Partial windthrow as a driving process of forest dynamics in old-growth boreal forests

2014 ◽  
Vol 44 (10) ◽  
pp. 1165-1176 ◽  
Author(s):  
François Girard ◽  
Louis De Grandpré ◽  
Jean-Claude Ruel
Keyword(s):  
Boreal Forest ◽  
Forest Dynamics ◽  
Boreal Forests ◽  
Tree Mortality ◽  
Stand Structure ◽  
Temporal Dynamics ◽  
Spruce Budworm ◽  
Climatic Conditions ◽  
Balsam Fir ◽  
Vegetation Development

As climate changes, boreal forest ecosystems may become subject to disturbances that were previously uncommon in some regions. In recent decades, large tracts of northeastern boreal forest of Canada have been affected by different types of climatic events causing a lot of partial and some total stand mortality. Since these disturbances may become more important drivers of forest dynamics, there is a need to document their impact on forest structure. The objectives of this study were to describe temporal dynamics of partial windthrows and determine the effect of partial windthrow on stand composition and understory vegetation. The study was conducted in the North-Shore region of Quebec (Canada). Eighteen plots in closed forests were paired with 18 adjacent windthrow areas, in which trees experienced similar edaphic and climatic conditions. Dendroecological analyses, combined with vegetation sampling, were conducted on each site to determine stand structure and vegetation development through time. Significant increases in balsam fir and shade-tolerant species were observed in windthrow gaps. Tree mortality in windthrown stands was a slow process until the mid-1990s, a period during which spruce budworm defoliation may have played a role in weakening trees and making them more vulnerable to partial windthrow. Greater mortality observed following the mid-1990s was most certainly related to a regional storm. The initial composition of stands plays an important role in driving postwindthrow succession, as balsam fir is more susceptible to treefall. As opposed to stand-replacing windthrow and spruce budworm outbreaks that generate various postdisturbance responses, partial windthrow appears to only create opportunities for pre-established balsam fir to undergo release in gaps.

scholarly journals Splitting in Fire-Killed Trees in the Boreal Forest of Alberta

2003 ◽  
Vol 20 (4) ◽  
pp. 167-174
Author(s):  
Nobutaka Nakamura ◽  
Paul M. Woodard ◽  
Lars Bach
Keyword(s):  
Boreal Forest ◽  
Boreal Forests ◽  
Black Spruce ◽  
Lodgepole Pine ◽  
White Spruce ◽  
Balsam Fir ◽  
Crown Fire ◽  
In Fire ◽  
Solar Angle

Abstract Tree boles in the boreal forests of Alberta, Canada will split once killed by a stand-replacing crown fire. A total of 1,485 fire-killed trees were sampled, 1 yr after burning, in 23 plots in 14 widely separated stands within a 370,000 ha fire. Sampling occurred in the Upper and Lower Foothills natural subregions. The frequency of splitting varied by species but averaged 41% for all species. The order in the frequency of splitting was balsam fir, black spruce, white spruce and lodgepole pine. The type of splitting (straight, spiral, or multiple) varied by species, as did the position of the split on the tree bole. Aspect or solar angle was not statistically related to the type or occurrence of splitting.

scholarly journals THE VULNERABILITY OF BALSAM FIR TO SPRUCE BUDWORM ATTACK IN NORTHWESTERN ONTARIO, WITH SPECIAL REFERENCE TO THE PHYSIOLOGICAL AGE OF THE TREE

1958 ◽  
Vol 34 (4) ◽  
pp. 405-422 ◽  
Author(s):  
J. R. Blais
Keyword(s):  
Special Reference ◽  
Tree Mortality ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Site Quality ◽  
Physiological Age ◽  
Northwestern Ontario ◽  
Relationship Of ◽  
The Relationship ◽  
Relative Vulnerability

The annual defoliation by spruce budworm and the progressive mortality of balsam fir trees were recorded in nine study plots in northwestern Ontario over a period of 11 years. In addition to general observations on the relationship of tree mortality to defoliation, some information was obtained on the relative vulnerability of the trees with respect to size, physiological age (flowering condition), and vigor (site quality).

Effects of Spruce Budworm Outbreaks on the Productivity and Stability of Balsam Fir Forests

1984 ◽  
Vol 60 (5) ◽  
pp. 273-279 ◽  
Author(s):  
David A. MacLean
Keyword(s):  
Tree Mortality ◽  
Choristoneura Fumiferana ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Wood Production ◽  
Ecological Stability ◽  
Short Term ◽  
Eastern Canada ◽  
Feasible Method ◽  
Human Usage

Effects of spruce budworm (Choristoneura fumiferana (Clem.)) outbreaks on the productivity and stability of forests in eastern Canada are reviewed and discussed. Defoliation results in reduced growth of trees, widespread tree mortality, and loss of wood production, and thereby causes major forest management problems. At present, the only feasible method for limiting damage and losses from budworm outbreaks over large areas is to apply chemical or biological insecticides periodically to kill larvae and protect the forest from defoliation and tree mortality. Although budworm outbreaks definitely disrupt the wood-producing capacity of forests (or the short-term "stability of forests for human usage"), in terms of overall ecological stability, outbreaks apparently act as a cycling mechanism that allows advance fir-spruce regeneration to succeed the fir-spruce overstory.

