Contrasted effects of simulated drought on the production and oxidation of methane in a mid-Wales wetland

Freeman, Chris; Nevison, G. B.; Kang, Hojeong; Hughes, S.; Reynolds, B.; Hudson, J.A.

doi:10.1016/s0038-0717(01)00154-7

Cited by 69 publications

(35 citation statements)

References 28 publications

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“…Also, CH 4 release did not reappear during the third phase. This confirms findings by Freeman et al (2002) who reports a suppression of CH 4 for >1 month following a drought and Segers (1998) stated that, due slow growth rates, methanogens require a long regeneration period following exposition to oxygen. So we are not able to report a hysteresis in CH 4 release for the falling and rising limb as detected by Moore and Dalva (1993).…”

Section: Methanesupporting

confidence: 89%

Small scale controls of greenhouse gas release under elevated N deposition rates in a restoring peat bog in NW Germany

Glatzel

Forbrich

Kruger³

et al. 2008

Biogeosciences

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Abstract. In Central Europe, most bogs have a history of drainage and many of them are currently being restored. Success of restoration as well as greenhouse gas exchange of these bogs is influenced by environmental stress factors as drought and atmospheric nitrogen deposition. We determined the methane and nitrous oxide exchange of sites in the strongly decomposed center and less decomposed edge of the Pietzmoor bog in NW Germany in 2004. Also, we examined the methane and nitrous oxide exchange of mesocosms from the center and edge before, during, and following a drainage experiment as well as carbon dioxide release from disturbed unfertilized and nitrogen fertilized surface peat. In the field, methane fluxes ranged from 0 to 3.8 mg m −2 h −1 and were highest from hollows. Field nitrous oxide fluxes ranged from 0 to 574 µg m −2 h −1 and were elevated at the edge. A large Eriophorum vaginatum tussock showed decreasing nitrous oxide release as the season progressed. Drainage of mesocosms decreased methane release to 0, even during rewetting. There was a tendency for a decrease of nitrous oxide release during drainage and for an increase in nitrous oxide release during rewetting. Nitrogen fertilization did not increase decomposition of surface peat. Our examinations suggest a competition between vascular vegetation and denitrifiers for excess nitrogen. We also provide evidence that the von Post humification index can be used to explain nitrous oxide release from bogs, if the role of vascular vegetation is also considered. An assessment of the greenhouse gas release from nitrogen saturated restoring bogs needs to take into account elevated release from fresh Sphagnum peat as well as from sedges growing on decomposed peat. Given the high atmospheric nitrogen deposition, restoration will not be able to achieve an oligotrophic ecosystem in the short term.

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Section: Methanesupporting

confidence: 89%

Small scale controls of greenhouse gas release under elevated N deposition rates in a restoring peat bog in NW Germany

Glatzel

Forbrich

Kruger³

et al. 2008

Biogeosciences

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“…In fact, data from permanently inundated sites shows a slow-down of decomposition processes (Freeman et al, 2002) yielding to carbon accumulation in the soil, i.e. peat growth (Clymo et al, 1998).…”

Section: Discussionmentioning

confidence: 99%

Climate-CH<sub>4</sub> feedback from wetlands and its interaction with the climate-CO<sub>2</sub> feedback

et al. 2011

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Abstract. The existence of a feedback between climate and methane (CH 4 ) emissions from wetlands has previously been hypothesized, but both its sign and amplitude remain unknown. Moreover, this feedback could interact with the climate-CO 2 cycle feedback, which has not yet been accounted for at the global scale. These interactions relate to (i) the effect of atmospheric CO 2 on methanogenic substrates by virtue of its fertilizing effect on plant productivity and (ii) the fact that a climate perturbation due to CO 2 (respectively CH 4 ) radiative forcing has an effect on wetland CH 4 emissions (respectively CO 2 fluxes at the surface/atmosphere interface).We present a theoretical analysis of these interactions, which makes it possible to express the magnitude of the feedback for CO 2 and CH 4 alone, the additional gain due to interactions between these two feedbacks and the effects of these feedbacks on the difference in atmospheric CH 4 and CO 2 between 2100 and pre-industrial time (respectively CH 4 and CO 2 ). These gains are expressed as functions of different sensitivity terms, which we estimate based on prior studies and from experiments performed with the global terrestrial vegetation model ORCHIDEE.Despite high uncertainties on the sensitivity of wetland CH 4 emissions to climate, we found that the absolute value of the gain of the climate-CH 4 feedback from wetlands is relatively low (<30 % of climate-CO 2 feedback gain), with either negative or positive sign within the range of estimates.Correspondence to: B. Ringeval (bruno.ringeval@lsce.ipsl.fr) Whereas the interactions between the two feedbacks have low influence on CO 2 , the CH 4 could increase by 475 to 1400 ppb based on the sign of the C-CH 4 feedback gain.Our study suggests that it is necessary to better constrain the evolution of wetland area under future climate change as well as the local coupling through methanogenesis substrate of the carbon and CH 4 cycles -in particular the magnitude of the CO 2 fertilization effect on the wetland CH 4 emissions -as these are the dominant sources of uncertainty in our model.

