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Vincent G. Nealis - One of the best experts on this subject based on the ideXlab platform.
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Density Dependence of Egg Recruitment and Moth Dispersal in Spruce Budworms
Forests, 2019Co-Authors: Jacques Régnière, Vincent G. NealisAbstract:Egg recruitment quantifies the relative importance of realized fecundity and migration rates in the population dynamics of highly mobile insects. We develop here a formal context upon which to base the measurement and interpretation of egg recruitment in population dynamics of eastern and western spruce Budworms, two geographically separated species that share a very similar ecology. Under most circumstances, per capita egg recruitment rates in these Budworms are higher in low-density populations and lower in high-density populations, relative to the regional mean: Low-density populations are nearly always migration sinks for gravid moths, and dense populations nearly always sources. The slope of this relationship, measured on a log scale, is negatively correlated with migration rate, and ranges between 0 and −1. The steeper the slope, the more marked net migration. Using our western spruce Budworm observations, we found strong evidence of density-dependent emigration in Budworms, so migration is not simply a random perturbation in the lagged, density-dependent stochastic process leading to Budworm outbreaks. It is itself statistically and biologically density-dependent. Therefore, moth migration is a synchronizing factor and a spread mechanism that is essential to understanding the development and expansion of spruce Budworm outbreaks at regional scales in the boreal forests of North America.
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Why western spruce Budworms travel so far for the winter
Ecological Entomology, 2016Co-Authors: Vincent G. Nealis, Jacques RégnièreAbstract:1. Conifer-feeding Budworms (Choristoneura) hibernate in sheltered locations on their host trees from late summer of 1 year to spring of the next. During this period, they do not feed but rely on sustenance provided in the egg. Overwinter survival is dependent on the rate of consumption of these limited reserves. 2. A process model was developed that quantifies the relationship between the rate of consumption and survival at variable temperatures and exposure times for western spruce Budworm. The model supported physiological evidence that warm weather conditions early in the diapause period have a dominant influence on overwinter survival. Output compared favourably with field observations of poorer Budworm survival at lower elevations where late-summer and autumn temperatures were warmer compared to those overwintering at cooler, higher elevations. 3. Field experiments demonstrated these weather-dependent rates of survival were modulated significantly by the degree of shelter experienced by hibernating Budworms. 4. Dissection of whole trees harbouring overwintering western spruce Budworms showed a significant portion of the population had travelled a considerable distance from the periphery of the tree canopy where eggs were laid to overwinter successfully on the tree bole where sheltered niches are common. 5. Thus, Budworms will travel relatively long distances and risk increased mortality during this dispersal to find adequate shelter to overwinter.
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Balancing risks of disturbance from mountain pine beetle and western spruce Budworm
Canadian Journal of Forest Research, 2009Co-Authors: Vincent G. Nealis, M. K. Noseworthy, R. Turnquist, V. R. WaringAbstract:The effect of removing lodgepole pine (Pinus contorta Dougl. ex Loud.) and retaining Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) to reduce the risk of disturbance from mountain pine beetle (Dendroctonus ponderosae Hopk.) in mixed conifer stands in southern British Columbia, Canada, on population processes influencing outbreaks of western spruce Budworm (Choristoneura occidentalis Free.) was evaluated in 10 paired (open vs. closed) field plots. Overall feeding damage to Douglas-fir was significantly, but only slightly, lower in open stands compared with closed stands. Although open plots tended to recruit more Budworms, the losses resulting from the dispersal of spring-emerging Budworms in search of feeding sites were significantly greater in open plots. The forest management benefits of these early season losses were mitigated, however, by more mortality of Budworms from natural enemies, particularly diseases, in the closed plots during the Budworm feeding period. These results are discussed in ter...
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Risk of Dispersal in Western Spruce Budworm
Agricultural and Forest Entomology, 2009Co-Authors: Vincent G. Nealis, Jacques RégnièreAbstract:1 Western spruce Budworm Choristoneura occidentalis Free. larvae emerge in the spring before buds have expanded and spend a variable period of time foraging on branches and mining needles. 2 Losses of dispersing Budworms during this needle-mining period are related directly to the severity of defoliation in previous years and inversely related to foliage biomass in the study plot and to temperature and rainfall during the needle-mining period. 3 Losses can be interpreted in terms of risk of dispersal, which is the product of the propensity of early-stage Budworms to disperse in search of resources and the consequences of this behaviour for survival under variable ecological conditions. 4 A comparison of the species-specific nature of risk of dispersal in three conifer-feeding Budworm systems of North America may elucidate the common nature but variable features of their respective population dynamics.
