Examining the offsetting potential of vegetation changes on wildfires in managed forests of boreal Canada

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The 20th century was a pivotal period at high northern latitudes as it marked the onset of a rapid climatic warming associated with major anthropogenic changes in global atmospheric composition. Prominent effects resulting from the atmospheric changes include more wildfire activity in northern Canadian boreal regions from the mid-20th to the early 21st centuries. The phenomenon of enhanced wildfire activity is projected to continue throughout this century, and this across much larger areas of Canada, as atmospheric greenhouse gases attain unprecedented levels. To offset the increasing wildfire risks in managed forests, it was suggested that manipulative vegetation treatments be applied in dense coniferous landscapes. The introduction of a broadleaf component as strategic barriers could decrease the intensity and rate of spread of wildfires, improve suppression effectiveness, and reduce wildfire impacts. Our work in the eastern Canadian boreal forest clearly shows the important function for broadleaf vegetation in reducing levels of wildfire activity in a warmer climate. Nevertheless, important questions remain relative to the magnitude of vegetation composition changes needed to attain the wildfire management objectives (e.g. relative abundance/biomass of species and size of the managed areas), and the existence of potential constraints on the success of species establishment (e.g. nutrient limitations; unfavourable climate conditions, etc). Additionally, this management option will only work if the biotic feedback is strong enough for modulating the influence of future climate change on wildfire: under excessive droughts, the relative importance of vegetation diminishes since stands can achieve the threshold required to permit large wildfire development. The objectives of this research are to explore the regional stand attribute settings (species and stand demographics) that allow a modulation of wildfire frequency trajectories. This will be done by innovative paring of a dynamic global vegetation model (DGVM) with paleoecological data (pollen, plant macro-remains, charcoal particles). The use of paleoecological data is intended to provide a ground- based validation of model assumptions. The hypothesis to be tested is that northern forest areas are vulnerable to high wildfire activity brought about with climate warming, and this vulnerability is dependant upon the dominance of coniferous species in landscapes. Specifically, the work will pursue the parameterization and validation of a DGVM for application in managed boreal forests of Canada, determine the impact, exposure and sensitivity of these forests to fires under a changing climate at different temporal and spatial scales, and 3. Describe the potential impacts resulting from modifications of vegetation composition and structure, on future fire activity and evaluate the pro and cons of various vegetation modification scenarios. Fire suppression costs over the last decade in Canada have ranged from about $500 million to $1 billion a year, while property losses during 2002-2011 averaged $3.5 million annually. The economic benefits derived from minimizing the impacts of fire disturbances are evident. This project will provide science based information and technology that Canadian jurisdictions (e.g. provinces, territories) will be able to use for making informed decisions and policies concerning wildfires. Changes in fire activity and the impacts of fire on economic, environmental and social considerations, as well as risk mitigation options to protect human communities and other values at risk, will be better assessed.