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

Author(s):

Rachel M. Wilson
Natalie A. Griffiths
Ate Visser
Karis J. McFarlane
Keith C. Oleheiser
Samantha Bosman
Anya M. Hopple
Malak M. Tfaily
Paul J. Hanson
Joel E. Kostka
Scott D. Bridgham
Jason K. Keller
Jeffrey P. Chanton

Year:

2021

Publication type:

Scientific Journal (JRNL)

Primary Station(s):

Northern Research Station

Source:

Journal of Geophysical Research: Biogeosciences

Description

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.

Citation

Wilson, Rachel M.; Griffiths, Natalie A.; Visser, Ate; McFarlane, Karis J.; Sebestyen, Stephen D.; Oleheiser, Keith C.; Bosman, Samantha; Hopple, Anya M.; Tfaily, Malak M.; Kolka, Randall K.; Hanson, Paul J.; Kostka, Joel E.; Bridgham, Scott D.; Keller, Jason K.; Chanton, Jeffrey P. 2021. Radiocarbon Analyses Quantify Peat Carbon Losses With Increasing Temperature in a Whole Ecosystem Warming Experiment. Journal of Geophysical Research: Biogeosciences. 126(11): e2021JG006511. 17 p. https://doi.org/10.1029/2021JG006511.

Cited

Publication Notes

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https://www.fs.usda.gov/treesearch/pubs/63544