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.

Accuracy of aerial sketch-mapping estimates of spruce budworm defoliation in New Brunswick

1996 ◽  
Vol 26 (12) ◽  
pp. 2099-2108 ◽  
Author(s):  
David A. MacLean ◽  
Wayne E. MacKinnon
Keyword(s):  
Decision Support ◽  
New Brunswick ◽  
Decision Support Systems ◽  
Tree Mortality ◽  
Support Systems ◽  
Spruce Budworm ◽  
Weather Conditions ◽  
Balsam Fir ◽  
Small Aircraft

The accuracy of aerial sketch-mapping estimates of spruce budworm (Choristoneurafumiferana (Clem.)) defoliation was evaluated from 1984 to 1993 in 222–325 sample plots in spruce (Picea sp.)–balsam fir (Abiesbalsamea (L.) Mill.) stands in New Brunswick. Operational aerial defoliation estimates were used, wherein all productive forest in known budworm infestation zones was surveyed each year from small aircraft with flight lines 2–5 km apart, and rated in classes of nil (0–10%), light (11–30%), moderate (31–70%), and severe (71–100%). Aerial defoliation estimates were compared with ground-based binocular estimates of current defoliation for an average of 10 trees/plot (range 5–20). Overall, 56% of plots were correctly rated by aerial sketch mapping in four classes (nil, light, moderate, and severe), with 37% of the plots underestimated and 7% overestimated. The predominant error (26% of plots) was rating defoliation as nil (0–10%) from the air when it was actually light (11–30%). This error was deemed not important in terms of predicting tree response, since data from the literature indicated that defoliation less than 30% did not cause tree mortality, although if continued, it would reduce growth. Using three defoliation classes (by combining nil and light, 0–30%), 82% of the plots were correctly classified by aerial sketch mapping. The probability of correct aerial classification of defoliation was significantly affected by defoliation class, weather conditions prior to and during observation flights, and the defoliation class × weather interaction. It was concluded that aerial sketch mapping of spruce budworm defoliation is a viable technique that can be used for both surveys and decision support systems that estimate forest response to budworm outbreaks and management activities.

Balsam fir mortality following the last spruce budworm outbreak in northwestern Quebec

1995 ◽  
Vol 25 (8) ◽  
pp. 1375-1384 ◽  
Author(s):  
Yves Bergeron ◽  
Alain Leduc ◽  
Claude Joyal ◽  
Hubert Morin
Keyword(s):  
Stand Structure ◽  
Management Strategies ◽  
Basal Area ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Forest Composition ◽  
Regression Analyses ◽  
Site Characteristics ◽  
Forest Mosaic ◽  
Independent Effects

Balsam fir (Abiesbalsamea (L.) Mill.) mortality caused by the last spruce budworm (Choristoneurafumiferana (Clem.)) outbreak (1970–1987) was studied in 624 sites belonging to a complex natural forest mosaic originating from different fires in northwestern Quebec. Multiple regression analyses were used to assess the respective effects of stand structure, species composition, site characteristics, and the forest composition surrounding the stand on observed stand mortality. Mortality was observed to increase in relation to diameter of the trees, basal area of balsam fir, and the number of stands dominated by conifers in the forest mosaic. All of these factors showed significant independent effects, but 60% of the variance remained unexplained. Site characteristics, however, did not show a significant relationship to stand mortality. The results suggest that forest composition at both the stand and the forest mosaic levels may be responsible for differing degrees of defoliation that result in differences in stand mortality. Forest management strategies that favor the presence of mixed compositions both at the stand level and at the mosaic level may contribute to decreased stand vulnerability.

Determinants of ~1000-year woody vegetation dynamics at the southern boreal forest margin in Northeast China

2020 ◽  
Author(s):  
Chenyi Zhu ◽  
Hongyan Liu ◽  
Hongya Wang ◽  
Siwen Feng ◽  
Yue Han
Keyword(s):  
Boreal Forest ◽  
Boreal Forests ◽  
Carbon Stock ◽  
Vegetation Change ◽  
Vegetation History ◽  
Permafrost Degradation ◽  
Vegetation Development ◽  
Southern Boundary ◽  
Complete Replacement ◽  
Permafrost Thawing

