Sources and ages of soil respiration, Toolik Lake, AK, 2019-2022

Snow cover plays an important role in the energy budget, biogeochemistry, and ecology of Arctic. Deeper snow, associated with changes in climate, may lead to warming of permafrost and greater microbial processing during winter, the season that last for more than ⅔ of the year in the north. Here, we investigate how 25 years of experimental snow addition in Arctic Alaska has impacted the sources and ages of microbial respiration. To measure the in-situ sources of microbial respiration, we installed 24 access wells (diffusive silicone inlet attached to steel well, Pedron et al. (2021)) in June 2019 for soil CO2 sampling within the Control and +Snow zones. Access well inlet depths were chosen to sample the organic (-20 centimeters (cm)) and mineral (-50 cm) horizons as well as the top of the permafrost table (-80 cm, n=4 per depth and zone). Samples were collected from June 2019 to April 2021 over periods of 5-18 weeks using exchangeable molecular sieve (MS) traps (Pedron et al. 2021).