Skip to main content
SLU publication database (SLUpub)

Research article2022Peer reviewedOpen access

Insect defoliation modulates influence of climate on the growth of tree species in the boreal mixed forests of eastern Canada

Boakye, Emmanuel Amoah; Houle, Daniel; Bergeron, Yves; Girardin, Martin P.; Drobyshev, Igor


Increasing air temperatures and changing precipitation patterns due to climate change can affect tree growth in boreal forests. Periodic insect outbreaks affect the growth trajectory of trees, making it difficult to quantify the climate signal in growth dynamics at scales longer than a year. We studied climate-driven growth trends and the influence of spruce budworm (Choristoneura fumiferana Clem.) outbreaks on these trends by analyzing the basal area increment (BAI) of 2058 trees of Abies balsamea (L.) Mill., Picea glauca (Moench) Voss, Thuja occidentalis L., Populus tremuloides Michx., and Betula papyrifera Marsh, which co-occurs in the boreal mixedwood forests of western Quebec. We used a generalized additive mixed model (GAMM) to analyze species-specific trends in BAI dynamics from 1967 to 1991. The model relied on tree size, cambial age, degree of spruce budworm defoliation, and seasonal climatic variables. Overall, we observed a decreasing growth rate of the spruce budworm host species, A. balsamea and P. glauca between 1967 and 1991, and an increasing growth rate for the non-host, P. tremuloides, B. papyrifera, and T. occidentalis. Our results suggest that insect outbreaks may offset growth increases resulting from a warmer climate. The observation warrants the inclusion of the spruce budworm defoliation into models predicting future forest productivity.


boreal mixedwoods; climate change; dendrochronology; hardwoods; insect outbreak; natural disturbances

Published in

Ecology and Evolution
2022, Volume: 12, number: 3, article number: e8656Publisher: WILEY

    Sustainable Development Goals

    SDG13 Climate action
    SDG15 Life on land

    UKÄ Subject classification

    Forest Science

    Publication identifier


    Permanent link to this page (URI)