Methane Efflux Measured by Eddy Covariance in Alaskan Upland Tundra Undergoing Permafrost Degradation

Taylor, M.; Celis, Gerardo; Ledman, Justin; Bracho, Rosvel; Schuur, Edward A. G.

doi:10.1029/2018jg004444

Cited by 34 publications

(59 citation statements)

References 75 publications

(117 reference statements)

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“…Taylor et al () represent an important point in an ongoing trend with the field. Only recently has the field begun to regularly publish full year data sets, and that is even rarer for high‐latitude systems.…”

Section: Main Textmentioning

confidence: 99%

“…While high‐latitude interannual flux measurements remain rare, in recent years towers have made considerable efforts to run continuously, bolstering our knowledge base on dormant season measurements (Figure c). It is increasingly clear that CH 4 fluxes in the dormant season comprise a large percentage of total ecosystem fluxes (Morin, Bohrer, Naor‐Azrieli, et al, ; Taylor et al, ; Zona et al, ) and that nongrowing season fluxes must be included when estimating regional CH 4 fluxes (Treat et al, ). One study in the arctic determined that dormant season fluxes were the dominant source to the annual budget (Zona et al, ).…”

Section: Temporal Distributionmentioning

confidence: 99%

“…Additionally, improvements in the power efficiency of instruments have made it possible to engineer solar and wind power solutions, untethering the towers from the power grid or from generators that are at least required to be near roads for frequent refueling. Taylor et al (2018) represent an important point in an ongoing trend with the field. Only recently has the field begun to regularly publish full year data sets, and that is even rarer for high-latitude systems.…”

Section: Main Textmentioning

confidence: 99%

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Advances in the Eddy Covariance Approach to CH₄ Monitoring Over Two and a Half Decades

Morin

2019

JGR Biogeosciences

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Receding permafrost may expose the largest store of sequestered carbon to microbes ready to convert it to greenhouse gases. The fluxes of biogenic gases associated with boreal wetlands have historically been difficult to measure, limiting our understanding of what may happen as permafrost thaws. The many difficulties in working in high‐latitude climates have dramatically limited our understanding on the spatial and temporal distribution of fluxes and what is likely to change with a warming climate. The use of the eddy covariance approach to measure methane emissions has been developing steadily over the past 26 years. Taylor et al. (2018, https://doi.org/10.1029/2018JG004444) is an excellent example of the advancements made in the field. Here I summarize the history of the eddy covariance methane literature, describe advancements in spatial and temporal coverage, and look at important drivers of methane emissions.

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Section: Main Textmentioning

confidence: 99%

Section: Temporal Distributionmentioning

confidence: 99%

Section: Main Textmentioning

confidence: 99%

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Advances in the Eddy Covariance Approach to CH₄ Monitoring Over Two and a Half Decades

Morin

2019

JGR Biogeosciences

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“…In the opposite process, methane consumption (methanotrophy) causes Recoδ 13 C to decline because the δ 13 CO 2 respired from CH 4 substrates is very negative (Whiticar, 1999). At CiPEHR, landscape-level CH 4 flux increases with seasonal thaw which indicates increasing methanotrophy throughout the season (Taylor et al, 2018) and net CH 4 flux from wetter areas accounts for less than 1% of annual Reco (CO 2 flux; Natali et al, 2015). Despite the small budget component of net CH 4 flux, dominant methanotrophy early in the season and progressively increasing methanogenesis could explain the Recoδ 13 C patterns in Deep-Wet areas.…”

Section: Moisture Effects On Recoδ 13 Cmentioning

confidence: 99%

Using Stable Carbon Isotopes of Seasonal Ecosystem Respiration to Determine Permafrost Carbon Loss