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Seasonal Changes in Foliar Terpenes Indicate Suitability Of Douglas-fir Buds for Western Spruce Budworm
Journal of Chemical Ecology, 2005Co-Authors: Vincent G. Nealis, Jason R. NaultAbstract:The terpene composition of current-year buds of Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, was analyzed from before budburst to after buds were fully flushed. Terpene composition was measured at weekly intervals for several seasons at eight different locations in the southern interior of British Columbia, Canada. Discriminant functions relating terpene composition to suitability of buds for newly emerged western spruce Budworm, Choristoneura occidentalis Freeman, were developed based on terpene profiles of the buds and bioassays measuring the suitability to Budworms of a sister group of buds. Changes in percent composition of bud terpenes before and during budburst were closely associated with changes in the suitability of the buds to utilization by Budworms at both the tree and site by date levels. Use of a degree-day scale for bud suitability removed much of the year-to-year variation, but remaining differences among sites suggest additional sources of variation influencing the insect-host plant relationship. The success of correctly classifying bud suitability using terpene profiles demonstrates the value of foliar terpenes as indicators of seasonal changes in suitability of Douglas-fir foliage during the critical spring emergence period of western spruce Budworm. This indicator could be used to screen individual trees susceptible to Budworm damage and identify sites at high risk of damaging defoliation.
Karen M. Clancy - One of the best experts on this subject based on the ideXlab platform.
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The Role of Monoterpenes in Resistance of Douglas Fir to Western Spruce Budworm Defoliation
Journal of Chemical Ecology, 2002Co-Authors: Zhong Chen, Thomas E. Kolb, Karen M. ClancyAbstract:We conducted defoliation experiments with 7- to 8-year-old clones of Douglas fir [ Pseudotsuga menziesii (Mirb.) Franco var. glauca ] to assess the role of monoterpenes as a resistance mechanism to western spruce Budworm ( Choristoneura occidentalis Freeman) defoliation. The grafted clones were derived from mature trees that showed resistance or susceptibility to Budworm defoliation in the forest. All clones were exposed to either Budworm defoliation or nondefoliation treatments in 1998 and 1999 under greenhouse conditions. We found that the total concentration of monoterpenes in current-year foliage varied greatly between two consecutive years in clones in the greenhouse and in their corresponding mature trees in the forest. Fractional composition of different monoterpenes was similar between different years and between clones and mature trees, indicating genetic control of this trait. Two different defoliation experiments were conducted to assess the importance of budburst phenology as a factor determining host plant resistance. In the 1998 experiment, Budworm feeding was matched to the budburst of each individual plant. Monoterpene concentration was high in 1998, and Budworm potential fitness was greater on clones from the resistant mature trees that had lower concentrations of total monoterpenes. In the 1999 experiment, Budworm feeding was matched to budburst of the whole population of plants in order to mimic conditions similar to insects feeding on trees in the field. The concentration of monoterpenes was low in 1999, and Budworm fitness was not related to monoterpenes. Total monoterpene concentration was negatively related to foliar nitrogen concentration, suggesting that C/N balance may affect monoterpene synthesis in needles. However, tree growth was not related to total monoterpene concentration. We concluded that expression of differences in Budworm resistance among Douglas fir genotypes might be caused by interactions among multiple resistance mechanisms such as needle monoterpenes and tree budburst phenology.
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DEFINING THE WESTERN SPRUCE Budworm'S NUTRITIONAL NICHE WITH RESPONSE SURFACE METHODOLOGY'
Ecology, 1993Co-Authors: Karen M. Clancy, Rudy M. KingAbstract:A response surface design was used to help define the "nutritional niche" of the western spruce Budworm, Choristoneura occidentalis. We evaluated how calcium, magnesium, and phosphorus interacted to influence Budworm fitness on artificial diets containing five different levels of the minerals. We quantified survival rates for several life stages using a three-generation bioassay. Data from the bioassay were used to estimate population growth over three complete generations. Performance of the Budworm was affected by Mg (linear response for F. generation; 0.83-1.95 mg/g tested) and P (quadratic response for P, (parental) and F. generations; 2.74-4.95 mg/g tested) but was largely unaffected by Ca (0.50-6.81 mg/g tested). Overall, the results suggested Budworm perfor- mance is best when Mg is at low concentrations and P is at moderate concentrations, and that very high levels of Mg and P are detrimental to the Budworm. On average, host trees had too much Mg and too little P for optimal response by Budworms. Interactions between Mg and P imply that balances or ratios of minerals are important in Budworm nutritional ecology. However, detectable effects from Mg, P, and Ca in the diets diminished as the bioassay continued into the F2 generation, and, consequently, the estimated number of larvae alive at the beginning of the F2 and F3 generations showed no relationship to concentrations of the test minerals. This result probably reflected: (1) the loss of some design points in the second and third generations of the bioassay because larvae did not survive on diets that were markedly suboptimal and (2) increased variability in the pop- ulation growth response as the experiment continued into the F2 and F3 generations.
