Warming of subarctic tundra increases emissions of all three important greenhouse gases – carbon dioxide, methane, and nitrous oxide

• Published in: Global Change Biology
• Main Authors: Voigt, Carolina, Lamprecht, Richard E., Marushchak, Maija E., Lind, Saara E., Novakovskiy, Alexander, Aurela, Mika, Martikainen, Pertti J., Biasi, Christina
• Other Authors: Suomen Akatemia, United Engineering Foundation, European Cooperation in Science and Technology
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2016
• Subjects: Arctic; Climate change; permafrost; Subarctic; Tundra
• Online Access: http://dx.doi.org/10.1111/gcb.13563; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fgcb.13563; https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.13563

Abstract Rapidly rising temperatures in the Arctic might cause a greater release of greenhouse gases ( GHG s) to the atmosphere. To study the effect of warming on GHG dynamics, we deployed open‐top chambers in a subarctic tundra site in Northeast European Russia. We determined carbon dioxide ( CO 2 ), methane ( CH 4 ), and nitrous oxide (N 2 O) fluxes as well as the concentration of those gases, inorganic nitrogen (N) and dissolved organic carbon ( DOC ) along the soil profile. Studied tundra surfaces ranged from mineral to organic soils and from vegetated to unvegetated areas. As a result of air warming, the seasonal GHG budget of the vegetated tundra surfaces shifted from a GHG sink of −300 to −198 g CO 2 –eq m −2 to a source of 105 to 144 g CO 2 –eq m −2 . At bare peat surfaces, we observed increased release of all three GHG s. While the positive warming response was dominated by CO 2 , we provide here the first in situ evidence of increasing N 2 O emissions from tundra soils with warming. Warming promoted N 2 O release not only from bare peat, previously identified as a strong N 2 O source, but also from the abundant, vegetated peat surfaces that do not emit N 2 O under present climate. At these surfaces, elevated temperatures had an adverse effect on plant growth, resulting in lower plant N uptake and, consequently, better N availability for soil microbes. Although the warming was limited to the soil surface and did not alter thaw depth, it increased concentrations of DOC , CO 2, and CH 4 in the soil down to the permafrost table. This can be attributed to downward DOC leaching, fueling microbial activity at depth. Taken together, our results emphasize the tight linkages between plant and soil processes, and different soil layers, which need to be taken into account when predicting the climate change feedback of the Arctic.