Amid Ontario’s unprecedented wildfire season, recent research from McGill University reveals the protective role of aspen trees in fire prevention. Flavie Pelletier, the lead author of the study and a PhD graduate, highlighted the resilience of aspen trees to wildfires, despite their thin bark that can ignite quickly.

Through a study of satellite imagery of Canada’s boreal forest pre and post wildfires, Pelletier and her team observed that extensive patches of aspen can effectively impede the spread of wildfires. These images indicated a prevalence of large aspen patches at the edges of burnt areas.

Exploring the reasons behind aspen’s fire-retardant properties, Pelletier mentioned the higher moisture content in aspen trees compared to coniferous species. Additionally, the positioning of aspen leaves higher on the trunk reduces the likelihood of ground fires spreading quickly compared to coniferous trees like spruce and pine.

Despite the beneficial role of aspen in fire prevention, Pelletier warned of a prevailing “war against aspen” in commercial forests, where forestry companies in Ontario routinely use herbicides, primarily glyphosate, to eliminate broadleaf vegetation competing with commercially valuable coniferous trees. This practice, according to Pelletier, may elevate the long-term fire risk by diminishing aspen populations.

Fred Pinto, a forestry expert, acknowledged the return of broadleaf vegetation like aspen following glyphosate spraying, which could take several years. He emphasized that a small portion of Ontario’s boreal forest is harvested annually, with many current wildfires occurring in unsprayed and unharvested remote areas.

Regarding concerns about the toxicity of wildfire smoke from glyphosate-treated forests, Pinto suggested that any chemical presence would be minimal and likely vaporized by the intense heat of wildfires. He noted that measuring glyphosate residues in the air post-wildfire would be challenging due to their negligible concentration compared to the overall biomass.