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western spruce Budworm response to different moisture levels in artificial diets
Forest Ecology and Management, 1991Co-Authors: Karen M. ClancyAbstract:Western spruce Budworm (Choristoneura occidentalis Freeman) performance (survival, larval development time, and pupal biomass) was evaluated for three consecutive generations on artificial diets with four moisture levels: 72%, 76%, 84%, and 88% moisture, for three levels of nitrogen: 1.2%, 1.9%, and 3.9% N dry biomass. Budworm performance was generally negatively associated with food moisture content, rather than positively associated as reported by others. Furthermore, increased moisture in the artificial diets did not improve the efficiency with which the Budworm could utilize the nitrogen in the diets. Budworm survival, pupal biomass, and development time were best on diets with low N and low water or high N and low water. Water appeared simply to be acting as a diluent in these experiments. For the western spruce Budworm the importance of plant water and N as key nutrients for predicting herbivore performance may not be direct cause-and-effect but, rather, to be related to other factors that are linked to these characteristics in plant tissues. Water is not likely to be a critically limiting nutrient when Budworm larvae feed on the new, current-year needles of their conifer hosts. The higher moisture levels tested, 84% and 88%, did not improve larval performance; thus, the Budworm's enhanced growth on early-season, new foliage may not be directly associated with the higher moisture content of new, expanding needles, but is probably related to other factors linked to plant water content.
Éric Bauce - One of the best experts on this subject based on the ideXlab platform.
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Indirect host-mediated effects of an exotic phloem-sap feeder on a native defoliator of balsam fir
Forest Ecology and Management, 2015Co-Authors: Dorthea M. Grégoire, Dan T. Quiring, Lucie Royer, Stephen B. Heard, Éric BauceAbstract:Since its introduction from Europe, balsam woolly adelgid [Adelges piceae (Ratzeburg) (Hemiptera: Adelgidae)], a phloem-sap feeder, has spread throughout the balsam fir [Abies balsamea L. (Mill.)] forests of eastern Canada. Trees under A. piceae attack develop ‘‘gout’’ and differ from unattacked trees in physiology, morphology, growth, and chemistry. The native and eruptive eastern spruce Budworm [Choristoneura fumiferana (Clem.) (Lepidoptera: Tortricidae)] also attacks fir, causing severe defoliation during outbreaks. While balsam woolly adelgid and Budworm feed at different times and on different host tissues, such spatiotemporally separated herbivores may still interact via host-mediated indirect effects. We examined the relationship between gout and the performance of developing Budworm larvae in balsam fir dominated stands in western Newfoundland. We tested for adelgid–Budworm interactions in unthinned and precommercially-thinned (20 years past) stands, because the host’s growing condition can affect foliage composition and herbivore performance. Budworm attained lower pupal weight when reared on trees with high levels of gout. In unthinned stands moderate gout reduced Budworm survivorship, but there was no such effect in thinned stands. Gout did not affect Budworm sex ratio. Although our data are consistent with interactions mediated by foliage quality (rather than quantity), and although Budworm survivorship was associated with several aspects of foliage chemistry (Mg and N, positive; monoterpenes, negative), we were unable to identify specific host quality changes underlying the adelgid–Budworm interaction. Our study demonstrates that A. piceae attack is an important factor influencing Budworm performance, and it should be considered when analyzing Budworm population dynamics and when developing management protocols for forests impacted by A. piceae attack.
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Does spruce Budworm (Lepidoptera: Tortricidae) rearing diet influence larval parasitism?
