Carbon sequestration in managed forest and grassland ecosystems in Western Canada

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There is a general scientific consensus that climate change is occurring and that it is partly induced by human activity as it is caused by an increase in greenhouse gases in the atmosphere. The increase of the most notorious greenhouse gas, carbon dioxide, is mainly due to the burning of fossil fuels and land-use change. Terrestrial ecosystems have the potential to curb these emissions by sequestering large amounts of carbon into their biomass or the soil component. The use of terrestrial ecosystems as a mitigation measure requires, however, further quantitative evidence. My research program examines the influence of climate variability, natural and anthropogenic disturbances, as well as management practices on the carbon sequestration of forest and grassland ecosystems. I use a bottom-up approach, using carbon dioxide flux chamber measurements of photosynthesis and respiration, to partition and scale up component fluxes of carbon dioxide to the ecosystem level. By quantifying the contribution of the soil, grassland and forest-floor vegetation, as well as understory and overstory shrub and tree components, I quantify the sink or source strength of these ecosystems and I assess their responses to different management practices such as nitrogen fertilization and cattle grazing. The results that are obtained through my research program significantly increase our understanding of the role of forest and grassland ecosystems in the global carbon cycle and how they respond to different management practices and climate change. They help in developing and parameterizing forest and grassland productivity models needed to better manage natural resources and help Canada increase carbon sequestration in its managed ecosystems. They also allow Canada to develop strategies to meet its Kyoto commitments.