Carolina Voigt
Postdoctoral fellow
Department of geography
University of Montreal

Supervised by:

Oliver Sonnentag (Regular member)

Research project description

Linking above- and belowground greenhouse gas dynamics in the arctic-boreal region of Canada

Introduction: Projected temperature increase will be most pronounced in the Arctic-Boreal Region (ABR) of Canada, promoting the accelerated release of carbon and nitrogen stocks currently immobilized in permafrost. Yet, we severely lack understanding on the complex biogeochemical functioning of these heterogeneous and remote ecosystems. Greenhouse gas (GHG) production in Arctic and boreal soils is intricately bound to carbon and nutrient availability in these generally nutrient-limited systems, where plants and microbes compete actively for available nutrients. Thus, whether these northern ecosystems act as a source or sink of GHGs depends on soil nutrient availability, plant-soil interactions and interlinkages between the carbon and nutrient cycles. However, studies combining aboveground GHG flux measurements with belowground process studies are scarce in these remote and not easily accessible regions, and pose a challenge due to the spatial heterogeneity of the ABR landscape. Objectives: The main objective of my study is to explore the above- and belowground links between the carbon and nitrogen cycle in the ABR region. Specifically, I will monitor fluxes of the GHG carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), and link these observations with process-based measurements of soil GHG and nutrient dynamics. Study sites: GHG dynamics will be studied at two sites in the Northwest Territories: Trail Valley Creek (68°44’ N, 133°29’ W), an arctic tundra site located just north of the treeline on continuous permafrost, and Scotty Creek (61°18’ N, 121°18’ W), a rapidly thawing peatland landscape on sporadic permafrost in the boreal zone. Material and methods: My study aims to capture the spatial and temporal variability of GHG fluxes (CO2, CH4, and N2O) from individual land cover types (upland tundra surfaces, polygonal tundra areas, lakes, streams, wetlands) using manual and also automated chambers – a challenging and so far unique measurement tool this far north in the Canadian Arctic. These flux measurements aim to capture the high temporal and spatial resolution of GHG dynamics, and are complemented with a detailed array of measurements of underlying biogeochemical processes in the soil profile, among which soil nutrient, GHG and oxygen dynamics will be key components to link observed aboveground GHG fluxes to belowground processes. Expected results: Exploring above- and belowground links between carbon and nitrogen cycles in high-latitude ecosystems will considerably advance our understanding of the climate feedback of ecosystems in the ABR region. Specifically, I expect GHG fluxes to display a high spatial and temporal variability across the heterogeneous landscape, depending on soil type, moisture conditions, and vegetation composition.

Research Site Coordinates

Scientific Communications

Mavrovic, A., Sonnentag, O., Lemmetyinen, J., Voigt, C., Rutter, N., Mann, P., Sylvain, J.-D., Roy, A.R., 2023. Environmental controls of winter soil carbon dioxide fluxes in boreal and tundra environments. <strong>Biogeosciences</strong>, 20(24): 5087-5108. DOI: <a href="" target="_blank">10.5194/bg-20-5087-2023</a>.

Voigt, C., Marushchak, M.E., Abbott, B.W., Biasi, C., Elberling, B., Siciliano, S.D., Sonnentag, O., Stewart, K.J., Yang, Y., Martikainen, P.J., 2020. Nitrous oxide emissions from permafrost-affected soils. <strong>Nature Reviews Earth &amp; Environment</strong>, 1: 420-434. DOI: <a href="" target="_blank">10.1038/s43017-020-0063-9</a>.

Voigt, C., van Delden, L., Marushchak, M.E., Biasi, C., Abbott, B.W., Elberling, B., Siciliano, S.D., Sonnentag, O., Stewart, K.J., Yang, Y., Martikainen, P.J., 2020. Nitrous oxide fluxes from permafrost regions. DOI: <a href="" target="_blank">10.1594/PANGAEA.919217</a>.

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