The Canadian Entomologist, 2013Co-Authors: M. Lukas Seehausen, Jacques Régnière, Éric BauceAbstract:AbstractArtificial diet is commonly used to rear the spruce Budworm, Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae), in the laboratory. While its effect on spruce Budworm performance is relatively well studied, no information exists about the influence of rearing diet on larval parasitism. In this study, spruce Budworm larvae reared in the laboratory on artificial diet or balsam fir, Abies balsamea (Linnaeus) Miller (Pinaceae), foliage were introduced in the field to compare parasitism. Additionally, a laboratory choice test was conducted with the larval parasitoid Tranosema rostrale (Brischke) (Hymenoptera: Ichneumonidae). No significant influence of spruce Budworm rearing diet on parasitism in the field was found. However, in the laboratory, T. rostrale attacked significantly more foliage-fed larvae. We conclude that even if initial differences in parasitism may exist between diet-fed and foliage-fed larvae in the laboratory, spruce Budworm larvae reared on artificial diet can be used in field studies investigating parasitism of wild spruce Budworm populations without concern that the food source would affect parasitism.
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Phenolic compounds that confer resistance to spruce Budworm
Entomologia Experimentalis et Applicata, 2011Co-Authors: Nathalie Delvas, Éric Bauce, Caroline Labbé, Thierry Ollevier, Richard E. BélangerAbstract:Phenolic compounds are apparently important in the defence mechanisms of conifers. To test the hypothesis that phenolic compounds in resistant white spruce [Picea glauca (Moench) Voss (Pinaceae)] impart resistance against spruce Budworm [Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae)], we performed aqueous extractions of current-year shoots of white spruce that were tolerant of varying levels of Budworm defoliation. High-performance liquid chromatographic profiles of water extracts of P. glauca needles differed between resistant and susceptible trees. Further nuclear magnetic resonance analyses identified two phenolic glucosides in susceptible white spruce, picein [3-(β-d-glucosyloxy)-hydroxy-acetophenone] and pungenin [3-(β-d-glucosyloxy)-4-hydroxy-acetophenone], and two phenolics in resistant white spruce, pungenol (3′,4′-hydroxy-acetophenone) and piceol (4′-hydroxyacetophenone). We focused on the performance of spruce Budworm when piceol and pungenol were added to the diet. These two compounds significantly reduced larval survival, retarded development, and reduced pupal mass. Food consumption by sixth-instar spruce Budworms was affected by a combination of the phenolic compounds. These results suggest that the two phenolic compounds reduce the pressure of spruce Budworm herbivory on specific host tree phenotypes. Thus, the mechanism of defence in P. glauca apparently reflects a strategy of constitutive resistance.
Jacques Régnière - One of the best experts on this subject based on the ideXlab platform.
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Density Dependence of Egg Recruitment and Moth Dispersal in Spruce Budworms
Forests, 2019Co-Authors: Jacques Régnière, Vincent G. NealisAbstract:Egg recruitment quantifies the relative importance of realized fecundity and migration rates in the population dynamics of highly mobile insects. We develop here a formal context upon which to base the measurement and interpretation of egg recruitment in population dynamics of eastern and western spruce Budworms, two geographically separated species that share a very similar ecology. Under most circumstances, per capita egg recruitment rates in these Budworms are higher in low-density populations and lower in high-density populations, relative to the regional mean: Low-density populations are nearly always migration sinks for gravid moths, and dense populations nearly always sources. The slope of this relationship, measured on a log scale, is negatively correlated with migration rate, and ranges between 0 and −1. The steeper the slope, the more marked net migration. Using our western spruce Budworm observations, we found strong evidence of density-dependent emigration in Budworms, so migration is not simply a random perturbation in the lagged, density-dependent stochastic process leading to Budworm outbreaks. It is itself statistically and biologically density-dependent. Therefore, moth migration is a synchronizing factor and a spread mechanism that is essential to understanding the development and expansion of spruce Budworm outbreaks at regional scales in the boreal forests of North America.
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Why western spruce Budworms travel so far for the winter
Ecological Entomology, 2016Co-Authors: Vincent G. Nealis, Jacques RégnièreAbstract:1. Conifer-feeding Budworms (Choristoneura) hibernate in sheltered locations on their host trees from late summer of 1 year to spring of the next. During this period, they do not feed but rely on sustenance provided in the egg. Overwinter survival is dependent on the rate of consumption of these limited reserves. 2. A process model was developed that quantifies the relationship between the rate of consumption and survival at variable temperatures and exposure times for western spruce Budworm. The model supported physiological evidence that warm weather conditions early in the diapause period have a dominant influence on overwinter survival. Output compared favourably with field observations of poorer Budworm survival at lower elevations where late-summer and autumn temperatures were warmer compared to those overwintering at cooler, higher elevations. 3. Field experiments demonstrated these weather-dependent rates of survival were modulated significantly by the degree of shelter experienced by hibernating Budworms. 4. Dissection of whole trees harbouring overwintering western spruce Budworms showed a significant portion of the population had travelled a considerable distance from the periphery of the tree canopy where eggs were laid to overwinter successfully on the tree bole where sheltered niches are common. 5. Thus, Budworms will travel relatively long distances and risk increased mortality during this dispersal to find adequate shelter to overwinter.
