Near-zero methane emission from an abandoned boreal peatland pasture based on eddy covariance measurements

PLOS ONE, Nov 2019

Although estimates of the annual methane (CH4) flux from agriculturally managed peatlands exist, knowledge of controls over the variation of CH4 at different time-scales is limited due to the lack of high temporal-resolution data. Here we present CH4 fluxes measured from May 2014 to April 2016 using the eddy covariance technique at an abandoned peatland pasture in western Newfoundland, Canada. The goals of the study were to identify the controls on the seasonal variations in CH4 flux and to quantify the annual CH4 flux. The seasonal variation in daily CH4 flux was not strong in the two study years, however a few periods of pronounced emissions occurred in the late growing season. The daily average CH4 flux was small relative to other studies, ranging from -4.1 to 9.9 nmol m-2 s-1 in 2014–15 and from -7.1 to 12.1 nmol m-2 s-1 in 2015–16. Stepwise multiple regression was used to investigate controls on CH4 flux and this analysis found shifting controls on CH4 flux at different periods of the growing season. During the early growing season CH4 flux was closely related to carbon dioxide fixation rates, suggesting substrate availability was the main control. The peak growing season CH4 flux was principally controlled by the CH4 oxidation in 2014, where the CH4 flux decreased and increased with soil temperature at 50 cm and soil water content at 10 cm, but a contrasting temperature-CH4 relation was found in 2015. The late growing season CH4 flux was found to be regulated by the variation in water table level and air temperature in 2014. The annual CH4 emission was near zero in both study years (0.36 ± 0.30 g CH4 m-2 yr-1 in 2014–15 and 0.13 ± 0.38 g CH4 m-2 yr-1 in 2015–16), but fell within the range of CH4 emissions reported for agriculturally managed peatlands elsewhere.

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Near-zero methane emission from an abandoned boreal peatland pasture based on eddy covariance measurements

December Near-zero methane emission from an abandoned boreal peatland pasture based on eddy covariance measurements Mei Wang 0 1 2 3 Jianghua Wu 1 2 3 Junwei Luan 1 2 3 Peter Lafleur 1 3 Huai Chen 1 3 Xinbiao Zhu 1 3 0 School of Geographical Sciences, South China Normal University , Guangzhou , China , 3 International Center for Bamboo and Rattan , Beijing , China , 4 School of the Environment, Trent University , Peterborough, ON , Canada , 5 Key Laboratory of Mountain Ecological Restoration and Bio-resource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences , Chengdu , China , 6 Atlantic Forestry Centre, Canadian Forest Service, Natural Resources Canada , Corner Brook, NL , Canada 1 Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant (JW); Canada Foundation for Innovation-John R. Evans Leaders Fund (JW); Research & Development Corporation (RDC, NL)- Leverage R&D, RDC-Ignite R&D (JW); Agricultural Research Initiative (NL) (JW); Humber River Basin Research Initiative of NL (JW); Grenfell Campus' Start-up Research Fund (JW); Vice- 2 Sustainable Resource Management, Memorial University of Newfoundland , Corner Brook , Canada 3 Editor: Hojeong Kang, Yonsei University , REPUBLIC OF KOREA Although estimates of the annual methane (CH4) flux from agriculturally managed peatlands exist, knowledge of controls over the variation of CH4 at different time-scales is limited due to the lack of high temporal-resolution data. Here we present CH4 fluxes measured from May 2014 to April 2016 using the eddy covariance technique at an abandoned peatland pasture in western Newfoundland, Canada. The goals of the study were to identify the controls on the seasonal variations in CH4 flux and to quantify the annual CH4 flux. The seasonal variation in daily CH4 flux was not strong in the two study years, however a few periods of pronounced emissions occurred in the late growing season. The daily average CH4 flux was small relative to other studies, ranging from -4.1 to 9.9 nmol m-2 s-1 in 2014±15 and from -7.1 to 12.1 nmol m-2 s-1 in 2015±16. Stepwise multiple regression was used to investigate controls on CH4 flux and this analysis found shifting controls on CH4 flux at different periods of the growing season. During the early growing season CH4 flux was closely related to carbon dioxide fixation rates, suggesting substrate availability was the main control. The peak growing season CH4 flux was principally controlled by the CH4 oxidation in 2014, where the CH4 flux decreased and increased with soil temperature at 50 cm and soil water content at 10 cm, but a contrasting temperature-CH4 relation was found in 2015. The late growing season CH4 flux was found to be regulated by the variation in water table level and air temperature in 2014. The annual CH4 emission was near zero in both study years (0.36 ± 0.30 g CH4 m-2 yr-1 in 2014±15 and 0.13 ± 0.38 g CH4 m-2 yr-1 in 2015±16), but fell within the range of CH4 emissions reported for agriculturally managed peatlands elsewhere. - Data Availability Statement: The relevant data are all contained within the paper. Introduction Agricultural drainage is one of the most common management practices in northern peatlands. About 20% of pristine peatlands have been drained for agriculture, forestry, and peat President Research Fund (JW); the Graduate Student Stipend funding from the Institute for Biodiversity, Ecosystem Science, and Sustainability (IBES, NL) (JW); and Graduate Student Baseline Fellowship from School of Graduate Studies, Memorial University (MW). extraction, among which agriculture is now the most widespread human use for peatlands globally [1±5]. Although natural peatlands tend to be carbon dioxide (CO2) sinks and methane (CH4) sources, they have acted to cool global climate for the past several millennia, sequestrating ~20±30 g C m-2 yr-1 from the atmosphere, mainly due to slow decomposition rates of peat organic matter under waterlogged conditions [ 6,7 ]. Agricultural drainage leads to significant alterations of the hydrology and vegetation of peatlands [ 8 ], which can potentially affect their C cycle and their corresponding impact on climate [ 9 ]. However, the importance of managed peatlands for global CH4 cycling and climate regulation remains uncertain mainly due to the lack of knowledge of CH4 flux processes and the underlying mechanisms, which requires reliable high-frequency CH4 flux data to resolve [ 10 ]. CH4 has a significant climate warming potential, about 25 times that of CO2 on a 100-year time horizon, and variations in the CH4 flux can exert a significant impact on regional and global climate [ 11 ]. In peatlands, CH4 is produced by methanogenic archaea in the anaerobic layer and is emitted into the atmosphere through diffusion, ebullition and via plant aerenchyma [ 12 ]. Ebullition and plant transport are relatively (...truncated)


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Mei Wang, Jianghua Wu, Junwei Luan, Peter Lafleur, Huai Chen, Xinbiao Zhu. Near-zero methane emission from an abandoned boreal peatland pasture based on eddy covariance measurements, PLOS ONE, 2017, Volume 12, Issue 12, DOI: 10.1371/journal.pone.0189692