A pulse-labeling experiment to determine the contribution of recent plant photosynthates to net methane emission in arctic wet sedge tundra

King, Jennifer Y.; Reeburgh, William S.

doi:10.1016/s0038-0717(01)00164-x

Cited by 119 publications

(72 citation statements)

References 41 publications

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“…Although less than one percent of the tracer amount had been taken up, calculated rates of CO 2 incorporation were 0.7-1.8 mmol C m −2 d −1 under vegetation, and thus in the same range as reported for arctic wet sedge tundra (King and Reeburgh, 2002). The labelling experiment demonstrated that in our peat, the rhizosphere associated respiration was mainly limited to the upper 10-20 cm.…”

Section: Respiration and Methanogenesissupporting

confidence: 82%

Fluxes and 13C isotopic composition of dissolved carbon and pathways of methanogenesis in a fen soil exposed to experimental drought

2008

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Abstract. Peatlands contain a carbon stock of global concern and significantly contribute to the global methane burden. The impact of drought and rewetting on carbon cycling in peatland ecosystems is thus currently debated. We studied the impact of experimental drought and rewetting on intact monoliths from a temperate fen over a period of ~300 days, using a permanently wet treatment and two treatments undergoing drought for 50 days. In one of the mesocosms, vegetation had been removed. Net production of CH4 was calculated from mass balances in the peat and emission using static chamber measurements. Results were compared to 13C isotope budgets of CO2 and CH4 and energy yields of acetoclastic and hydrogenotrophic methanogenesis. Drought retarded methane production after rewetting for days to weeks and promoted methanotrophic activity. Based on isotope and flux budgets, aerobic soil respiration contributed 32–96% in the wet treatment and 86–99% in the other treatments. Drying and rewetting did not shift methanogenic pathways according to δ13C ratios of CH4 and CO2. Although δ13C ratios indicated a prevalence of hydrogenotrophic methanogenesis, free energies of this process were small and often positive on the horizon scale. This suggests that methane was produced very locally. Fresh plant-derived carbon input apparently supported respiration in the rhizosphere and sustained methanogenesis in the unsaturated zone, according to a 13C-CO2 labelling experiment. The study documents that drying and rewetting in a rich fen soil may have little effect on methanogenic pathways, but result in rapid shifts between methanogenesis and methanotrophy. Such shifts may be promoted by roots and soil heterogeneity, as hydrogenotrophic methanogenesis occurred locally even when conditions were not conducive for this process in the bulk peat.

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Section: Respiration and Methanogenesissupporting

confidence: 82%

Fluxes and 13C isotopic composition of dissolved carbon and pathways of methanogenesis in a fen soil exposed to experimental drought

2008

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“…CH 4 flux depends on the balance between CH 4 production, oxidation and transport. Above-ground shoot clippings not only reduced the labile C into the soil (King and Reeburgh 2002;Ström et al 2012), but also simultaneously influenced plant mediated CH 4 transport and oxidation. For instance, increased CH 4 flux due to clipping of Carex aquatilis was attributed to the removal of the resistance to CH 4 flow within plant tissues (Schimel 1995).…”

Section: Impact Of Shoot Clipping and Root Exclusion On Ch 4 Fluxesmentioning

confidence: 99%

“…Plant presence can increase soil CH 4 flux by enhancing substrate availability. There is strong evidence showing that CH 4 emission is favored by photosynthates in the form of root exudates (King and Reeburgh 2002;Dorodnikov et al 2011;Ström et al 2012). The transport of oxygen from shoots to the rhizosphere via aerenchyma can lead to the suppression of methanogenesis and oxidation of CH 4 to CO 2 .…”

Section: Introductionmentioning

confidence: 99%

Plant-mediated methane and nitrous oxide fluxes from a carex meadow in Poyang Lake during drawdown periods

