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Petro C, Carrell AA, Wilson RM, Duchesneau K, Noble-Kuchera S, Song T, Iversen CM, Childs J, Schwaner G, Chanton JP, Norby RJ, Hanson PJ, Glass JB, Weston DJ, Kostka JE. Climate drivers alter nitrogen availability in surface peat and decouple N 2 fixation from CH 4 oxidation in the Sphagnum moss microbiome. Glob Chang Biol 2023; 29:3159-3176. [PMID: 36999440 DOI: 10.1111/gcb.16651] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 12/20/2022] [Indexed: 05/03/2023]
Abstract
Peat mosses (Sphagnum spp.) are keystone species in boreal peatlands, where they dominate net primary productivity and facilitate the accumulation of carbon in thick peat deposits. Sphagnum mosses harbor a diverse assemblage of microbial partners, including N2 -fixing (diazotrophic) and CH4 -oxidizing (methanotrophic) taxa that support ecosystem function by regulating transformations of carbon and nitrogen. Here, we investigate the response of the Sphagnum phytobiome (plant + constituent microbiome + environment) to a gradient of experimental warming (+0°C to +9°C) and elevated CO2 (+500 ppm) in an ombrotrophic peatland in northern Minnesota (USA). By tracking changes in carbon (CH4 , CO2 ) and nitrogen (NH4 -N) cycling from the belowground environment up to Sphagnum and its associated microbiome, we identified a series of cascading impacts to the Sphagnum phytobiome triggered by warming and elevated CO2 . Under ambient CO2 , warming increased plant-available NH4 -N in surface peat, excess N accumulated in Sphagnum tissue, and N2 fixation activity decreased. Elevated CO2 offset the effects of warming, disrupting the accumulation of N in peat and Sphagnum tissue. Methane concentrations in porewater increased with warming irrespective of CO2 treatment, resulting in a ~10× rise in methanotrophic activity within Sphagnum from the +9°C enclosures. Warming's divergent impacts on diazotrophy and methanotrophy caused these processes to become decoupled at warmer temperatures, as evidenced by declining rates of methane-induced N2 fixation and significant losses of keystone microbial taxa. In addition to changes in the Sphagnum microbiome, we observed ~94% mortality of Sphagnum between the +0°C and +9°C treatments, possibly due to the interactive effects of warming on N-availability and competition from vascular plant species. Collectively, these results highlight the vulnerability of the Sphagnum phytobiome to rising temperatures and atmospheric CO2 concentrations, with significant implications for carbon and nitrogen cycling in boreal peatlands.
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Affiliation(s)
- Caitlin Petro
- Center for Microbial Dynamics and Infection, School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Alyssa A Carrell
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Rachel M Wilson
- Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, Florida, USA
| | - Katherine Duchesneau
- Center for Microbial Dynamics and Infection, School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Sekou Noble-Kuchera
- Center for Microbial Dynamics and Infection, School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Tianze Song
- Center for Microbial Dynamics and Infection, School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Colleen M Iversen
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
- Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Joanne Childs
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
- Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Geoff Schwaner
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
- Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Jeffrey P Chanton
- Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, Florida, USA
| | - Richard J Norby
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
- Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
- Department of Ecology & Evolutionary Biology, University of Tennessee, Knoxville, Tennessee, USA
| | - Paul J Hanson
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
- Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Jennifer B Glass
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - David J Weston
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
- Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Joel E Kostka
- Center for Microbial Dynamics and Infection, School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
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