PosterPDF Available

Abstract

Climate is the main driver of natural disturbance regimes in forest ecosystems. One example of this influence is the current spruce budworm (Choristoneura fumiferana) (SBW) outbreak in eastern Canada. The persistent defoliation by SBW over years has altered the growth and survival of the host trees greatly. Even though black spruce (Picea mariana) is a secondary host for this defoliator, its impact on growth is strong during the outbreak. The objective of this research is to evaluate the influence of climatic variables on the growth of black spruce during an outbreak period. We hypothesized that the temperature of the spring months has more effect on growth reduction than the precipitation during an outbreak. To reach this goal, we assembled an exceptional dendrochronological database from 10 projects around Québec over the last three decades. To link tree-ring growth to climate within the outbreak, the defoliation maps produced by MFFP were used as an indicator for budworm presence. Due to the major influence on the phenology and biology of the budworm and black spruce, climate data were compiled and interpolated using BioSIM software. Our preliminary findings from 13 sites located within south-western Québec revealed that the temperature during the spring months had a significant influence on black spruce growth, but precipitation had a lower impact for the same sites in compared to temperature; specifically, June temperature for the current and the previous year was identified as an important climate variable to alter growth during the SBW outbreak. This research will contribute to improving our understanding of SBW-climate and growth interactions, which could be essential to establishing forest management strategies in the face of climate change.
Objective
Hypothesis
Preliminary results
Evaluate the influence of climatic variables on the growth of black spruce
during outbreak period
Temperature of the spring months has more effect on growth
reduction than the precipitation during an outbreak
Introduction
Methodology
Study area:
Data compilation:
Dendrochronology + Climate data + Defoliation survey
Additional results
Contribution
Identification of site-specific growth index for black
spruce, climate variables, and defoliation intensity
Modeling:
Building linear and non-linear
mixed effect models
Growth = 1.3 - 0.02 * Temperature
From 14 sites within south-western Quebec
Significant impact of temperature on growth
(not of precipitation)
Upcoming results of the models will identify more climatic
variables that shows significant impact on the growth indices
of black spruce during different defoliation levels
Support to understand the alternation of growth
during outbreak in the face of climate change
Climate
change Natural disturbances Spruce budworm
outbreak
Anoj.Subedi@uqat.ca
Monthly average temperature (°C)
Coefficients
Coefficients
Average precipitation (mm of water)
May and June temperature strongly correlated with the
growth during the outbreak period (1968-1988)
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References:
Area - 900,000
km2
QUEBEC
Around 4000
trees
206 sites from
13 previous
projects
Anoj Subedi1, Miguel Montoro Girona1, Philippe Marchand1, Yves Bergeron1, Hubert Morin2
1Institut de Recherche sur les Forêts, Université du Québec en Abitibi-Témiscamingue, Canada
2Département des Sciences fondamentales, Université du Québec à Chicoutimi, Canada
Understanding how tree-growth is driven by the climate during the
spruce budworm outbreak
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