Title: Radiocarbon Analyses Quantify Peat Carbon Losses With Increasing Temperature in a Whole Ecosystem Warming Experiment

Abstract

Climate warming is expected to accelerate peatland degradation and release rates of carbon dioxide (CO₂) and methane (CH₄). Spruce and Peatlands Responses Under Changing Environments is an ecosystem-scale climate manipulation experiment, designed to examine peatland ecosystem response to climate forcings. We examined whether heating up to +9 °C to 3 m-deep in a peat bog over a 7-year period led to higher C turnover and CO₂ and CH₄ emissions, by measuring ¹⁴C of solid peat, dissolved organic carbon (DOC), CH₄, and dissolved CO₂ (DIC). DOC, a major substrate for heterotrophic respiration, increased significantly with warming. There was no 7-year trend in the DI¹⁴ C of the ambient plots which remained similar to their DO¹⁴ C. At +6.75 °C and +9 °C, the ¹⁴C of DIC, a product of microbial respiration, initially resembled ambient plots but became more depleted over 7 years of warming. We attributed the shifts in DI₁₄ C to the increasing importance of solid phase peat as a substrate for microbial respiration and quantified this shift via the radiocarbon mass balance. The mass-balance model revealed increases in peat-supported respiration of the catotelm depths in heated plots over time and relative to ambient enclosures, from a baseline of 20%–25%more » in ambient enclosures, to 35%–40% in the heated plots. We find that warming stimulates microorganisms to respire ancient peat C, deposited under prior climate (cooler) conditions. This apparent destabilization of the large peat C reservoir has implications for peatland-climate feedbacks especially if the balance of the peatland is tipped from net C sink to C source.« less

Authors:

Wilson, Rachel M.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-5770-9614"

Griffiths, Natalie A.  ^[2];

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Visser, Ate  ^[3];

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McFarlane, Karis J.  ^[3];

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Sebestyen, Stephen D. ^[4]; Oleheiser, Keith C. ^[2]; Bosman, Samantha ^[1]; Hopple, Anya M. ^[5]; Tfaily, Malak M.  ^[6];

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Kolka, Randall K.  ^[4];

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Hanson, Paul J.  ^[2];

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Kostka, Joel E. ^[7]; Bridgham, Scott D. ^[8]; Keller, Jason K. ^[9]; Chanton, Jeffrey P.  ^[1]

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• Search DOE PAGES for ORCID "0000-0002-3303-9708"

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+ Show Author Affiliations

1. Department of Earth Ocean and Atmospheric Science Florida State University Tallahassee FL USA
2. Oak Ridge National Laboratory Environmental Sciences Division Oak Ridge TN USA
3. Lawrence Livermore National Laboratory Livermore CA USA
4. US Department of Agriculture Forest Service Northern Research Station Grand Rapids MN USA
5. Institute of Ecology and Evolution University of Oregon Eugene OR USA, Pacific Northwest National Laboratory Smithsonian Environmental Research Center Edgewater MD USA
6. Department of Environmental Science University of Arizona Tucson AZ USA
7. School of Biological Sciences Georgia Institute of Technology Atlanta GA USA
8. Institute of Ecology and Evolution University of Oregon Eugene OR USA
9. Schmid College of Science and Technology Biological Sciences Chapman University Orange CA USA

Publication Date:

Wed Nov 10 00:00:00 EST 2021

Research Org.:

Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER); USDOE Laboratory Directed Research and Development (LDRD) Program

OSTI Identifier:

1829752

Alternate Identifier(s):

OSTI ID: 1829978; OSTI ID: 1831651; OSTI ID: 1832256

Report Number(s):

LLNL-JRNL-824193
Journal ID: ISSN 2169-8953; e2021JG006511

Grant/Contract Number:  

DE‐SC0007144; DE‐SC0012088; DE‐AC05‐00OR22725; DE‐AC52‐07NA27344; AC52-07NA27344; AC05-00OR22725; SC0007144; SC0012088

Resource Type:

Published Article

Journal Name:

Journal of Geophysical Research. Biogeosciences

Additional Journal Information:

Journal Name: Journal of Geophysical Research. Biogeosciences Journal Volume: 126 Journal Issue: 11; Journal ID: ISSN 2169-8953

Publisher:

American Geophysical Union (AGU)

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; 54 ENVIRONMENTAL SCIENCES; climate change; peatlands; carbon loss; radiocarbon; dissolved organic carbon; mass balance