The mystery of tree-rings regarding climate and insect outbreak interactions - A methodological challenge

Abstract

Current models predict profound effects of global change on forest ecosystems; in particular, natural disturbances will increase in frequency and severity. Recognized as the most important defoliator of North America, spruce budworm (SBW) (Choristoneura fumiferana) has a major impact on the boreal forest dynamic. Compared with historical outbreaks, more recent SBW outbreaks show a shift in range and severity, making the boreal forest more vulnerable in the face of climate change. However, methodological challenges remain in understanding the complex interaction between climate and spruce budworm defoliation to improve our predictions of forest dynamics under global change scenarios. Our goal is to reconstruct the spatiotemporal patterns and evaluate the interaction effect between climate and SBW defoliation on black spruce (Picea mariana) growth during the last century. To this end, we will rely on the largest dendrochronological database (> 800 sampling plots) distributed approximately around an area of 900,000 km2 within Quebec; from which approximately 5,500 cross-dated black-spruce trees that cover the outbreaks periods of the last century (age ≥ 100 years) will be selected. After removing tree-specifics effects on growth, the impact of the climatic variables on growth will be compared during the presence and absence of an outbreak to identify the interaction of climate and defoliation on growth. We will use program software to interpolate location-specific weather data of the last century and a defoliation map produced by MFFP through an aerial survey for the past 52 years. We expect to understand the interaction of SBW with climate, more precisely, the effect of specific climatic parameters on SBW and black spruce defoliation during the outbreak. Such results can have profound implications in predicting the impact of SBW on shifting climate scenarios to obtain a general trend in the range and severity of future outbreak periods, which is crucial for managing boreal forests under climate change.

Full text

Context
Objectives
Novelty
SBW
CC
Severity of defoliation in
the context of climate
change (Pureswaran et al.2015)
Methodology
The mystery : narrow tree rings caused by an insect (H)
The defoliation map (2020) of Quebec produced by MFFP
The location of study sites in Quebec
References
QUEBEC Contribution
The mystery of tree-rings regarding climate and insect
outbreak interactions: A methodological challenge
Anoj Subedi, Miguel Montoro Girona, Philippe Marchand, Hubert Morin, Yves Bergeron
Dendroecological data
Biggest data base of black spruce in
Quebec for the last century
Cross dated 5500 black spruce trees (age ≥
100 years)
Evaluate the influence of climatic
parameters on the severity and the spread
of the SBW outbreak
Analyze the SBW outbreak in black spruce
during the last century to better understand
the effect of defoliation and climate change
Defoliation survey (MFFP)
Climatic datasets
Interpolation using BioSIM
Modeling
Interaction effect of SBW and climatic
parameters on the defoliation of black
spruce
Spatial & temporal range, data, &
approaches
Provides a new parameter to predict the
dynamism of SBW impact over periods
Contribute to obtain a general trend in the
range and severity of future outbreak
periods, which is crucial for managing
boreal forests under climate change.
Lavoie, J.; Montoro Girona, M.; Morin, H. Vulnerability of Conifer Regeneration to Spruce
Budworm Outbreaks in the Eastern Canadian Boreal Forest. Forests 2019,10,850.
Navarro, L.; Morin, H.; Bergeron, Y.; Girona, M.M. Changes in spatiotemporal patterns of 20th
century spruce budworm outbreaks in eastern Canadian boreal forests. Front. Plant Sci. 2018,
9, 1905–1920.
Pureswaran, D. S.; Grandpré, L. De;Paré, D.; Taylor, A.; Barrette, M.; Morin, H.; Régnière, J.;
Kneeshaw, D. D. Climate-induced changes in host tree-insect phenology may drive ecological
state-shift in boreal forest. Ecology 2015,96(6), 1480–1491.
Boreal and northern temperate zone of
Quebec
Natural disturbances
Insect outbreak
Spruce budworm (SBW)
Defoliation
Black spruce (Picea mariana)
Study area