Spatial variability in carbon exchange processes within wet sedge meadows in the Canadian High Arctic
at : Mar 11, 2021 16:24:02  (view:458)

Spatial variability in carbon exchange processes within wet sedge meadows in the Canadian High Arctic

Claire M. WRIGHT, Amy C. BLASER, Paul M. TREITZ, Neal A. SCOTT*

Department of Geography and Planning, Queen’s University, Kingston, Ontario, Canada, K7L 3N6

Corresponding author, E-mail: neal.scott@queensu.ca

Abstract Wet sedge meadows are the most productive plant communities in the High Arctic. However, the controls on carbon dynamics within wet sedge communities – and the scale at which they operate – are poorly understood. Here, the factors controlling carbon dioxide (CO2) exchange of wet sedge meadows experiencing different moisture regimes are examined. Environmental data are used to create predictive models of CO2 exchange on multiple temporal scales. Automated CO2 chamber systems recorded carbon fluxes at 30-min intervals at wet sedge sites in the Canadian High Arctic from June to August in 2014 and 2015. Static chambers were also deployed over a larger spatial extent in 2014.

Our results show that wet sedge communities were strong carbon sinks during the growing season (−42.46 g C·m−2 and −72.06 g C m−2 for 2014 and 2015, respectively). Carbon exchange rates in wetter and drier areas within wet sedge meadows differed significantly (Wilcoxon, p < 0.001), suggesting that soil moisture regimes within vegetation types influence net carbon balance. Random Forest models were able to predict a significant amount of the variability in carbon flux rates over time (R2 = 0.46 to 0.90). The model showed that the drivers of CO2 exchange in these communities are dependent on temporal scale. Variable moisture regimes were shown to indirectly influence carbon fluxes given that they exhibit different vegetation and temperature-response characteristics. We suggest that the response of a single vegetation type to environmental changes may vary depending on microenvironment variability within that community.

Keywords  High Arctic, carbon dioxide exchange, wet sedge, soil moisture