title: Predicting the Responses of Soil Nitrite-Oxidizers to Multi-Factorial Global Change: A Trait-Based Approach.
abstract: Soil microbial diversity is huge and a few grams of soil contain more bacterial taxa than there are bird species on Earth. This high diversity often makes predicting the responses of soil bacteria to environmental change intractable and restricts our capacity to predict the responses of soil functions to global change. Here, using a long-term field experiment in a California grassland, we studied the main and interactive effects of three global change factors (increased atmospheric CO2 concentration, precipitation and nitrogen addition, and all their factorial combinations, based on global change scenarios for central California) on the potential activity, abundance and dominant taxa of soil nitrite-oxidizing bacteria (NOB). Using a trait-based model, we then tested whether categorizing NOB into a few functional groups unified by physiological traits enables understanding and predicting how soil NOB respond to global environmental change. Contrasted responses to global change treatments were observed between three main NOB functional types. In particular, putatively mixotrophic Nitrobacter, rare under most treatments, became dominant under the 'High CO2+Nitrogen+Precipitation' treatment. The mechanistic trait-based model, which simulated ecological niches of NOB types consistent with previous ecophysiological reports, helped predicting the observed effects of global change on NOB and elucidating the underlying biotic and abiotic controls. Our results are a starting point for representing the overwhelming diversity of soil bacteria by a few functional types that can be incorporated into models of terrestrial ecosystems and biogeochemical processes.
authors.affiliation: UMR INRA 1418, UMR CNRS 5557, Microbial Ecology Centre, INRA, CNRS, Université Lyon 1, Université de Lyon Villeurbanne, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Le Roux
authors.affiliation: Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley CA, USA.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Bouskill
authors.affiliation: UMR 8079, AgroParisTech, Ecology Systematics and Evolution Laboratory, CNRS, Université Paris-Sud 11 Orsay, France.
authors.forename: Audrey
authors.initials: A
authors.lastname: Niboyet
authors.affiliation: UMR 8079, AgroParisTech, Ecology Systematics and Evolution Laboratory, CNRS, Université Paris-Sud 11 Orsay, France.
authors.forename: Laure
authors.initials: L
authors.lastname: Barthes
authors.affiliation: Ecosystem Science and Society Center, Department of Biological Sciences, Northern Arizona University, Flagstaff AZ, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Dijkstra
authors.affiliation: Department of Global Ecology, Carnegie Institution, Stanford University, Stanford CA, USA.
authors.forename: Chris B
authors.initials: CB
authors.lastname: Field
authors.affiliation: Ecosystem Science and Society Center, Department of Biological Sciences, Northern Arizona University, Flagstaff AZ, USA.
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Hungate
authors.affiliation: UMR INRA 1418, UMR CNRS 5557, Microbial Ecology Centre, INRA, CNRS, Université Lyon 1, Université de Lyon Villeurbanne, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Lerondelle
authors.affiliation: UMR INRA 1418, UMR CNRS 5557, Microbial Ecology Centre, INRA, CNRS, Université Lyon 1, Université de Lyon Villeurbanne, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Pommier
authors.affiliation: Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley CA, USA.
authors.forename: Jinyun
authors.initials: J
authors.lastname: Tang
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark Kongens Lyngby, Denmark.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Terada
authors.affiliation: UMR INRA 1418, UMR CNRS 5557, Microbial Ecology Centre, INRA, CNRS, Université Lyon 1, Université de Lyon Villeurbanne, France.
authors.forename: Maria
authors.initials: M
authors.lastname: Tourna
authors.affiliation: UMR INRA 1418, UMR CNRS 5557, Microbial Ecology Centre, INRA, CNRS, Université Lyon 1, Université de Lyon Villeurbanne, France.
authors.forename: Franck
authors.initials: F
authors.lastname: Poly
keywords: bacterial functional traits; elevated CO2; nitrifiers; nitrogen fertilisation; trait-based modeling