black Spruce ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
Jack Pine ◽  
Growth Patterns ◽  
Balsam Fir ◽  
Eastern Canada ◽  
Southern Limit ◽  
Epiphytic Lichen ◽  
Spruce Decline

Black spruce (Picea mariana (Mill.) BSP) is the dominant tree species of the southernmost (48°N) lichen woodlands in eastern Canada. Most spruce trees in mature lichen woodlands appear to be declining, as shown by the massive invasion of the epiphytic lichen Bryoria on dead branches of dying trees. A dendroecological study was undertaken to identify the main causal factors of the decline. A decline index based on the abundance of Bryoria on spruce trees was used to distinguish healthy from damaged lichen–spruce woodlands and to select sampling sites for tree-ring measurements. Three conifer species (black spruce, balsam fir (Abies balsamea (L.) Mill.), and jack pine (Pinus banksiana Lamb.)) were sampled to compare their growth patterns in time and space. In the late 1970s and mid-1980s, black spruce and balsam fir experienced sharp and synchronous radial-growth reductions, a high frequency of incomplete and missing rings, and mass mortality likely caused by spruce budworm (Choristoneura fumiferana (Clem.)) defoliation. Jack pine, a non-host species, showed no such trend. Because black spruce layers were spared, lichen woodlands will eventually regenerate unless fire occurs in the following years. Black spruce decline can thus be considered as a normal stage in the natural dynamics of the southern lichen woodlands.

Effets de la coupe à blanc et de la coupe par bandes sur la régénération obtenue après 5 ans dans des pessières noires du Québec

1995 ◽  
Vol 25 (2) ◽  
pp. 329-342 ◽  
Author(s):  
Pierre Pominville ◽  
Jean-Claude Ruel
Keyword(s):  
Black Spruce ◽  
Spruce Budworm ◽  
Lower Proportion ◽  
The Other ◽  
Balsam Fir ◽  
Clear Cutting ◽  
Other Hand ◽  
The One ◽  
Almost All ◽  
Coupe À Blanc

An experiment was conducted to compare the effects of traditional clear-cutting with those of strip cutting on regeneration of black spruce, Piceamariana (Mill.) B.S.P., stands on scarified and unscarified uplands and on lowlands. To that effect, regeneration surveys were done before cutting, in the following year, and 3 and 5 years after cutting. Five years after harvesting, strip cutting led to higher coniferous stocking than clear-cutting on scarified uplands and on lowlands. On unscarified uplands, the gain attributable to strip cutting was not significant. The coniferous stocking of strip cuts on scarified uplands was not greater than on unscarified uplands. So the efficiency of scarification could not be proved in that study. Stocking obtained after 5 years remained closely related to the one observed immediately after harvesting in the strip cufs as in the clear-cuttings. This is particularly true for balsam fir, Abiesbalsamea (L.) Mill. In the strip cuts, the balsam fir stocking was constant while the one of black spruce increased. This could have an impact on the evolution of the composition of the new stands and, consequently, on their vulnerability to spruce budworm, Choristoneurafumiferana (Clem.). The majority of the clear-cuttings were well regenerated 5 years after harvesting. Their average coniferous stocking was slightly above 60%. However, 48% of the clear-cuttings did not reach this level when only unscarified plots on uplands were considered. Advance growth was abundant in those plots but suffered high losses during harvesting. Consequently, reducing the losses during harvesting would result in a lower proportion of clear-cuttings with insufficient coniferous stocking 5 years after cutting. On the other hand, almost all the strip cuts with insufficient regeneration after harvesting were well regenerated 5 years later. Thus, strip cutting could be an interesting option on sites with insufficient advance growth and on sites well regenerated before cutting but where important losses during harvesting are anticipated.

Windthrow and growth response following a spruce budworm inspired, variable retention harvest in New Brunswick, Canada

2015 ◽  
Vol 45 (6) ◽  
pp. 659-666 ◽  
Author(s):  
Edward A. Wilson ◽  
David A. MacLean
Keyword(s):  
New Brunswick ◽  
Growth Response ◽  
Choristoneura Fumiferana ◽  
Abies Balsamea ◽  
Natural Disturbance ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Growth Release ◽  
Variable Retention ◽  
Variable Retention Harvest

Forest management regimes increasingly focus on the emulation of natural disturbance events, e.g., fire or insect outbreaks, to help increase ecosystem sustainability. We determined the residual stand response to a variable retention harvest inspired by spruce budworm (Choristoneura fumiferana (Clemens)) outbreaks in New Brunswick, Canada. Our objectives were to analyze the differences between surviving residual trees and those that succumbed to windthrow and to quantify growth release. The treatment was based on harvesting the estimated spruce budworm outbreak mortality, i.e., 90% of mature balsam fir (Abies balsamea (L.) Mill., 60% of mature spruce (Picea spp.), and no hardwoods. Windthrow increased with the proportion of trees harvested and averaged 52% over 7–9 years in these stands with high balsam fir – spruce content. One-third of 42 harvested plots sustained >30% windthrow, whereas 73% of 11 similar unharvested plots had <10% windthrow. Balsam fir had higher windthrow than spruce at 53% and 41%, respectively. Windthrown balsam fir trees had significantly larger diameters at breast height (DBH, 1.3 m), larger heights, and smaller crown ratios than surviving residual trees. Substantial growth release occurred, with DBH increment of residual trees 48%–64% greater than trees in unharvested plots. Balsam fir and intolerant hardwoods exhibited the largest growth response. We suggest that future spruce budworm inspired harvests in stands with high balsam fir – spruce content use two or three entries about 5 years apart to reduce windthrow.

