When boreal forests burn again and again

Increasingly severe and frequent wildfires, exacerbated by rising temperatures and drought due to climate change, are transforming Canada’s boreal forest ecosystem.

Ellen Whitman, a forest-fire research scientist, observed a drastic shift in the southern Northwest Territories after consecutive fires within 15 years. The first fire wiped out older coniferous trees, and the second killed young conifers that couldn’t mature in time to regenerate. This left space for grasses, shrubs, and deciduous trees to take over, transforming the landscape into a savannah-like environment.

Wildfires have burned over 15.4 million hectares in Canada this year, breaking previous records. The intensifying wildfires could hinder the recovery of coniferous forests, causing them to be replaced by leafy trees, shrubs, and grasslands. This transformation could impact wildlife and ecosystems.

Drought and warming temperatures from climate change are creating conditions that make wildfires more frequent, larger, and faster-spreading. These changes are driving long-term shifts in the boreal forest. Historically, fire played a crucial role in renewing the boreal forest, but the altered fire regime is causing lasting changes in forest structure and function.

Researchers have observed a doubling of large fires in the boreal forest between 1959 and 2015. Fires occurring within short intervals are becoming more common, hampering regeneration. Over 6% of Canada’s boreal forest experienced reburning within 30 years from 2014 to 2021. The trend of reburning is growing, threatening forest recovery.

As fires become more frequent, areas that have burned before are expanding, leading to changes in tree composition. Young, managed forests are also burning, hindering regeneration. Climate change-driven shifts are altering bird populations, favoring species adapted to changing forests while endangering those reliant on old coniferous habitats.

Solutions to combat these changes include rethinking logging practices to preserve mature trees for seed sources, using controlled burns to manage fire regimes, and protecting peatlands to buffer against fires. Adapting and planting drought-resistant tree species may also become necessary. While the boreal forest’s transformation won’t happen overnight, it’s a persistent trend requiring attention and action.

https://www.theglobeandmail.com/canada/article-as-canadas-boreal-forests-burn-again-and-again-they-wont-grow-back-the/