Grant: Discovery Grants Program - Individual

Wildfire and drought impact forest ecosystems globally and are becoming more extreme and widespread. The ecological resilience of forests is challenged by rapidly changing climate conditions and land management practices over the past century. The decline of wildfire since ~1900 in montane forests of western North America has led to denser forests and more forest fuels. In British Columbia, wildfires in 2017, 2018, and 2021 burned 3.4 million ha (3.6% of British Columbia). Burning mainly in interior dry forests, these intense and expansive wildfires caused high-severity fire effects, even in forests historically maintained by low-severity surface fires (e.g., forest-grassland ecotones). In addition to wildfire, drought is more common. For example, in 2021 western Canada experienced a `heat dome' that lasted for seven days with many areas reaching record breaking temperatures up to 49.6°C. This increase in wildfire severity and drought prompts four questions: Are wildfires causing more severe ecological effects? Is forest resilience to wildfire and drought changing? How do wildfire and drought interact to influence forest regeneration? Can forest and fire management practices better promote forest resilience? In British Columbia, forest-grassland ecotones border the largest areas of native grasslands (662,872 ha) in western North America, contain valuable timber resources, and natural habitat. Vegetation species growing in ecotone ecosystems are in niche margin habitats and are particularly vulnerable to change. Over the next five years, my research team and I will carry out a series of related ecological projects that will rely on information from tree-ring datasets and blend historical and contemporary perspectives to characterize resilience of forest-grassland ecotones to wildfire and drought. First, we extend our wildfire history reconstructions west of the Fraser River and into ecotone forests. Second, we will determine if the moisture sensitivity and drought responses of ecotone trees is changing over time. Third, we will describe the patterns in vegetation regeneration following recent and repeat wildfires, including the growth responses of post-fire seedlings to drought. One PhD, four master's, and five undergraduate students will receive training through this program. Considering projected climate change and observed increases in wildfire activity, wildfire will be a ubiquitous agent of change in forest-grassland ecotones. This work will determine if wildfire regimes and tree drought responses in ecotone forests are disrupted from their historical character (natural range of variability), and document wildfire and drought impacts on ecotone forests. Canada faces increasing challenges from wildfire, this research program will lead to better informed forest and fire management practices to enhance resilience in Canada's forests.