scholarly journals Vulnerability of Conifer Regeneration to Spruce Budworm Outbreaks in the Eastern Canadian Boreal Forest

Forests ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 850 ◽  
Author(s):  
Janie Lavoie ◽  
Miguel Montoro Girona ◽  
Hubert Morin
Keyword(s):  
Boreal Forests ◽  
Black Spruce ◽  
Choristoneura Fumiferana ◽  
Management Strategies ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Insect Outbreaks ◽  
Spruce Stands ◽  
Canadian Boreal Forest

Spruce budworm (Choristoneura fumiferana) is the main defoliator of conifer trees in North American boreal forests, affecting extensive areas and causing marked losses of timber supplies. In 2017, spruce budworm affected more than 7 million ha of Eastern Canadian forest. Defoliation was particularly severe for black spruce (Picea mariana (Mill.) B.S.P.), one of the most important commercial trees in Canada. During the last decades, intensive forest exploitation practices have created vast stands of young balsam fir (Abies balsamea (L.) Mill.) and black spruce. Most research focused on the impacts of spruce budworm has been on mature stands; its effects on regeneration, however, have been neglected. This study evaluates the impacts of spruce budworm on the defoliation of conifer seedlings (black spruce and balsam fir) in clearcuts. We measured the cumulative and annual defoliation of seedlings within six clearcut black spruce stands in Quebec (Canada) that had experienced severe levels of defoliation due to spruce budworm. For all sampled seedlings, we recorded tree species, height class, and distance to the residual forest. Seedling height and species strongly influenced defoliation level. Small seedlings were less affected by spruce budworm activity. As well, cumulative defoliation for balsam fir was double that of black spruce (21% and 9%, respectively). Distance to residual stands had no significant effect on seedling defoliation. As insect outbreaks in boreal forests are expected to become more severe and frequent in the near future, our results are important for adapting forest management strategies to insect outbreaks in a context of climate change.

The influence of forest composition and climate on outbreak characteristics of the spruce budworm in eastern Canada

2013 ◽  
Vol 43 (12) ◽  
pp. 1181-1195 ◽  
Author(s):  
David R. Gray
Keyword(s):  
Black Spruce ◽  
Choristoneura Fumiferana ◽  
Basal Area ◽  
Spruce Budworm ◽  
Climate Scenario ◽  
Forest Composition ◽  
Eastern Canada ◽  
The North ◽  
Average Change ◽  
Maximum Temperatures

The spruce budworm (Choristoneura fumiferana Clemens) is perhaps the single most important disturbance agent in Canada’s eastern forests. Climate and forest composition are dominant factors in spruce budworm outbreak dynamics through their direct influences on the pest, its natural enemies, and its hosts, and through their influence on the multitrophic interactions that are important in outbreak dynamics. A combination of four climate variables, three forest composition variables, and one location variable explained 60% of the multivariate variability in outbreak characteristics (duration and severity) in eastern Canada. Outbreak duration was most strongly influenced by April–May accumulation of degree-days; outbreak severity was most strongly influenced by the extreme maximum temperatures of April–May. The basal area of balsam fir had a stronger influence than that of black spruce on duration and on severity. Both outbreak characteristics declined in more northerly locations. Under a projected future (2011–2040) climate scenario the largest increases in outbreak duration and severity are predicted to occur on the Gaspé Peninsula and the north shore of the St. Lawrence River (Quebec). The largest decreases in duration and severity are predicted to occur in southern Ontario and along the Bay of Fundy in New Brunswick and Nova Scotia. The predicted average change in outbreak duration is around –1.3 years. The predicted average change in outbreak severity is only slightly different from zero (around –1.5% defoliation).

