University of Alberta
Wildfire is the dominant stand-renewing disturbance in the northwestern Canadian boreal forest. Fires burn extensive areas in Canada, disturbing an average of 1.96 Mha yr−1, primarily in the boreal zone. Fires generally occur every ~30 – > 200 years in this region, due in part to a lack of fuel that allows young stands to resist reburning. Boreal understory plants and trees are adapted to stand-renewing wildfire through mechanisms such as serotiny, seed banking, and resprouting from roots and rhizomes of top-killed individuals. Such adaptations confer resilience to boreal forests, and post-fire vegetation communities generally resemble the pre-fire ones, following a stand self-replacement trajectory. Recently, the area burned, average fire size, and fire season length in northwestern Canada have increased. Severe fire weather has enabled reburning of young forests at very short intervals (sometimes ≤ 10 years between fires). Such changes in fire regime appear to be driven by anthropogenic climate change and increasingly severe fire weather. Furthermore, increasing moisture stress is implicated in simultaneous increases in fire activity, and worsening conditions for post-fire establishment of trees. Shifts in fire regime characteristics, such as burn severity and fire-free interval may lead to changes in vegetation composition following fire, thwarting stand self-replacement expectations.
Whitman, E. 2019. Burn severity and fire history in the northwestern Canadian boreal forest: drivers and ecological outcomes. University of Alberta. 114 p. [Dissertation]