Shifting environmental controls on CH&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt; fluxes in a sub-boreal peatland

Pypker, Thomas G.; Moore, Paul A.; Waddington, J. M.; Hribljan, John A.; Chimner, R. C.

doi:10.5194/bg-10-7971-2013

Cited by 25 publications

(12 citation statements)

References 71 publications

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“…The magnitude of daily methane fluxes at Kopuatai during November to January (i.e., summer; Figure 2) was 100-200 mg CH 4 m À2 d À1 , within the range of peak ecosystem-scale values reported for Northern Hemisphere fens [Olson et al, 2013;Pypker et al, 2013] but generally higher than Northern Hemisphere bogs [Brown et al, 2014;Nadeau et al, 2013]. At Kopuatai, litter decomposition rates are comparable to Northern Hemisphere bogs [Clarkson et al, 2014], and the peat is also acidic (pH~4) [Agnew et al, 1993;Clarkson et al, 2004], suggesting that these factors do not contribute to the observed differences between fluxes at Kopuatai and those of Northern Hemisphere bogs.…”

Section: Annual and Daily Methane Flux Magnitudessupporting

confidence: 65%

Overriding control of methane flux temporal variability by water table dynamics in a Southern Hemisphere, raised bog

Goodrich

Campbell

Roulet

et al. 2015

J. Geophys. Res. Biogeosci.

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There are still large uncertainties in peatland methane flux dynamics and insufficient understanding of how biogeochemical processes scale to ecosystems. New Zealand bogs differ from Northern Hemisphere ombrotrophic systems in climatic setting, hydrology, and dominant vegetation, offering an opportunity to evaluate our knowledge of peatland methane biogeochemistry gained primarily from northern bogs and fens. We report eddy covariance methane fluxes from a raised bog in New Zealand over 2.5 years. Annual total methane flux in 2012 was 29.1 g CH 4 m À2 yr À1 , whereas during a year with a severe drought (2013) A correlation between daytime CO 2 uptake and methane fluxes emerged during times with shallow water tables, suggesting that controls on methane production were critical in determining fluxes, more so than oxidation. Water table recession through this shallow zone led to increasing methane fluxes, whereas changes in temperature during these periods were not correlated. Models of methane fluxes should consider drought-induced lags in seasonal flux recovery that depend on drought characteristics and location of the critical zone for methane production.

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Section: Annual and Daily Methane Flux Magnitudessupporting

confidence: 65%

Overriding control of methane flux temporal variability by water table dynamics in a Southern Hemisphere, raised bog

Goodrich

Campbell

Roulet

et al. 2015

J. Geophys. Res. Biogeosci.

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“…The sedges also act as conduits for CH 4 , allowing the CH 4 produced below water level to rapidly escape to the atmosphere and bypass the oxic zone in which the CH 4 might have otherwise been oxidized (Waddington et al, 1996;Whiting and Chanton, 1992). Besides sedges, Spaghnum mosses are also important because methanotrophic bacteria that live in symbiosis with these mosses significantly decrease the CH 4 emissions to the atmosphere when they are present (Larmola et al, 2010;Liebner et al, 2011;Parmentier et al, 2011b;Raghoebarsing et al, 2005;Sundh et al, 1995). In a modelling study, Li et al (2016) showed that it was essential to consider the vegetation differences between sites when modelling CH 4 emissions from two northern peatlands.…”

Section: Missing Predictorsmentioning

confidence: 99%

Monthly gridded data product of northern wetland methane emissions based on upscaling eddy covariance observations