<p>The most dramatic permafrost degradation is expected to occur at its southernmost distribution, which causes significant vegetation changes in the southernmost boreal forests and consequently affects the carbon stock. To reveal determinants of vegetation change and, in particular, the role of permafrost dynamics, the reconstruction of the long- term vegetation history spanning a warming-cooling cycle is required. Here, we showed that over the last 990 years, vegetation development was characterized by changes in the relative proportions of taxa, such as<em> Larix</em>, <em>Pinus</em> and <em>Corylus</em>, corresponding to the variation in temperature. However, since ~1950 AD, rapid warming has led to the breakdown of the stable relationship among vegetation, climate and permafrost, and the proportion of conifers has shown an increasing trend in the short term due to the influence of permafrost thawing regulated by terrain. In general, we have observed that the coupling system of vegetation, climate and permafrost was stable before ~1950 AD; however, there has been a transition in the most recent rapid warming-induced permafrost thawing. As the southern boundary of permafrost moves northward, it is suspected that the boreal forest in this region will be unstable or may even collapse in the future, and the complete replacement of conifers by broad-leaved trees could greatly reduce the carbon stock in this area by that time.</p>

Fifty years of forest dynamics following diameter-limit cuttings in balsam fir – yellow birch stands of the Lower St. Lawrence region, Quebec

2006 ◽  
Vol 36 (11) ◽  
pp. 2745-2755 ◽  
Author(s):  
Louis Archambault ◽  
Claude Delisle ◽  
Guy R Larocque ◽  
Luc Sirois ◽  
Pierre Belleau
Keyword(s):  
Forest Dynamics ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Betula Alleghaniensis ◽  
Yellow Birch ◽  
Cover Type ◽  
Advance Regeneration ◽  
Observation Area ◽  
Winter Logging

The long-term effects of high-intensity diameter-limit cuttings conducted in the winter and summer of the 1940s and 1950s on the dynamics of softwood and mixedwood stands in southeastern Quebec were compared. Changes in composition and stand structure over a 50 year period were studied using 18 permanent sample plots located in the Lac-Métis Seigneury observation area measured in 1950, 1960, 1970, and 2003. Winter logging operations were conducted between 1942 and 1949, and summer logging operations were conducted between 1958 and 1960. The interaction between cuttings and the 1950s and 1970s spruce budworm (Choristoneura fumiferana (Clemens)) outbreaks that occurred in the area affected forest dynamics. For the two logging operation types, the most abundant softwood species observed before logging and in 2003 was balsam fir (Abies balsamea (L.) Mill.), whereas white birch (Betula papyrifera Marsh.) and yellow birch (Betula alleghaniensis Britt.) were the most abundant hardwood species. Changes in the overstory composition were more significant in the summer logging operations than in the winter ones. The softwood cover type observed before winter logging was maintained in 2003. Following summer logging, an important increase in the proportion of birch species was observed. The softwood cover type observed before logging had changed to a mixedwood cover type by 2003. Forest dynamics differences between the two types of logging were the result of interactions between the density and composition of advance regeneration, the microsite conditions after logging, and the length and severity of spruce budworm outbreaks.

An evaluation of growth response of young, spaced balsam fir to 3 years of spruce budworm spraying with Bacillusthuringiensis

1984 ◽  
Vol 14 (3) ◽  
pp. 404-411 ◽  
Author(s):  
H. Piene ◽  
D. A. MacLean
Keyword(s):  
Growth Response ◽  
Tree Mortality ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Growth Responses ◽  
Average Volume ◽  
Cape Breton ◽  
Volume Increment ◽  
Total Gain

Growth response of young, spaced balsam fir (Abiesbalsamea (L.) Mill.) to 3 successive years (1979–1981) of treatment with Bacillusthuringiensis Berliner for spruce budworm (Choristoneurafumiferana (Clem.)) control was examined in 20 plots on the Cape Breton Highlands, Nova Scotia. Defoliation commenced in 1976, 3 years before control operations began. Five plots were established both inside and outside the spray block, in areas that had been severely defoliated by budworm and in areas moderately defoliated. All plots in the severely defoliated area suffered heavy tree mortality, but mortality was significantly lower in the protected plots. In contrast, the moderately defoliated plots suffered virtually no tree mortality. The average volume increment of stem-analyzed trees from 1979 to 1981 was 0.63 dm3/tree for protected and 0.43 dm3/tree for unprotected trees in the severely defoliated area versus 4.15 dm3/tree for protected and 3.08 dm3/tree for unprotected trees in the moderately defoliated area. These volume increment values are equivalent to 8.8 m3/ha of growth between 1979 and 1981 for protected plots in the moderately defoliated area, compared with 6.1 m3/ha for unprotected plots. Therefore, a total gain of 2.7 m3/ha can be attributed to the 3 years of B. thuringiensis spraying. Long-term growth responses toB. thuringiensis spraying were not evaluated. Better results would be expected had protection started at the beginning of the budworm outbreak, instead of after 3 years of severe defoliation.

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