EFFICACY OF FORAY 48B (BACILLUS THURINGIENSIS BERLINER) APPLICATIONS AGAINST THE SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (CLEMENS) (LEPIDOPTERA: TORTRICIDAE), TIMED FOR PHENOLOGICAL DEVELOPMENT OF BALSAM FIR AND BLACK SPRUCE

1993 ◽  
Vol 125 (3) ◽  
pp. 479-488 ◽  
Author(s):  
Beresford L. Cadogan ◽  
Roger D. Scharbach
Keyword(s):  
Bacillus Thuringiensis ◽  
Black Spruce ◽  
Choristoneura Fumiferana ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
Larval Survival ◽  
Balsam Fir ◽  
Early Instar ◽  
Respective Species ◽  
Respective Host

AbstractThe insecticide Foray 48B (Bacillus thuringiensis var. kurstaki Berliner) was applied undiluted at 30 BIU per ha to control spruce budworm, Choristoneura fumiferana (Clem.), in a mixed boreal forest stand of balsam fir, Abies balsamea (L.) Mill., and black spruce, Picea mariana (Mill.) B.S.P. When the treatment was timed to coincide with the early flushing of balsam fir shoots, the corrected budworm population reductions were 74 and 52% on balsam fir and black spruce, respectively. This treatment resulted in 19 and 8% defoliation on the two respective species. When the insecticide application was timed later to coincide with the late flushing of black spruce shoots the corrected population reductions were 93% on balsam fir and 72% on black spruce. Defoliation of the two species was 29 and 10% respectively, following this treatment. Larval survival on both species after the spray timed for black spruce (0.8 and 2.2 larvae per 45-cm branch on balsam fir and black spruce, respectively) was significantly less (P = 0.05) than that observed after the spray timed for balsam fir (4.6 and 4.2 larvae per 45-cm branch on the respective host species).The data indicate that the spray timed to correspond with the flushing of black spruce was generally more efficacious than the spray timed to impact on newly flushed balsam fir; nevertheless, the results raise the question as to how B. thuringiensis insecticides impact on early-instar budworm larvae when there is no preferred current year foliage on which the insects can feed.

Insect–host relationships influencing disturbance by the spruce budworm in a boreal mixedwood forest

2004 ◽  
Vol 34 (9) ◽  
pp. 1870-1882 ◽  
Author(s):  
V G Nealis ◽  
J Régnière
Keyword(s):  
Life Cycle ◽  
Populus Tremuloides ◽  
Black Spruce ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
White Spruce ◽  
Host Tree ◽  
Balsam Fir ◽  
Insect Host ◽  
Boreal Mixedwood Forest

Demographic data from a 15-year outbreak of the spruce budworm, Choristoneura fumiferana (Clem.) (Lepidoptera: Tortricidae), in a boreal mixedwood forest in Ontario, Canada, are used to interpret stand-level ecological disturbance in terms of susceptibility and vulnerability (mortality) of balsam fir (Abies balsamea (L.) Mill.), white spruce (Picea glauca (Moench) Voss), and black spruce (Picea mariana (Mill.) BSP). All three host-tree species are highly susceptible for oviposition by the spruce budworm and all are suitable for completion of the budworm life cycle. Host-related differences in susceptibility arise from the degree of synchrony between spruce budworm phenology during the feeding stages and host-tree phenology. Spruce budworm density was highest on white spruce throughout the budworm's life cycle and over the course of the outbreak, but more rapid flushing and growth of current-year buds in white spruce reduced damage relative to that on balsam fir. Conversely, later flushing of current-year buds on black spruce led to a reduction in budworm density early in the season and a corresponding reduction in defoliation. The combination of high budworm densities and severe defoliation caused mortality first on balsam fir. By the end of the outbreak, 89% of the balsam fir component >10 cm DBH was eliminated compared with 49% of the white spruce in the same size class. The lower susceptibility of black spruce resulted in survival of all but the smallest size classes of that species. Nonhost species such as trembling aspen (Populus tremuloides Michx.) nearly doubled their basal area during the outbreak. The results link processes inherent in the insect–host relationship with the population ecology of the insect and the disturbance ecology of the forest.

Fire return intervals and tree species succession in the North Shore region of eastern Quebec

2008 ◽  
Vol 38 (6) ◽  
pp. 1621-1633 ◽  
Author(s):  
Mathieu Bouchard ◽  
David Pothier ◽  
Sylvie Gauthier
Keyword(s):  
Tree Species ◽  
Forest Succession ◽  
Black Spruce ◽  
Abies Balsamea ◽  
Balsam Fir ◽  
Geographic Variations ◽  
Forest Patches ◽  
The North ◽  
Species Succession ◽  
South Axis

We evaluated geographic variations in mean fire return intervals and postfire forest succession within a 66 497 km2 land area located in the eastern Quebec boreal forest. Fire return intervals were calculated using a time since last fire map for 1800–2000, and forest dynamics were studied by superimposing 3204 forest inventory plots onto the fire map. Mean fire return interval proved significantly shorter in the western part of the study area, at 270 years, compared with the eastern part, where it was probably more than 500 years. The two main tree species in the study area were balsam fir ( Abies balsamea (L.) P. Mill.) and black spruce ( Picea mariana (Mill.) BSP). Balsam fir abundance increased progressively as a function of time since fire, whereas black spruce abundance increased during the first 90 years after fire and then declined. Balsam fir was significantly more abundant in the southeastern portion of the study area, which we attribute to the combined limitations imposed by temperature along the north–south axis and by fire along the east–west axis. Large forest patches (i.e., ≥200 km2) dominated by early successional tree species, within a matrix of irregular black spruce – balsam fir mixtures, are an important feature of preindustrial forest landscapes in this region.

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