Radiocarbon Analyses Quantify Peat Carbon Losses With Increasing Temperature in a Whole Ecosystem Warming Experiment
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- Department of Earth Ocean and Atmospheric Science Florida State University Tallahassee FL USA
- Oak Ridge National Laboratory Environmental Sciences Division Oak Ridge TN USA
- Lawrence Livermore National Laboratory Livermore CA USA
- US Department of Agriculture Forest Service Northern Research Station Grand Rapids MN USA
- Institute of Ecology and Evolution University of Oregon Eugene OR USA, Pacific Northwest National Laboratory Smithsonian Environmental Research Center Edgewater MD USA
- Department of Environmental Science University of Arizona Tucson AZ USA
- School of Biological Sciences Georgia Institute of Technology Atlanta GA USA
- Institute of Ecology and Evolution University of Oregon Eugene OR USA
- Schmid College of Science and Technology Biological Sciences Chapman University Orange CA USA
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% 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.
- Research Organization:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER); USDOE Laboratory Directed Research and Development (LDRD) Program
- Grant/Contract Number:
- DE‐SC0007144; DE‐SC0012088; DE‐AC05‐00OR22725; DE‐AC52‐07NA27344; AC52-07NA27344; AC05-00OR22725; SC0007144; SC0012088
- OSTI ID:
- 1829752
- Alternate ID(s):
- OSTI ID: 1829978; OSTI ID: 1831651; OSTI ID: 1832256
- Report Number(s):
- LLNL-JRNL-824193; e2021JG006511
- Journal Information:
- Journal of Geophysical Research. Biogeosciences, Journal Name: Journal of Geophysical Research. Biogeosciences Vol. 126 Journal Issue: 11; ISSN 2169-8953
- Publisher:
- American Geophysical Union (AGU)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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