Peltola

Vesala

Gao

et al. 2019

Earth Syst. Sci. Data

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Abstract. Natural wetlands constitute the largest and most uncertain source of methane (CH4) to the atmosphere and a large fraction of them are found in the northern latitudes. These emissions are typically estimated using process (“bottom-up”) or inversion (“top-down”) models. However, estimates from these two types of models are not independent of each other since the top-down estimates usually rely on the a priori estimation of these emissions obtained with process models. Hence, independent spatially explicit validation data are needed. Here we utilize a random forest (RF) machine-learning technique to upscale CH4 eddy covariance flux measurements from 25 sites to estimate CH4 wetland emissions from the northern latitudes (north of 45∘ N). Eddy covariance data from 2005 to 2016 are used for model development. The model is then used to predict emissions during 2013 and 2014. The predictive performance of the RF model is evaluated using a leave-one-site-out cross-validation scheme. The performance (Nash–Sutcliffe model efficiency =0.47) is comparable to previous studies upscaling net ecosystem exchange of carbon dioxide and studies comparing process model output against site-level CH4 emission data. The global distribution of wetlands is one major source of uncertainty for upscaling CH4. Thus, three wetland distribution maps are utilized in the upscaling. Depending on the wetland distribution map, the annual emissions for the northern wetlands yield 32 (22.3–41.2, 95 % confidence interval calculated from a RF model ensemble), 31 (21.4–39.9) or 38 (25.9–49.5) Tg(CH4) yr−1. To further evaluate the uncertainties of the upscaled CH4 flux data products we also compared them against output from two process models (LPX-Bern and WetCHARTs), and methodological issues related to CH4 flux upscaling are discussed. The monthly upscaled CH4 flux data products are available at https://doi.org/10.5281/zenodo.2560163 (Peltola et al., 2019).

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“…Likewise, models of CH 4 emission consider soil temperature as a main driver (Bridgham, Cadillo-Quiroz, Keller, & Zhuang, 2013;Walter & Heimann, 2000). However, a combined chamber and eddy covariance study by Pypker, Moore, Waddington, Hribljan, and Chimner (2013) shows that daily mean soil temperature at 20 cm depth was poorly correlated with changes in CH 4 (17%) when the ecosystem represented a net CO 2 sink (negative net ecosystem exchange, NEE), but the correlation increased to 34% when it was a net CO 2 source (positive NEE). This indicates shifting temperature controls on the CH 4 flux throughout the growing season (Treat et al, 2007).…”

Section: Methane Emissions From Northern Natural Peatlandsmentioning

confidence: 99%

Emissions of methane from northern peatlands: a review of management impacts and implications for future management options

Abdalla

Hastings

Truu

et al. 2016

Ecology and Evolution

162

139

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Northern peatlands constitute a significant source of atmospheric methane (CH 4). However, management of undisturbed peatlands, as well as the restoration of disturbed peatlands, will alter the exchange of CH 4 with the atmosphere. The aim of this systematic review and meta‐analysis was to collate and analyze published studies to improve our understanding of the factors that control CH 4 emissions and the impacts of management on the gas flux from northern (latitude 40° to 70°N) peatlands. The analysis includes a total of 87 studies reporting measurements of CH 4 emissions taken at 186 sites covering different countries, peatland types, and management systems. Results show that CH 4 emissions from natural northern peatlands are highly variable with a 95% CI of 7.6–15.7 g C m−2 year−1 for the mean and 3.3–6.3 g C m−2 year−1 for the median. The overall annual average (mean ± SD) is 12 ± 21 g C m−2 year−1 with the highest emissions from fen ecosystems. Methane emissions from natural peatlands are mainly controlled by water table (WT) depth, plant community composition, and soil pH. Although mean annual air temperature is not a good predictor of CH 4 emissions by itself, the interaction between temperature, plant community cover, WT depth, and soil pH is important. According to short‐term forecasts of climate change, these complex interactions will be the main determinant of CH 4 emissions from northern peatlands. Drainage significantly (p < .05) reduces CH 4 emissions to the atmosphere, on average by 84%. Restoration of drained peatlands by rewetting or vegetation/rewetting increases CH 4 emissions on average by 46% compared to the original premanagement CH 4 fluxes. However, to fully evaluate the net effect of management practice on the greenhouse gas balance from high latitude peatlands, both net ecosystem exchange (NEE) and carbon exports need to be considered.

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Shifting environmental controls on CH<sub>4</sub> fluxes in a sub-boreal peatland

Cited by 25 publications

References 71 publications

Overriding control of methane flux temporal variability by water table dynamics in a Southern Hemisphere, raised bog

Overriding control of methane flux temporal variability by water table dynamics in a Southern Hemisphere, raised bog

Monthly gridded data product of northern wetland methane emissions based on upscaling eddy covariance observations

Emissions of methane from northern peatlands: a review of management impacts and implications for future management options

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