Upscaling methane emission hotspots in boreal peatlands

Aleina, Fabio Cresto; Runkle, Benjamin R. K.; Brücher, Tim; Kleinen, Thomas; Brovkin, Victor

doi:10.5194/gmd-9-915-2016

Cited by 12 publications

(11 citation statements)

References 44 publications

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“…However, there can also be a lag effect occurring during water-table fluctuations, with higher CH 4 emissions being recorded on water table drawdowns and drought periods and lower fluxes as the water table increases again (Brown et al, 2014). It is incredibly important that interannual variability is taken into account when measuring carbon fluxes, given the large range in annual flux that can occur (e.g., Roulet et al, 2007) in response to variable conditions arising from many sources including localised microtopography (Crestio Aleina, Runkle, Brücher, Kleinen, & Brovkin, 2016), temperature and hydrological regimes (Bubier, Moore, Savage, & Crill, 2005;Waddington et al, 2015), and vegetation cover (Strack et al, 2017;Ström, Mastenapov, & Christensen, 2005).…”

Section: Introductionmentioning

confidence: 99%

Controls on soil carbon dioxide and methane fluxes from a peat swamp vary by hydrogeomorphic setting

et al. 2019

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Carbon dynamics of temperate peat swamps are a largely understudied component of wetland carbon cycling. Under a changing climate, hydrometeorological conditions may change, and understanding how peat swamps may be impacted is important.We investigated the importance of hydrogeomorphic setting on controlling soil carbon dioxide (CO 2 ) and methane (CH 4 ) fluxes from a temperate peat swamp in southern Ontario, Canada over a 3-year period. We chose three different hydrogeomorphic settings: (a) a site with strong wetland-stream interactions (i.e., an unconfined stream channel; unconfined), (b) a site with limited wetland-stream interactions (confined), and (c) an interior site (no wetland-stream interaction). The differing hydrogeomorphic conditions between the sites resulted in differences in carbon fluxes. The unconfined site maintained a higher water table across all three study years, providing conditions that are not favourable to CO 2 production. The confined and interior sites sustained a much lower water table, with conditions more conducive to CO 2 efflux.The unconfined site also had the highest CH 4 emissions due to the increased anoxic conditions favourable for CH 4 production as a result of the higher water table position. Hydrogeomorphic setting was found to be important for understanding within site variation, suggesting the sites may respond differently to longer-term shifts in environmental conditions. This may change relationships between sites if the responses are strong enough to significantly alter carbon fluxes, decomposition, and potential peat accumulation rates. It is important to understand the locally specific responses to environmental conditions within peat swamp ecosystems, in order to make future predictions about whole ecosystem function under changing conditions.

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Section: Introductionmentioning

confidence: 99%

Controls on soil carbon dioxide and methane fluxes from a peat swamp vary by hydrogeomorphic setting

et al. 2019

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“…We then compared the extent of the wetlands to the inundated fractional area of the model grid cell considered as the corresponding model wet area. It has been recently shown in the literature that the type of vegetation in tundra landscapes is a good indicator of the spatial distribution and variation of CH 4 fluxes (Davidson et al, 2017), and it is also expected that the majority of the CH 4 fluxes are emitted from wetlands in tundra ecosystems (Helbig et al, 2017a). About 26 % of the fluxes measured by the EC tower were emitted from wetland areas within the footprint, i.e., from wet soils with cotton grasses.…”

Section: Eddy Covariance Measurementsmentioning

confidence: 99%

Year-round simulated methane emissions from a permafrost ecosystem in Northeast Siberia

Castro-Morales¹,

Kleinen²,

Kaiser³

et al. 2018

Biogeosciences

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Abstract. Wetlands of northern high latitudes are ecosystems highly vulnerable to climate change. Some degradation effects include soil hydrologic changes due to permafrost thaw, formation of deeper active layers, and rising topsoil temperatures that accelerate the degradation of permafrost carbon and increase in CO2 and CH4 emissions. In this work we present 2 years of modeled year-round CH4 emissions into the atmosphere from a Northeast Siberian region in the Russian Far East. We use a revisited version of the process-based JSBACH-methane model that includes four CH4 transport pathways: plant-mediated transport, ebullition and molecular diffusion in the presence or absence of snow. The gas is emitted through wetlands represented by grid cell inundated areas simulated with a TOPMODEL approach. The magnitude of the summertime modeled CH4 emissions is comparable to ground-based CH4 fluxes measured with the eddy covariance technique and flux chambers in the same area of study, whereas wintertime modeled values are underestimated by 1 order of magnitude. In an annual balance, the most important mechanism for transport of methane into the atmosphere is through plants (61 %). This is followed by ebullition ( ∼ 35 %), while summertime molecular diffusion is negligible (0.02 %) compared to the diffusion through the snow during winter ( ∼ 4 %). We investigate the relationship between temporal changes in the CH4 fluxes, soil temperature, and soil moisture content. Our results highlight the heterogeneity in CH4 emissions at landscape scale and suggest that further improvements to the representation of large-scale hydrological conditions in the model will facilitate a more process-oriented land surface scheme and better simulate CH4 emissions under climate change. This is especially necessary at regional scales in Arctic ecosystems influenced by permafrost thaw.

