title: Winter ecology of a subalpine grassland: Effects of snow removal on soil respiration, microbial structure and function.
abstract: Seasonal snow cover provides essential insulation for mountain ecosystems, but expected changes in precipitation patterns and snow cover duration due to global warming can influence the activity of soil microbial communities. In turn, these changes have the potential to create new dynamics of soil organic matter cycling. To assess the effects of experimental snow removal and advanced spring conditions on soil carbon (C) and nitrogen (N) dynamics, and on the biomass and structure of soil microbial communities, we performed an in situ study in a subalpine grassland in the Austrian Alps, in conjunction with soil incubations under controlled conditions. We found substantial winter C-mineralisation and high accumulation of inorganic and organic N in the topsoil, peaking at snowmelt. Soil microbial biomass doubled under the snow, paralleled by a fivefold increase in its C:N ratio, but no apparent change in its bacteria-dominated community structure. Snow removal led to a series of mild freeze-thaw cycles, which had minor effects on in situ soil CO2production and N mineralisation. Incubated soil under advanced spring conditions, however, revealed an impaired microbial metabolism shortly after snow removal, characterised by a limited capacity for C-mineralisation of both fresh plant-derived substrates and existing soil organic matter (SOM), leading to reduced priming effects. This effect was transient and the observed recovery in microbial respiration and SOM priming towards the end of the winter season indicated microbial resilience to short-lived freeze-thaw disturbance under field conditions. Bacteria showed a higher potential for uptake of plant-derived C substrates during this recovery phase. The observed temporary loss in microbial C-mineralisation capacity and the promotion of bacteria over fungi can likely impede winter SOM cycling in mountain grasslands under recurrent winter climate change events, with plausible implications for soil nutrient availability and plant-soil interactions.
authors.affiliation: Climate Impacts Research Centre, Department of Ecology and Environmental Science, Umeå University, 98107 Abisko, Sweden. Electronic address: konstantin.gavazov@umu.se.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Gavazov
authors.affiliation: Institute of Ecology, University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria.
authors.forename: Johannes
authors.initials: J
authors.lastname: Ingrisch
authors.affiliation: Institute of Ecology, University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria.
authors.forename: Roland
authors.initials: R
authors.lastname: Hasibeder
authors.affiliation: Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, United Kingdom.
authors.forename: Robert T E
authors.initials: RTE
authors.lastname: Mills
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne EPFL, School of Architecture, Civil and Environmental Engineering ENAC, Laboratory of Ecological Systems ECOS, Station 2, 1015 Lausanne, Switzerland; Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Site Lausanne, Station 2, 1015 Lausanne, Switzerland; Laboratoire de Chrono-Environnement, UMR CNRS 6249, UFR des Sciences et Techniques, 16 route de Gray, Université de Franche-Comté, 25030 Besançon, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Buttler
authors.affiliation: Max Planck Institute for Biogeochemistry, P.O. Box 100164, 07701 Jena, Germany.
authors.forename: Gerd
authors.initials: G
authors.lastname: Gleixner
authors.affiliation: Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland.
authors.forename: Jukka
authors.initials: J
authors.lastname: Pumpanen
authors.affiliation: Institute of Ecology, University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Bahn
mesh_terms: D001317:Austria; D002244:Carbon / Q000032:analysis; D057231:Climate Change; D065948:Grassland; D009584:Nitrogen / Q000032:analysis; D012621:Seasons; D012914:Snow; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology
chemical_list: D012987:Soil; D002244:Carbon; D009584:Nitrogen
keywords: Climate change; Fungal:Bacterial ratio; Microbial C:N; PLFA; Priming effect; Substrate induced respiration