Microbial controls on methane fluxes from a polygonal tundra of the Lena Delta, Siberia

• Published in: Permafrost and Periglacial Processes
• Main Authors: Wagner, D., Kobabe, S., Pfeiffer, E.‐M., Hubberten, H.‐W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2003
• Subjects: Arctic; lena delta; permafrost; Permafrost and Periglacial Processes; Tundra; Siberia
• Online Access: http://dx.doi.org/10.1002/ppp.443; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fppp.443; https://onlinelibrary.wiley.com/doi/pdf/10.1002/ppp.443

Abstract Permafrost soils of high‐latitude wetlands are an important source of atmospheric methane. In order to improve our understanding of the large seasonal fluctuations of trace gases, we measured the CH 4 fluxes as well as the fundamental processes of CH 4 production and CH 4 oxidation under in situ conditions in a typical polygon tundra in the Lena Delta, Siberia. Net CH 4 fluxes were measured from the polygon depression and from the polygon rim from the end of May to the beginning of September 1999. The mean flux rate of the depression was 53.2 ± 8.7 mg CH 4 m −2 d −1 with maximum in mid‐July (100–120 mg CH 4 m −2 d −1 ), whereas the mean flux rate of the dryer rim part of the polygon was 4.7 ± 2.5 CH 4 m −2 d −1 . The microbial CH 4 production and oxidation showed significant differences during the vegetation period. The CH 4 production in the upper soil horizon of the polygon depression was about 10 times higher (38.9 ± 2.9 nmol CH 4 h −1 g −1 ) in July than in August (4.7 ± 1.3 nmol CH 4 h −1 g −1 ). The CH 4 oxidation behaved exactly in reverse: the oxidation rate of the upper soil horizon was low (1.9 ± 0.3 nmol CH 4 h −1 g −1 ) in July compared to the activity in August (max. 7.0 ± 1.3 nmol CH 4 h −1 g −1 ). The results indicated clearly an interaction between the microbiological processes with the observed seasonal CH 4 fluctuations. However, the CH 4 production is primarily substrate dependent, while the oxidation is dependent on the availability of oxygen. The temperature plays only a minor role in both processes, probably because the organisms are adapted to extreme temperature conditions of the permafrost. For the understanding of the carbon dynamics in permafrost soils, a differentiated small‐scale view of the microbiological processes and the associated modes of CH 4 fluxes is necessary, especially at key locations such as the Siberian Arctic. Copyright © 2003 John Wiley & Sons, Ltd.