Variations in snow depth modify N-related soil microbial abundances and functioning during winter in subalpine grassland

• Published in: Soil Biology and Biochemistry
• Main Authors: Jusselme, My-Dung, Saccone, Patrick, Zinger, Lucie, Faure, Mathieu, Le Roux, Xavier, Guillaumaud, Nadine, Bernard, Lionel, Clement, Jean-Christophe, Poly, Franck
• Other Authors: Laboratoire d'Ecologie Microbienne - UMR 5557 (LEM), Institut National de la Recherche Agronomique (INRA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-Ecole Nationale Vétérinaire de Lyon (ENVL), Institut d'écologie et des sciences de l'environnement de Paris (iEES), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Recherche Agronomique (INRA), Laboratoire d'Ecologie Alpine (LECA ), Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 ), University of Oulu, Evolution et Diversité Biologique (EDB), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Observatoire des Sciences de l'Univers de Grenoble (OSUG); CNRS-LECA; CNRS-"Zone-Atelier-Alpes"
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: Microbial abundance; Microbial functioning; Denitrification; Snowpack properties; Subalpine grassland; Nitrification; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; [SDV.EE]Life Sciences [q-bio]/Ecology; environment; [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology; Arctic; Climate change
• Online Access: https://hal.archives-ouvertes.fr/hal-01688390; https://doi.org/10.1016/j.soilbio.2015.09.013

International audience In alpine and arctic ecosystems, the snowpack has been shown to insulate soils from the winter climatic harshness. Ongoing climate change modifies snowpack quantity and quality, but the consequences of these changes on the soil functioning remain largely unknown. We benefited from a subalpine landscape of the French Alps where, 700 years ago, agricultural practices led to the formation of terraces. Subsequently , on each terrace, snow thickness patterns significantly differed between the bank and the front areas inducing strong divergence in their soil microclimatic conditions. Using this framework, we measured abundances and activities of nitrifiers and denitrifiers, together with a set of environmental variables, on three grassland terraces between December and May to test the following hypotheses: (i) soil N-related microbial abundances and activities are sensitive to soil microclimatic variations and differ along the terrace snow depth gradient during winter, (ii) a thicker snowpack favors higher abundances and activities, and (iii) the driving forces for nitrification and denitrification abundances and activities vary along the snow depth gradient. Our results showed significantly and changing N-related microbial activities and abundances during winter despite partly frozen soils, and suggested the selection and/or adaptation of psychrophilic microbial communities. Moreover, activities as well as abundances of ni-trifiers and denitrifiers were significantly higher under a weak or absent snowpack during winter, and mostly related to soil water content and soil surface temperature according to our models. We suggest that strongly variable soil abiotic conditions at the front stations enabled the release of nutrients from soil organic and inorganic compounds favoring psychrophilic bacterial abundances and activities. Contrastingly , a thicker and permanent snowpack maintained circum-zero soil temperatures during winter which limited the microbial community's turnover and release of ...