Autochamber measurements of Net Ecosystem (CO2) Exchange at a subarctic mire in Northern Sweden

Permafrost stores 50% of the global soil organic carbon. Increasing climate temperatures in the arctic region have given rise to permafrost thaw, exposing once stable organic carbon to decomposition, and potentially altering the global carbon budget. In this study, we present a secondary data analysis of high frequency net ecosystem (CO2) exchange measurements made using a quantum cascade laser spectrometer connected to a nine member autochamber system positioned in the three dominant vegetation communities at Stordalen Mire in Northern Sweden (68° 21'N, 18° 49'E). Over DOY 121 - 260 during the year 2013, the magnitude of net ecosystem (CO2) exchanged followed the moisture gradient with increasing CO2 uptake from the dry Palsa site (- 0.3 ± 1.6 mg C m-2 h-1), to the wet intermediate melt feature with Sphagnum spp. (- 22.1 ± 0.9 mg C m-2 h-1), to the fully wet Eriophorum spp. site (- 49.9 ± 4.2 mg C m-2 h-1), with highest uptake occurring in the fully thawed Eriophorum/ Sphagnum (Ch. 9) collar (- 87.2 ± 6.0 mg C m-2 h-1) (overall mean ±1 SE, n = 1267, 2334, 1211, 772). All mean fluxes were statistically different from each other (p < 0.0001). At all sites, PAR was the best environmental predictor of NEE. Although increased warming has resulted in permafrost thaw, any possible loss of old carbon in the form of CO2 from thawing or thawed sites was more than offset by a greater net uptake of CO2 occurring in the wetter sites.