Tree-ring research in the eastern Canadian taiga

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The boreal forest is by far the most important biome of Canada. Boreal vegetation is important for our industry and our way of living. However, the boreal forest is expected to warm rapidly and experience more fires, thus threatening the services it provides. This research aims to use tree-rings to understand the dynamics of the Eastern Canadian taiga under the dominant influence of fire disturbance and climate change and to reconstruct past climate change from ancient subfossil trees. The first objective is to reconstruct the empirical fire interval frequency distribution to quantify how much the North American boreal forest can absorb the fire activity and protect itself by limiting the prevalence of deleterious short fire intervals. Because more severe fire weather conditions are anticipated with climate change, the second objective is to evaluate how this self-protection may collapse due to more severe fires in the future. The third objective is to use X-ray-based latewood density measurements from subfossil trees sampled in lake sediments to develop a temperature reconstruction covering the complete Common Era in the North American boreal forest. This will provide context to evaluate the importance of the current warming trend and will be a long-awaited addition to improve large-scale (e.g. Northern hemisphere) climate reconstructions by international teams. The fourth objective is to quantify the negative impact of volcanism on black spruce productivity across the Eastern Canadian boreal forest during the last millenium. Although tree rings have been used to reconstruct the climatic impact of volcanoes, the impact of volcanoes on tree productivity is unknown, notably for black spruce, the most important tree species in the North American boreal forest and one of the most successful plant species on Earth in terms of standing biomass. The last objective is to share our complete millennial tree-ring database, including all metadata. Overall, this research will contribute important findings and data to anticipate and manage upcoming climate changes and associated forest trajectories.