Forest resilience in the 21st century: Adapting to altered fire regimes and climate change

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Wildfire is the most important natural disturbance agent affecting global forests. Changes to fire regimes, triggered by subtle changes in climate and human impacts, have potential major impacts on ecosystems. The current rate and magnitude of climate change have the potential to jeopardize ecological resilience so that disturbed ecosystems are unable to recover. Understanding fire regimes and their drivers is essential to adapt, given the potential consequences of climate change. Worldwide, intense and fast-moving megafires have burned with severe social, economic, and ecological impacts. The record-breaking wildfires of 2017 in British Columbia burned 1.2 million hectares, mostly in montane forests. These fast-moving, intense fires had high-severity effects, even in montane forests with strong evidence of past low-severity surface fire regimes. These extreme wildfires incite three ecological questions:    Have fire regimes been altered beyond historical limits?    Is forest resilience to fire compromised?    How do we adapt management to improve forest resilience? My research shows that fire regimes in montane forests differs from those in boreal forests in meaningful ways. Mixed-severity fire regimes include frequent surface fires and periodic crown fires and historically dominated montane forests in British Columbia and the foothills of Alberta. Improved understanding of the dynamics and drivers of mixed-severity fire regimes is urgently needed to assure the resilience of these forests. Over the next 5 years my research team and I will complete a series of inter-related research projects: Phase 1 will expand our network of fire history reconstructions into the driest forests in BC. We will use multiple lines of tree-ring evidence to compare fire history among these study areas. We will determine if changes to historic fire regimes are pervasive among climatic regions and the consequences for forest composition and structure. Phase 2 combines western science with Indigenous knowledge for a comprehensive understanding of cultural fire and its ecological effects. Phase 3 addresses the consequences of eliminating surface fires from forest stands and landscapes. Combining fieldwork and air photograph analysis with fire behaviour modelling, we will quantify the amount of fuels that have built up and the probability of forests to burn as high intensity crown fires. The final phase of this research assesses how climate change exacerbates these problems. Three PhD, 3 MSc and c.14 undergraduate students will be integrally involved with this research. Ultimately, we will generate new knowledge on the drivers of historical fire regimes, the degree to which they have changed, and the consequences to forest resilience. Our work will help prioritize areas for fuels mitigation and ecological restoration. It also provides a much-needed baseline to ensure adaptive management is effective at improving forest resilience to climate change.