title: Loss of testate amoeba functional diversity with increasing frost intensity across a continental gradient reduces microbial activity in peatlands.
abstract: Soil microbial communities significantly contribute to global fluxes of nutrients and carbon. Their response to climate change, including winter warming, is expected to modify these processes through direct effects on microbial functions due to osmotic stress, and changing temperature regimes. Using four European peatlands reflecting different frequencies of frost events, we show that peatland testate amoeba communities diverge among sites with different winter climates, and that this is reflected through contrasting functions. We found that exposure to harder soil frost promoted species β-diversity (species turnover) thus shifting the community composition of testate amoebae. In particular, we found that harder soil frost, and lower water-soluble phenolic compounds, induced functional turnover through the decrease of large species (-68%, >80μm) and the increase of small-bodied mixotrophic species (i.e. Archerella flavum; +79%). These results suggest that increased exposure to soil frost could be highly limiting for large species while smaller species are more resistant. Furthermore, we found that β-glucosidase enzymatic activity, in addition to soil temperature, strongly depended of the functional diversity of testate amoebae (R2=0.95, ANOVA). Changing winter conditions can therefore strongly impact peatland decomposition process, though it remains unclear if these changes are carried-over to the growing season.
authors.affiliation: École Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory of Ecological Systems (ECOS), Bâtiment GR, Station 2, CH-1015 Lausanne, Switzerland; WSL - Swiss Federal Institute for Forest, Snow and Landscape Research, Site Lausanne, Station 2, Case postale 96, CH-1015 Lausanne, Switzerland. Electronic address: vincent.jassey@epfl.ch.
authors.forename: Vincent E J
authors.initials: VE
authors.lastname: Jassey
authors.affiliation: Laboratory of Wetland Ecology and Monitoring, Faculty of Geographical and Geological Sciences, Adam Mickiewicz University, Dzięgielowa 27, 61-680 Poznań, Poland.
authors.forename: Mariusz
authors.initials: M
authors.lastname: Lamentowicz
authors.affiliation: École Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory of Ecological Systems (ECOS), Bâtiment GR, Station 2, CH-1015 Lausanne, Switzerland; WSL - Swiss Federal Institute for Forest, Snow and Landscape Research, Site Lausanne, Station 2, Case postale 96, CH-1015 Lausanne, Switzerland; Department of Life Science and Biotechnologies, University of Ferrara, Corso Ercole I d'Este 32, I-44121 Ferrara, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Bragazza
authors.affiliation: École Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory of Ecological Systems (ECOS), Bâtiment GR, Station 2, CH-1015 Lausanne, Switzerland; WSL - Swiss Federal Institute for Forest, Snow and Landscape Research, Site Lausanne, Station 2, Case postale 96, CH-1015 Lausanne, Switzerland; Ecology and Biodiversity Group, Institute of Environmental Biology, Faculty of Science, Utrecht University, Padualaan 8, 3585 CH Utrecht, The Netherlands.
authors.forename: Maaike L
authors.initials: ML
authors.lastname: Hofsommer
authors.affiliation: École Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory of Ecological Systems (ECOS), Bâtiment GR, Station 2, CH-1015 Lausanne, Switzerland; WSL - Swiss Federal Institute for Forest, Snow and Landscape Research, Site Lausanne, Station 2, Case postale 96, CH-1015 Lausanne, Switzerland.
authors.forename: Robert T E
authors.initials: RT
authors.lastname: Mills
authors.affiliation: École Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory of Ecological Systems (ECOS), Bâtiment GR, Station 2, CH-1015 Lausanne, Switzerland; WSL - Swiss Federal Institute for Forest, Snow and Landscape Research, Site Lausanne, Station 2, Case postale 96, CH-1015 Lausanne, Switzerland; Université de Bourgogne Franche-Comté, UMR CNRS 6249 Chrono-Environnement, 16 route de Gray, F-25030 Besançon cedex, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Buttler
authors.affiliation: École Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory of Ecological Systems (ECOS), Bâtiment GR, Station 2, CH-1015 Lausanne, Switzerland; WSL - Swiss Federal Institute for Forest, Snow and Landscape Research, Site Lausanne, Station 2, Case postale 96, CH-1015 Lausanne, Switzerland.
authors.forename: Constant
authors.initials: C
authors.lastname: Signarbieux
authors.affiliation: École Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory of Ecological Systems (ECOS), Bâtiment GR, Station 2, CH-1015 Lausanne, Switzerland; WSL - Swiss Federal Institute for Forest, Snow and Landscape Research, Site Lausanne, Station 2, Case postale 96, CH-1015 Lausanne, Switzerland.
authors.forename: Bjorn J M
authors.initials: BJ
authors.lastname: Robroek
mesh_terms: D000656:Amoeba / Q000502:physiology*; D044822:Biodiversity; D005615:Freezing; D012987:Soil / Q000469:parasitology*; D053833:Wetlands
chemical_list: D012987:Soil
keywords: Beta-diversity; Enzymatic activity; Functional turnover; Mixotrophy; Phenolic compounds; Winter climate change