DOI: 10.5593/sgem2017/32/S13.034


S. Evgrafova, O. Novikov, M. Meteleva, G. Guggenberger
Monday 11 September 2017 by Libadmin2017

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgem.org, SGEM2017 Conference Proceedings, ISBN 978-619-7408-05-8 / ISSN 1314-2704, 29 June - 5 July, 2017, Vol. 17, Issue 32, 257-264 pp, DOI: 10.5593/sgem2017/32/S13.034


We aimed at identifying the microbial response and associated release of CO2 and CH4 in/from thawing soil that has been permanently frozen. For that we performed an in situ field-based incubation experiment in a rim of ice-wedge polygon on Samoylov island, Lena Delta, Russia (72°22’N, 126°28’E). Frozen "buried’ organic matter were taken from eroded Lena river bank and transferred to the soil surface in a rim of ice-wedge polygon. The principle includes that formerly frozen soil is moved to the active layer, but still residing in the subsoil in order to mimic cryoturbation processes. The mean seasonal methane efflux from soil surface with the transplaced permafrost soil, as measured in the vegetation period after experiment set up, was 0.55±0.07 mg CH4 m-2 h-1; whereas the mean seasonal methane efflux from plots without buried organic material (i.e., disturbance control) was 0.50±0.02 mg CH4 m-2 h-1. Hence, differences were minor. CO2 emission measured by dark chambers did not differ in magnitude during 4 weeks from the beginning of the vegetation period, and then was approximately 1.5 times larger in plots containing organic material. The release of CO2 from soil was mainly responding to soil temperature, as the Pearson’s coefficient for correlation between heterotrophic respiration rate and soil and air temperature was r=0.63, r=0.38, respectively. We conclude that the heterotrophic part of microbial community needs some period for adaptation to the chemical properties of the introduced organic matter (approximately 3-4 weeks). Consequently, due to the short vegetation period in this ecosystem we expect that the acceleration of carbon release is possibly not pronounced.

Keywords: permafrost-affected soils, "buried’ organic matter, field-based incubation experiment, CO2, CH4

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