When Jennifer Donnini examined nearly 1,800 forest plots scattered across Quebec, she discovered something quietly remarkable: the conifers are returning. After three decades of decline, the shade-tolerant balsam firs that once blanketed the region are creeping back through the canopy, slowly reclaiming their place in forests that had been taken over by faster-growing birches and aspens.
The recovery tells a story written in the language of ecological time. A spruce budworm outbreak that ravaged Quebec's forests from 1972 to 1986 devastated the conifer population across large swaths of the province. In the chaos and light that followed, deciduous species thrived, their fast growth filling the gaps left by the dying firs. But nature rarely moves in straight lines. Over the decades since that outbreak ended, the shade-tolerant balsam firs waited patiently in the understory, and as the broadleaf trees matured and grew denser, the firs began their slow ascent back to dominance.
The finding, published in the Journal of Forestry Research and led by Donnini, a Ph.D. candidate in the Department of Geography, Planning and Environment at Concordia University, matters because forests are not simply trees—they are homes. The balance between conifers and deciduous species shapes wildlife habitat, regeneration patterns, and how a forest withstands insects, fire, or harvesting. Understanding these shifts is essential for forest managers trying to sustain Quebec's woodlands.
Almost half of all the plots studied showed an increase in conifer composition between 1985 and 2021. The gains were strongest in mixed forests, where more than 60% of plots recorded increases in conifers. Meanwhile, deciduous species like paper birch, trembling aspen, and sugar maple saw their relative importance decline. The researchers found virtually no evidence of the reverse trend—forests are not shifting back toward deciduous dominance.
What makes this study particularly innovative is how Donnini and her colleagues tracked these changes. They combined nearly four decades of ground-based forest inventory data from the Quebec government with a new satellite-based model trained using artificial intelligence. The system used only four variables from summer and winter satellite imagery, making it straightforward enough to scale across vast regions. While the satellite model proved less precise at detecting fine-scale changes within individual plots, it successfully captured the broad regional trends that ground crews documented in the field.
The researchers believe the conifer rebound reflects a natural cycle rather than an unusual shift. Forest tent caterpillar outbreaks, which target hardwoods like birch and aspen, may have also created favorable conditions for fir regeneration, they suggest. As Donnini explains, balsam fir's shade tolerance is its greatest strength in this long game—it can survive in dim understory conditions and wait for its moment to expand.
The implications reach beyond academic interest. If these satellite models can reliably monitor conifer composition across large areas over decades, forest managers gain a tool to adapt their strategies to the changing landscape. Quebec's forests are not static artifacts to be preserved in amber, but dynamic systems responding to disturbance, recovery, and the relentless patience of shade-tolerant trees reclaiming what they lost.