et al. 2019

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High latitude warming and permafrost thaw will expose vast stores of deep soil organic carbon (SOC) to decomposition. Thaw also changes water movement causing either wetter or drier soil. The fate of deep SOC under different thaw and moisture conditions is unclear. We measured weekly growing‐season δ13C of ecosystem respiration (Recoδ13C) across thaw and moisture conditions (Shallow‐Dry; Deep‐Dry; Deep‐Wet) in a soil warming manipulation. Deep SOC loss was inferred from known δ13C signatures of plant shoot, root, surface soil, and deep soil respiration. In addition, a 2‐year‐old vegetation removal treatment (No Veg) was used to isolate surface and deep SOC decomposition contributions to Reco. In No Veg, seasonal Recoδ13C indicated that deep SOC loss increased as the soil column thawed, while in vegetated areas, root contributions appeared to dominate Reco. The Recoδ13C differences between Shallow‐Dry and Deep‐Dry were significant but surprisingly small. This most likely suggests that, under dry conditions, soil warming stimulates root and surface SOC respiration with a negative 13C signature that opposes the more positive 13C signal from increased deep SOC respiration. In Deep‐Wet conditions, Recoδ13C suggests reduced deep SOC loss but could also reflect altered diffusion or methane (CH4) dynamics. Together, these results demonstrate that frequent Recoδ13C measurements can detect deep SOC loss and that plants confound the signal. In future studies, soil profile δ13C measurements, vegetation removal across thaw gradients, and isotopic effects of CH4 dynamics could further deconvolute deep SOC loss via surface Reco.

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“…Multidecadal observations of CH 4 fluxes from Arctic ecosystems would be ideal to identify the response of CH 4 fluxes to Arctic warming. However, studies of fall CH 4 emissions are sparse and inconsistent (Mastepanov et al, ; Mastepanov et al, ; Pirk et al, ; Sturtevant et al, ; Tagesson et al, ) or are of short duration (Taylor et al, ; Zona et al, ) limiting our understanding of the impact that ZC duration and dynamics have on CH 4 emissions from Arctic ecosystems.…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of Methane Emissions to Later Soil Freezing in Arctic Tundra Ecosystems

et al. 2019

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The atmospheric methane (CH 4 ) concentration, a potent greenhouse gas, is on the rise once again, making it critical to understand the controls on CH 4 emissions. In Arctic tundra ecosystems, a substantial part of the CH 4 budget originates from the cold season, particularly during the "zero curtain" (ZC), when soil remains unfrozen around 0°C. Due to the sparse data available at this time, the controls on cold season CH 4 emissions are poorly understood. This study investigates the relationship between the fall ZC and CH 4 emissions using long-term soil temperature measurements and CH 4 fluxes from four eddy covariance (EC) towers in northern Alaska. To identify the large-scale implication of the EC results, we investigated the temporal change of terrestrial CH 4 enhancements from the National Oceanic and Atmospheric Administration monitoring station in Utqiaġvik, AK, from 2001 to 2017 and their association with the ZC. We found that the ZC is extending later into winter (2.6 ± 0.5 days/year from 2001 to 2017) and that terrestrial fall CH 4 enhancements are correlated with later soil freezing (0.79 ± 0.18-ppb CH 4 day −1 unfrozen soil). ZC conditions were associated with consistently higher CH 4 fluxes than after soil freezing across all EC towers during the measuring period (2013)(2014)(2015)(2016)(2017). Unfrozen soil persisted after air temperature was well below 0°C suggesting that air temperature has poor predictive power on CH 4 fluxes relative to soil temperature. These results imply that later soil freezing can increase CH 4 loss and that soil temperature should be used to model CH 4 emissions during the fall.

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Methane Efflux Measured by Eddy Covariance in Alaskan Upland Tundra Undergoing Permafrost Degradation

Cited by 34 publications

References 75 publications

Advances in the Eddy Covariance Approach to CH₄ Monitoring Over Two and a Half Decades

Advances in the Eddy Covariance Approach to CH₄ Monitoring Over Two and a Half Decades

Using Stable Carbon Isotopes of Seasonal Ecosystem Respiration to Determine Permafrost Carbon Loss

Sensitivity of Methane Emissions to Later Soil Freezing in Arctic Tundra Ecosystems

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Methane Efflux Measured by Eddy Covariance in Alaskan Upland Tundra Undergoing Permafrost Degradation

Cited by 34 publications

References 75 publications

Advances in the Eddy Covariance Approach to CH4 Monitoring Over Two and a Half Decades

Advances in the Eddy Covariance Approach to CH4 Monitoring Over Two and a Half Decades

Using Stable Carbon Isotopes of Seasonal Ecosystem Respiration to Determine Permafrost Carbon Loss

Sensitivity of Methane Emissions to Later Soil Freezing in Arctic Tundra Ecosystems

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Advances in the Eddy Covariance Approach to CH₄ Monitoring Over Two and a Half Decades

Advances in the Eddy Covariance Approach to CH₄ Monitoring Over Two and a Half Decades