Measuring and modelling carbon storage in Quebec boreal black spruce ecosystems under varying fire regimes

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Canada lacks critical information about boreal ecosystem carbon dynamics and carbon stability in boreal forest soils. This information is important to modelling efforts to predict responses of ecosystems to climate change and feedbacks that may impinge on the global carbon cycle. Our multidisciplinary team will measure key elements of carbon dynamics in boreal forests and subsequently integrate this information via a modelling exercise. Recent information from climate models suggests that the wide belt of black spruce forest that covers that Canadian Shield may be subject to more frequent wildfire disturbance in the future. Fires may also be less intense than they have been in the past. We will examine the relationship between fire severity and the quantity and quality of charcoal produced; the process of charring stabilizes carbon in a more recalcitrant form. We will also investigate the fate of charcoal in the soil profile, i.e. where and how it is stored, and how the material of origin (for example moss, or wood) might affect storage. We will measure input rates of carbon to the soil via burnt tree boles that gradually weather and fall to the soil to contribute to organic matter. Fire severity effects on early response of the understory (mosses, herbs and shrubs) will be evaluated and integrated into the modelling exercise. We will identify abiotic factors that may interact with severity to control plant succession, productivity (biomass) and therefore carbon storage. Finally, we will examine how black spruce seedlings regenerate under different fire severities. The emphasis will be on interaction of regeneration with other components of the ecosystem. For example, a lower production of charcoal with less severe fires may be beneficial to the ericad shrubs, since charcoal has been shown to absorb phenolic compounds that interfere with the nutrition and growth of conifers. We will work directly with our industrial partners to evaluate their current strategy of salvage of burnt wood, followed generally by site preparation and planting. We need to understand more about the impacts of both salvage (potential impacts on regeneration of both the seedlings and vegetation), as well as the success of replanting burnt sites after site preparation.