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Does spruce Budworm (Lepidoptera: Tortricidae) rearing diet influence larval parasitism?
The Canadian Entomologist, 2013Co-Authors: M. Lukas Seehausen, Jacques Régnière, Éric BauceAbstract:AbstractArtificial diet is commonly used to rear the spruce Budworm, Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae), in the laboratory. While its effect on spruce Budworm performance is relatively well studied, no information exists about the influence of rearing diet on larval parasitism. In this study, spruce Budworm larvae reared in the laboratory on artificial diet or balsam fir, Abies balsamea (Linnaeus) Miller (Pinaceae), foliage were introduced in the field to compare parasitism. Additionally, a laboratory choice test was conducted with the larval parasitoid Tranosema rostrale (Brischke) (Hymenoptera: Ichneumonidae). No significant influence of spruce Budworm rearing diet on parasitism in the field was found. However, in the laboratory, T. rostrale attacked significantly more foliage-fed larvae. We conclude that even if initial differences in parasitism may exist between diet-fed and foliage-fed larvae in the laboratory, spruce Budworm larvae reared on artificial diet can be used in field studies investigating parasitism of wild spruce Budworm populations without concern that the food source would affect parasitism.
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Risk of Dispersal in Western Spruce Budworm
Agricultural and Forest Entomology, 2009Co-Authors: Vincent G. Nealis, Jacques RégnièreAbstract:1 Western spruce Budworm Choristoneura occidentalis Free. larvae emerge in the spring before buds have expanded and spend a variable period of time foraging on branches and mining needles. 2 Losses of dispersing Budworms during this needle-mining period are related directly to the severity of defoliation in previous years and inversely related to foliage biomass in the study plot and to temperature and rainfall during the needle-mining period. 3 Losses can be interpreted in terms of risk of dispersal, which is the product of the propensity of early-stage Budworms to disperse in search of resources and the consequences of this behaviour for survival under variable ecological conditions. 4 A comparison of the species-specific nature of risk of dispersal in three conifer-feeding Budworm systems of North America may elucidate the common nature but variable features of their respective population dynamics.
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Insect-host relationships influencing disturbance by the spruce Budworm in a boreal mixedwood forest
Canadian Journal of Forest Research, 2004Co-Authors: Vincent G. Nealis, Jacques RégnièreAbstract:V.G. Nealis and J. Regniere Abstract: 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 cy- cle. 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.
David A. Maclean - One of the best experts on this subject based on the ideXlab platform.
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Protection Strategy against Spruce Budworm
Forests, 2019Co-Authors: David A. MacleanAbstract:Spruce Budworm is one of the most significant forest insects worldwide, in terms of outbreak extent, severity, and economic impacts. As a defoliator, spruce Budworm larvae are susceptible to insecticide protection, and improvements in efficacy and reductions in non-target environmental effects have made such protection attractive. In this Special Issue, 12 papers describe the advances in spruce Budworm protection, most notably an ‘early intervention strategy’ approach that after six years of trials in New Brunswick, Canada, shows considerable success to date in reducing Budworm outbreak occurrence and severity.
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Modeling Insect Disturbance Across Forested Landscapes: Insights from the Spruce Budworm
Simulation Modeling of Forest Landscape Disturbances, 2015Co-Authors: Brian R. Sturtevant, Barry J. Cooke, Daniel Kneeshaw, David A. MacleanAbstract:Irruptive forest insects have a rich history of empirical study and as subjects of modeling in both theoretical and applied ecology, yet compared with other disturbance agents landscape-scale insect disturbance modeling is rare. We examine the history of spruce Budworm (Choristoneura fumiferana) disturbance modeling to provide insight into landscape-scale insect disturbance modeling more generally. First, we outline the evolution of competing approaches to Budworm population modeling, illustrating the interplay of models and data, and highlighting the roles of reciprocal feedbacks among trophic levels (i.e., Budworm, its forest host and its natural enemies) and broader-scale processes (i.e., dispersal, synchronization, climatic variation and change). We then overview studies relating Budworm defoliation to its effects on forests, culminating in spruce Budworm decision support tools designed for forest operations planning. Modeling applications using landscape disturbance and succession models are a more recent addition, focused on long-term responses of forested landscapes to a given Budworm disturbance regime. Cross-scale interactions—recognized within the Budworm–forest system for over three decades—demand sophisticated analyses and modeling that will ultimately lead to a more robust synthesis of Budworm response to forest conditions, particularly under different climatic contexts. We describe the Budworm case study to illustrate how insights from divergent perspectives can be complementary and ultimately lead to more complete understanding of the system. We propose that the most fruitful modern avenue of research in forest–insect–climate interactions is in testing inclusive hypotheses that allow for multiple processes acting simultaneously using integrative, multiscale landscape models that embrace the possible existence of a range of dynamic behaviors.
