An analysis of Quebec’s forest inventory data developed by Concordia researchers reveals that the conifer population is on the rebound after decades of decline.
The growth is driven by an increase in the population of balsam fir, which may reflect a recovery from the last major spruce budworm outbreak (1972 to 1986). This outbreak severely impacted the conifer population in large parts of Quebec.
Published in the Journal of Forestry Research , the study combines open access data from the Quebec government’s long-term forest inventory with a new, AI-trained method of interpreting satellite imagery created by the authors.
“We wanted to see if Quebec’s forests were changing and, if so, would this change be captured using satellite imagery,” says lead author Jennifer Donnini , a PhD candidate in the Department of Geography, Planning and Environment .
“Understanding this change is important, because the proportion of conifer and deciduous trees can affect forest structure, wildlife habitat, regeneration and how the forest responds to disturbances like insects, fire or harvesting.”
Professor Angela Kross co-authored the study.
The researchers examined nearly 1,800 permanent forest inventory plots across Quebec’s deciduous, mixed and boreal forest regions between 1985 and 2021. The team tracked changes in the proportion of forest made up of conifer species, a measure that reflects how much physical space conifers occupy within a forest stand relative to broadleaf species.
Almost half of all plots studied showed an increase in conifer composition over the study period. The strongest gains occurred in mixed forests, where more than 60 per cent of plots had increases. The researchers also found that forest stands shifted consistently toward becoming more conifer-dominant over time, with virtually no evidence of the reverse trend.
While the importance of the balsam fir population increased across all forest regions, deciduous species such as paper birch, trembling aspen and sugar maple saw their relative importance decline.
The researchers believe the increase in conifers is likely part of a natural cycle rather than an unusual ecological shift. After insect outbreaks or logging disturbances open forest canopies, fast-growing deciduous species often expand quickly. But over time, shade-tolerant conifers such as balsam fir gradually return and regain dominance as forests mature.
“Balsam fir is shade tolerant, meaning it can live in low light conditions and wait for a broadleaf tree like the paper birch to be affected by some sort of disturbance,” Donnini explains. “Then it can grow into the canopy again and become the dominant species, which is what we believe is happening after three decades of decline.”
The researchers suggest that repeated outbreaks of forest tent caterpillar, which targets hardwood species such as birch and aspen, may also have contributed to favourable conditions for fir regeneration.
One of the study’s major innovations was combining ground-based forest inventory plots with satellite imagery. The relatively simple model uses only four variables from summer and winter satellite images to track long-term forest composition change over time.
The satellite model successfully reproduced broad regional trends observed in the field data, including the significant increase in conifers cover over time. While the system was less accurate at detecting fine-scale changes within individual plots, it proved an effective way to monitor large-scale forest composition patterns across the decades.
“We hope that this model can help forest managers track conifer composition over time and help them adapt their management goals,” Donnini says. “The remote sensing aspect is useful, because it shows that a relatively simple satellite-based model can monitor changes over large areas accurately.”
This study received funding from the Fonds de recherche du Québec – Nature et technologies and the Natural Sciences and Engineering Research Council of Canada.
Read the cited paper: “ Tracking conifer composition changes: a ground and satellite based assessment of Quebec’s forests over three decades .”
Journal of Forestry Research
Data/statistical analysis
Not applicable
Tracking conifer composition change: a ground and satellite based assessment of Quebec’s forests over three decades
18-Apr-2026
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