title: Input of easily available organic C and N stimulates microbial decomposition of soil organic matter in arctic permafrost soil.
abstract: Rising temperatures in the Arctic can affect soil organic matter (SOM) decomposition directly and indirectly, by increasing plant primary production and thus the allocation of plant-derived organic compounds into the soil. Such compounds, for example root exudates or decaying fine roots, are easily available for microorganisms, and can alter the decomposition of older SOM ("priming effect"). We here report on a SOM priming experiment in the active layer of a permafrost soil from the central Siberian Arctic, comparing responses of organic topsoil, mineral subsoil, and cryoturbated subsoil material (i.e., poorly decomposed topsoil material subducted into the subsoil by freeze-thaw processes) to additions of13C-labeled glucose, cellulose, a mixture of amino acids, and protein (added at levels corresponding to approximately 1% of soil organic carbon). SOM decomposition in the topsoil was barely affected by higher availability of organic compounds, whereas SOM decomposition in both subsoil horizons responded strongly. In the mineral subsoil, SOM decomposition increased by a factor of two to three after any substrate addition (glucose, cellulose, amino acids, protein), suggesting that the microbial decomposer community was limited in energy to break down more complex components of SOM. In the cryoturbated horizon, SOM decomposition increased by a factor of two after addition of amino acids or protein, but was not significantly affected by glucose or cellulose, indicating nitrogen rather than energy limitation. Since the stimulation of SOM decomposition in cryoturbated material was not connected to microbial growth or to a change in microbial community composition, the additional nitrogen was likely invested in the production of extracellular enzymes required for SOM decomposition. Our findings provide a first mechanistic understanding of priming in permafrost soils and suggest that an increase in the availability of organic carbon or nitrogen, e.g., by increased plant productivity, can change the decomposition of SOM stored in deeper layers of permafrost soils, with possible repercussions on the global climate.
authors.affiliation: University of Vienna, Department of Microbiology and Ecosystem Science, Division of Terrestrial Ecosystem Research, Vienna, Austria ; Austrian Polar Research Institute, Vienna, Austria.
authors.forename: Birgit
authors.initials: B
authors.lastname: Wild
authors.affiliation: University of Vienna, Department of Microbiology and Ecosystem Science, Division of Terrestrial Ecosystem Research, Vienna, Austria ; Austrian Polar Research Institute, Vienna, Austria.
authors.forename: Jörg
authors.initials: J
authors.lastname: Schnecker
authors.affiliation: Austrian Polar Research Institute, Vienna, Austria ; University of Vienna, Department of Ecogenomics and Systems Biology, Division of Archaea Biology and Ecogenomics, Vienna, Austria.
authors.forename: Ricardo J Eloy
authors.initials: RJ
authors.lastname: Alves
authors.affiliation: Siberian Branch of the Russian Academy of Sciences, Institute of Soil Science and Agrochemistry, Novosibirsk, Russia.
authors.forename: Pavel
authors.initials: P
authors.lastname: Barsukov
authors.affiliation: University of South Bohemia, Department of Ecosystems Biology, České Budějovice, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Bárta
authors.affiliation: University of South Bohemia, Department of Ecosystems Biology, České Budějovice, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Capek
authors.affiliation: Leibniz University Hannover, Institute of Soil Science, Hannover, Germany.
authors.forename: Norman
authors.initials: N
authors.lastname: Gentsch
authors.affiliation: Austrian Polar Research Institute, Vienna, Austria ; University of Bergen, Centre for Geobiology, Department of Biology, Bergen, Norway.
authors.forename: Antje
authors.initials: A
authors.lastname: Gittel
authors.affiliation: Leibniz University Hannover, Institute of Soil Science, Hannover, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Guggenberger
authors.affiliation: Siberian Branch of Russian Academy of Sciences, Central Siberian Botanical Garden, Novosibirsk, Russia.
authors.forename: Nikolay
authors.initials: N
authors.lastname: Lashchinskiy
authors.affiliation: Leibniz University Hannover, Institute of Soil Science, Hannover, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Mikutta
authors.affiliation: Siberian Branch of the Russian Academy of Sciences, Institute of Soil Science and Agrochemistry, Novosibirsk, Russia.
authors.forename: Olga
authors.initials: O
authors.lastname: Rusalimova
authors.affiliation: University of South Bohemia, Department of Ecosystems Biology, České Budějovice, Czech Republic.
authors.forename: Hana
authors.initials: H
authors.lastname: Santrůčková
authors.affiliation: Leibniz University Hannover, Institute of Soil Science, Hannover, Germany ; Siberian Branch of Russian Academy of Sciences, VN Sukachev Institute of Forest, Krasnoyarsk, Russia.
authors.forename: Olga
authors.initials: O
authors.lastname: Shibistova
authors.affiliation: Austrian Polar Research Institute, Vienna, Austria ; University of Vienna, Department of Ecogenomics and Systems Biology, Division of Archaea Biology and Ecogenomics, Vienna, Austria.
authors.forename: Tim
authors.initials: T
authors.lastname: Urich
authors.affiliation: University of Vienna, Department of Microbiology and Ecosystem Science, Division of Terrestrial Ecosystem Research, Vienna, Austria.
authors.forename: Margarete
authors.initials: M
authors.lastname: Watzka
authors.affiliation: Siberian Branch of Russian Academy of Sciences, VN Sukachev Institute of Forest, Krasnoyarsk, Russia.
authors.forename: Galina
authors.initials: G
authors.lastname: Zrazhevskaya
authors.affiliation: University of Vienna, Department of Microbiology and Ecosystem Science, Division of Terrestrial Ecosystem Research, Vienna, Austria ; Austrian Polar Research Institute, Vienna, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Richter
keywords: Organic matter decomposition; Permafrost; Phospholipid fatty acid (PLFA); Priming; Tundra
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