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Future Spruce Budworm Outbreak May Create a Carbon Source in Eastern Canadian Forests
Ecosystems, 2010Co-Authors: Caren C. Dymond, David A. Maclean, Eric T. Neilson, Graham Stinson, Kevin Porter, David R. Gray, Michel Campagna, Werner A. KurzAbstract:Spruce Budworm ( Choristoneura fumiferana Clem.) is an important and recurrent disturbance throughout spruce ( Picea sp.) and balsam fir ( Abies balsamea L.) dominated forests of North America. Forest carbon (C) dynamics in these ecosystems are affected during insect outbreaks because millions of square kilometers of forest suffer growth loss and mortality. We tested the hypothesis that a spruce Budworm outbreak similar to those in the past could switch a forest from a C sink to a source in the near future. We used a model of ecosystem C to integrate past spruce Budworm impact sequences with current forest management data on 106,000 km^2 of forest in eastern Québec. Spruce Budworm-caused mortality decreased stand-level merchantable C stocks by 11–90% and decreased ecosystem C stocks by 2–10% by the end of the simulation. For the first 13 years (2011–2024), adding spruce Budworm significantly reduced ecosystem C stock change for the landscape from a sink (4.6 ± 2.7 g C m^−2 y^−1 in 2018) to a source (−16.8 ± 3.0 g C m^−2 y^−1 in 2018). This result was mostly due to reduced net primary production. The ecosystem stock change was reduced on average by 2 Tg C y^−1 for the entire simulated area. This study provides the first estimate that spruce Budworm can significantly affect the C sink or source status of a large landscape. These results indicate that reducing spruce Budworm impacts on timber may also provide an opportunity to mitigate a C source.
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future spruce Budworm outbreak may create a carbon source in eastern canadian forests
Ecosystems, 2010Co-Authors: Caren C. Dymond, David A. Maclean, Eric T. Neilson, Graham Stinson, David R. Gray, Michel Campagna, Kevin B Porter, Werner A. KurzAbstract:Spruce Budworm (Choristoneura fumiferana Clem.) is an important and recurrent disturbance throughout spruce (Picea sp.) and balsam fir (Abies balsamea L.) dominated forests of North America. Forest carbon (C) dynamics in these ecosystems are affected during insect outbreaks because millions of square kilometers of forest suffer growth loss and mortality. We tested the hypothesis that a spruce Budworm outbreak similar to those in the past could switch a forest from a C sink to a source in the near future. We used a model of ecosystem C to integrate past spruce Budworm impact sequences with current forest management data on 106,000 km2 of forest in eastern Quebec. Spruce Budworm-caused mortality decreased stand-level merchantable C stocks by 11–90% and decreased ecosystem C stocks by 2–10% by the end of the simulation. For the first 13 years (2011–2024), adding spruce Budworm significantly reduced ecosystem C stock change for the landscape from a sink (4.6 ± 2.7 g C m−2 y−1 in 2018) to a source (−16.8 ± 3.0 g C m−2 y−1 in 2018). This result was mostly due to reduced net primary production. The ecosystem stock change was reduced on average by 2 Tg C y−1 for the entire simulated area. This study provides the first estimate that spruce Budworm can significantly affect the C sink or source status of a large landscape. These results indicate that reducing spruce Budworm impacts on timber may also provide an opportunity to mitigate a C source.
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potential wood supply losses to spruce Budworm in new brunswick estimated using the spruce Budworm decision support system
Forestry Chronicle, 2002Co-Authors: David A. Maclean, Kevin B Porter, Kathy P Beaton, Wayne E Mackinnon, M G BuddAbstract:The Spruce Budworm Decision Support System (SBW DSS) was used to estimate potential volume losses to a future spruce Budworm (Choristoneura fumiferana (Clem.)) outbreak in New Brunswick. The SBW DS...