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“…CH 4 dynamics in peatlands results from a combination of various biogeochemical processes (Lai, 2009). Controls on CH 4 production, oxidation, and emissions include microtopography (Cresto Aleina et al, 2016), water table depth (Bubier et al, 1995;Granberg et al, 1997), soil temperature (Granberg et al, 1997;Saarnio et al, 1998), substrate quality and availability (Granberg et al, 1997;Segers, 1998;Joabsson et al, 1999), and vegetation cover (Ström et al, 2005;Strack et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

“…Despite the increasing pressures from wildfires across northern peatlands, a knowledge gap still persists on CH 4 emissions after wildfire, especially in boreal regions. In a study on the impact of wildfire on methanotrophic communities from an ombrotrophic peat bog, Danilova et al (2015) found a reduction in the activity of the methanotrophs in burned sites 7 years post-fire. This reduction following wildfire could therefore lead to a potential increase in CH 4 emissions from bog systems.…”

Section: Introductionmentioning

confidence: 99%

“…Conversely, studies at other bog sites in the UK report a decrease in emissions after fire (Ward et al, 2007;Davies et al, 2013). In non-peatland ecosystems across boreal regions, wildfire has been shown to cause an increase in CH 4 uptake (Burke et al, 1997;Song et al, 2017Song et al, , 2018. However, in permafrost zones, wildfires can often typically lead to substantial permafrost thaw and increasing moisture levels across the landscape (Gibson et al, 2018), potentially leading to an increase in CH 4 emissions (Kim and Tanaka, 2003;Turetsky et al, 2008;Olefeldt et al, 2013b;Helbig et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Wildfire overrides hydrological controls on boreal peatland methane emissions

et al. 2019

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Abstract. Boreal peatlands represent a globally important store of carbon, and disturbances such as wildfire can have a negative feedback to the climate. Understanding how carbon exchange and greenhouse gas (GHG) dynamics are impacted after a wildfire is important, especially as boreal peatlands may be vulnerable to changes in wildfire regime under a rapidly changing climate. However, given this vulnerability, there is very little in the literature on the impact such fires have on methane (CH4) emissions. This study investigated the effect of wildfire on CH4 emissions at a boreal fen near Fort McMurray, Alberta, Canada, that was partially burned by the Horse River Wildfire in 2016. We measured CH4 emissions and environmental variables (2017–2018) and CH4 production potential (2018) in two different microform types (hummocks and hollows) across a peat burn severity gradient (unburned (UB), moderately burned (MB), and severely burned (SB)). Results indicated a switch in the typical understanding of boreal peatland CH4 emissions. For example, emissions were significantly lower in the MB and SB hollows in both years compared to UB hollows. Interestingly, across the burned sites, hummocks had higher fluxes in 2017 than hollows at the MB and SB sites. We found typically higher emissions at the UB site where the water table was close to the surface. However, at the burned sites, no relationship was found between CH4 emissions and water table, even under similar hydrological conditions. There was also significantly higher CH4 production potential from the UB site than the burned sites. The reduction in CH4 emissions and production in the hollows at burned sites highlights the sensitivity of hollows to fire, removing labile organic material for potential methanogenesis. The previously demonstrated resistance of hummocks to fire also results in limited impact on CH4 emissions and likely faster recovery to pre-fire rates. Given the potential initial net cooling effect resulting from a reduction in CH4 emissions, it is important that the radiative effect of all GHGs following wildfire across peatlands is taken into account.

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Upscaling methane emission hotspots in boreal peatlands

Cited by 12 publications

References 44 publications

Controls on soil carbon dioxide and methane fluxes from a peat swamp vary by hydrogeomorphic setting

Controls on soil carbon dioxide and methane fluxes from a peat swamp vary by hydrogeomorphic setting

Year-round simulated methane emissions from a permafrost ecosystem in Northeast Siberia

Wildfire overrides hydrological controls on boreal peatland methane emissions

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