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“…Freshwater wetlands may account for 20-39% of the total global methane emissions and as much as 90% of natural emissions (Denman et al 2007). Previous studies have measured highly variable rates of methane production in wetland sediments (Schimel 1995, Whalen and Reeburgh 2000, Krü ger et al 2001, Freeman et al 2002, Megonigal and Schlesinger 2002, Keller et al 2005, Welsch and Yavitt 2007, Sutton-Grier and Megonigal 2011 but the controlling factors contributing to this variability are still not well understood. Despite the significance of freshwater wetlands as a source of methane, this continued uncertainty about controls on sediment methane cycling stresses the need for further research of belowground processes.…”

Section: Introductionmentioning

confidence: 99%

Plant community structure mediates potential methane production and potential iron reduction in wetland mesocosms

et al. 2013

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Abstract. Wetlands are the largest natural source of methane to the atmosphere, but factors controlling methane emissions from wetlands are a major source of uncertainty in greenhouse gas budgets and projections of future climate change. We conducted a controlled outdoor mesocosm experiment to assess the effects of plant community structure (functional group richness and composition) on potential methane production and potential iron reduction in freshwater emergent marshes. Four plant functional groups (facultative annuals, obligate annuals, reeds, and tussocks) were arranged in a full-factorial design and additional mesocosms were assigned as no-plant controls. Soil samples from the top 10 cm were collected three times during the growing season to determine potential methane production and potential iron reduction (in unamended soils and in soils amended with 200 mM formate). These data were compared to soil organic matter, soil pH, and previously published data on above and belowground plant biomass. We found that functional group richness was less important than the presence of specific functional groups (reeds or tussocks) in mediating potential iron reduction. In our mesocosms, where oxidized iron was abundant and electron donors were limiting, iron reducing bacteria outcompeted methanogens, keeping methane production barely detectable in unamended lab incubations. When the possibility of re-oxidizing iron was eliminated via anaerobic incubations and the electron donor limitation was removed by adding formate, potential methane production increased and followed the same patterns as potential iron reduction. Our findings suggest that in the absence of abundant oxidized iron and/or the presence of abundant electron donors, wetlands dominated by either reeds or tussocks may have increased methane production compared to wetlands dominated by annuals. Depending on functional traits such as plant transport and rhizospheric oxygenation capacities, this could potentially lead to increased methane emissions in some wetlands. Additional research examining the role these plant functional groups play in other aspects of methane dynamics will be useful given the importance of methane as a greenhouse gas.

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Contrasted effects of simulated drought on the production and oxidation of methane in a mid-Wales wetland

Cited by 69 publications

References 28 publications

Small scale controls of greenhouse gas release under elevated N deposition rates in a restoring peat bog in NW Germany

Small scale controls of greenhouse gas release under elevated N deposition rates in a restoring peat bog in NW Germany

Climate-CH<sub>4</sub> feedback from wetlands and its interaction with the climate-CO<sub>2</sub> feedback

Plant community structure mediates potential methane production and potential iron reduction in wetland mesocosms

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Contrasted effects of simulated drought on the production and oxidation of methane in a mid-Wales wetland

Cited by 69 publications

References 28 publications

Small scale controls of greenhouse gas release under elevated N deposition rates in a restoring peat bog in NW Germany

Small scale controls of greenhouse gas release under elevated N deposition rates in a restoring peat bog in NW Germany

Climate-CH&lt;sub&gt;4&lt;/sub&gt; feedback from wetlands and its interaction with the climate-CO&lt;sub&gt;2&lt;/sub&gt; feedback

Plant community structure mediates potential methane production and potential iron reduction in wetland mesocosms

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Climate-CH<sub>4</sub> feedback from wetlands and its interaction with the climate-CO<sub>2</sub> feedback