SRA

Around 1700 Gt carbon are stored in the Northern latitude permafrost regions (Schuur et al, BioScience 2008). This is more than double the size of the atmospheric carbon pool but the estimates are still quite uncertain and might be even higher. It is however estimated that 25 percent of this large carbon pool in Arctic soils will be lost by the end of the 21st century and will be released to the atmosphere as CO2 (Gruber et al., 2004). The subduction of organic-rich material from the surface to deeper layers caused by repeated freezing and thawing of the active layer during Arctic summer is assumed to be a major mechanism of carbon storage in the Arctic. These cryoturbations are spatially widely distributed and store high amounts of soil organic carbon (SOC). Decomposition of recent cryoturbated carbon is strongly retarded thereby essentially taking out this fraction of SOC from the current carbon cycle. Todays primary concern and research focus is the vulnerability of cryoturbated SOC due to global warming which is predicted to lead to intensified decomposition and elevated greenhouse gas emissions. Here we present a study that aims to provide a comprehensive picture of the microbial community structure of permafrost-affected and cryoturbated soils of different Northern latitude permafrost regions in Siberia and Greenland. For this purpose, soil samples were collected in northeast Siberia in a transect along the upper Kolyma river, and in the Zackenberg region, Greenland. The sampling scheme covered several bioclimatic subzones and vegetation types. We are currently analysing data retrieved from SSU amplicon sequencing, the quantification of several functional groups involved in carbon cycling and physico-chemical analyses in order to predict potential microbial regulators in SOC storage. This study is part of the multinational CryoCARB project (for further information, see: www.cryocarb.net).