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With the rapid trend in the climate shift, the spruce budworm (SBW) (Choristoneura fumiferana), is increasing its damage and distribution area making forests more vulnerable. Despite its major ecological implications, challenges remain in understanding the historical impact of climate on defoliation caused by the SBW, the severity of its impact on host trees and how it has changed over time. Thus, we aim to evaluate the trend and the impact of climate on SBW outbreaks during the last century and to reconstruct the spatiotemporal patterns in Quebec. For this, we will use the dendrochronological time series, as well as complementary fieldwork, and use the climate datasets to model climate normalized growth. We will extract the rate and the extent of the impact of the defoliating insect, and its interaction with climate, on the boreal stands. This study will provide invaluable information to understand major ecological shifts caused by the defoliator and the climate at a spatiotemporal scale.
Evaluate the effect of climate during the
outbreak period on the growth of the
boreal stands over the years
Extract the rate and the extent of impact
of the defoliating insect, and its
interaction with climate, on the boreal
Help understand ecological shifts at a
spatiotemporal scale
The results of this project will help on
future climate to predict a general trend
in the range and severity of future
Understanding complex interactions in forest
ecosystems: climate and insect outbreaks
Anoj Subedi, Miguel Montoro Girona, Philippe Marchand, Hubert Morin, Marie-Josée Fortin, @subedi_aj
Natural disturbances are major drivers in
forest ecosystems, affecting the structure
and function.
Climate change affect the vulnerability of
host species to defoliation
Spruce budworm (SBW) (Choristoneura
fumiferana),is the main defoliator in the
Eastern Canadian forest
Increase in the severity (% of affected
trees) of SBW during the last century
Expansion, to the north, and increase of
frequency and severity
Changing climate scenarios
Effect of budworm attack on black spruce
Photo by: Lavoie & Montoro Girona
Hypothesis Methods
Climate change
Increase in
in Black
Dendrochronological time
series data integrating more
than 10 diferent projects
from the Ministry
Complementary field works
Climatic data
Climate datasets of
the last century
(WorldClim data)
Study area
Location of study sites in Quebec. The different colors
correspond to the various original datasets
Lavoie, J.; Montoro Girona, M.; Morin, H. Vulnerability of Conifer Regeneration to
Spruce Budworm Outbreaks in the Eastern Canadian Boreal Forest. Forests 2019, 10,
Montoro Girona, M.; Navarro, L.;Morin, H. A Secret Hidden in the Sediments:
Lepidoptera Scales. Front. Ecol. Evol. 2018, 6, 1-5.
Navarro, L.; Morin, H.; Bergeron, Y.; Girona, M.M. Changes in spatiotemporal patterns
of 20th century spruce budworm outbreaks in eastern Canadian boreal forests. Plant Sci.
2018, 9, 19051920.
Identify the influence of different
climate scenarios on the dynamics
of spread and severity of epidemics
Evaluate the trend and the impact
of climate on SBW outbreaks
during the last century
Calibrate & redo the spatiotemporal
Climate change affects the severity
of black spruce epidemics due to the
better synchronization of bud /
budworm emergence
Climate normalized growth during
absence/presence of SBW (presence
recorded by MFFP through aerial surveys)
Evaluate the effect of budworm outbreak
of growth as a function of climate
“Compare the predicted climate effect on
the reduction of growth during an
Dendroecological data
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Full-text available
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.
Full-text available
In scenarios of future climate change, there is a projected increase in the occurrence and severity of natural disturbances inboreal forests. Spruce budworm (Choristoneura fumiferana)(SBW) is the main defoliator of conifer trees in the North American boreal forests affecting large areas and causing marked losses of timber supplies. However, the impact and the spatiotemporal patterns of SBW dynamics at the landscape scale over the last century remain poorly known. This is particularly true for northern regions dominated by spruce species. The main goal of this study is to reconstruct SBW outbreaks during the 20th century at the landscape scale and to evaluate changes in the associated spatiotemporal patterns in terms of distribution area, frequency, and severity. We rely on a dendroecological approach from sites within the eastern Canadian boreal forest and draw from a large dataset of almost 4,000 trees across a study area of nearly 800,000 km2. Interpolation and analyses of hotspots determined reductions in tree growth related to insect outbreak periods and identified the spatiotemporal patterns of SBW activity over the last century. The use of an Ordinary Least Squares model including regional temperature and precipitation anomalies allows us to assess the impact of climate variables on growth reductions and to compensate for the lack of non-host trees in northern regions. We identified three insect outbreaks having different spatiotemporal patterns, duration, and severity. The first (1905–1930) affected up to 40% of the studied trees, initially synchronizing from local infestations and then migrating to northern stands. The second outbreak (1935–1965) was the longest and the least severe with only up to 30% of trees affected by SBW activity. The third event (1968–1988) was the shortest, yet it was also the most severe and extensive, affecting nearly up to 50% of trees and 70% of the study area. This most recent event was identified for the first time at the limit of the commercial forest illustrating a northward shift of the SBW distribution area during the 20th century. Overall, this research confirms that insect outbreaks are a complex and dynamic ecological phenomena, which makes the understanding of natural disturbance cycles at multiple scales a major priority especially in the context of future regional climate change.