Understory CO2emissions in tussock tundra of Imnavait Creek, Alaska

Abstract:

Soil carbon (CO₂) emission is sensitive to changes in temperature, moisture, and the organic carbon that is stored in tundra soils of northern hemisphere. CO₂ emission can thereby be affected by recent Arctic climate change and warming. Here, we have conducted soil CO₂ efflux measurements with forced diffusion chambers in the tussock tundra ecosystem of North Slope, Alaska, from August 2018 to June 2019, in order to assess the contribution of tussock and inter-tussock carbon to ecosystem respiration (R_eco) within the footprint of CO₂ measurements made from an eddy covariance tower and where permafrost temperatures have been increasing since 2005 (Euskirchen et al., 2017). As the results, the annual average ± standard deviation CO₂ emissions from the chambers were 0.68 ± 0.66 and 0.52 ± 0.42 µmol m^-2 s^-1in tussock and inter-tussock (Sphagnum spp) during the same period. R_eco from the eddy covariance measurement was 0.34 ± 0.28 µmol m^-2 s^-1, respectively. Non-growing season average carbon emissions were 0.47 ± 0.54, 0.31 ± 0.25, and 0.22 ± 0.17 µmol m^-2 s^-1in tussock, inter-tussock, and R_eco, respectively. This non-growing period was from October 12, 2018 to May 17, 2019, based on the lingering snow by interval camera measurement. Understory CO₂ contributions in tussock and inter-tussock to R_eco were 200 and 162 % in growing season and 215 and 142 % in non-growing season, respectively. Further, CO₂ emissions in tussock during growing and non-growing seasons were 1.23- and 1.52-fold higher than inter-tussock, respectively. This understory tussock tundra is acting as source of atmospheric CO₂ during our period of study in Arctic tundra ecosystems.

Reference

Euskirchen ES, Bret-Harte MS, Shaver GR, Edgar CW, and Romanovsky VE (2017) Long-term release of carbon dioxide from Arctic tundra ecosystems in Alaska, Ecosystems, 20: 960–974, DOI: 10.1007/s10021-016-0085-9.