Cai

Yao

et al. 2015

Plant Soil

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Aims Plants have been suggested to have significant effects on methane (CH 4 ) and nitrous oxide (N 2 O) fluxes from littoral wetlands, but it remains unclear in subtropical lakes. Methods We conducted in situ measurement of CH 4 and N 2 O fluxes for two years. To distinguish between the effects of shoots and roots, three treatments (i.e., intact plants as control, shoot clipping, and root exclusion) were used. Effects of plant biomass, temperature, and soil moisture on CH 4 and N 2 O fluxes were analyzed. Results The mean ecosystem CH 4 emission rate was 36 μg CH 4 m −2 h −1 for drying periods, but 8219 μg CH 4 m −2 h −1 for drying-wetting transition periods. CH 4 fluxes were positively correlated with below-ground and total biomass, but not with above-ground biomass. Clipping did not significantly alter CH 4 flux rate, but root exclusion decreased the CH 4 flux by 116 % as compared to the control. N 2 O emissions were similar for both the drying and drying-wetting transition periods, with a mean rate of 20 μg N 2 O m −2 h −1 . Both clipping and root exclusion significantly increased N 2 O fluxes as compared to the control. Conclusions There was no significant correlation between CH 4 and N 2 O fluxes. Roots dominated plantmediated enhancement in CH 4 fluxes, but played almost an equal role as shoots in plant-regulated suppression on N 2 O fluxes in this Carex meadow during drawdown periods.

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“…A pulse-labeling experiment showed that recently-assimilated carbon was translocated to the roots and available to soil microbial community as root exudates and emitted as CH 4 quickly (King and Reeburgh, 2002). The low availability of appropriate organic substrate for methanogens caused the lack of CH 4 production from a Dutch cut-over bog remnant; peat with relatively low lignin and phenolic content, and with a low C:N, C:P and C:K ratio had a higher potential for CH 4 production (Smolders et al, 2002).…”

Section: Onset Of Methanogenesis and Magnitude Of Ch 4 Emissionsmentioning

confidence: 99%

Organic sediment formed during inundation of a degraded fen grassland emits large fluxes of CH4 and CO2

et al. 2011

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Abstract. Peatland restoration by inundation of drained areas can alter local greenhouse gas emissions as CO 2 and CH 4 . Factors that can influence these emissions include the quality and amount of substrates available for anaerobic degradation processes and the sources and availability of electron acceptors. In order to learn about possible sources of high CO 2 and CH 4 emissions from a rewetted degraded fen grassland, we performed incubation experiments that tested the effects of fresh plant litter in the flooded peats on pore water chemistry and CO 2 and CH 4 production and emission.The position in the soil profile of the pre-existing drained peat substrate affected initial rates of anaerobic CO 2 production subsequent to flooding, with the uppermost peat layer producing the greatest specific rates of CO 2 evolution. CH 4 production rates depended on the availability of electron acceptors and was significant only when sulfate concentrations were reduced in the pore waters. Very high specific rates of both CO 2 (maximum of 412 mg C d −1 kg −1 C) and CH 4 production (788 mg C d −1 kg −1 C) were observed in a new sediment layer that accumulated over the 2.5 years since the site was flooded. This new sediment layer was characterized by overall low C content, but represented a mixture of sand and relatively easily decomposable plant litter from reed canary grass killed by flooding. Samples that excluded this new sediment layer but included intact roots remaining from flooded grasses had specific rates of CO 2 (max. 28 mg C d −1 kg −1 C) and CH 4 (max. 34 mg C d −1 kg −1 C) production that were Correspondence to: M. Hahn-Schöfl (maria.hahn@yahoo.de) 10-20 times lower than for the new sediment layer and were comparable to those of a newly flooded upper peat layer. Lowest rates of anaerobic CO 2 and CH 4 production (range of 4-8 mg C d −1 kg −1 C and <1 mg C d −1 kg −1 C) were observed when all fresh organic matter sources (plant litter and roots) were excluded. In conclusion, the presence of fresh organic substrates such as plant and root litter originating from plants killed by inundation has a high potential for CH 4 production, whereas peat without any fresh plant-derived material is relatively inert. Significant anaerobic CO 2 and CH 4 production in peat only occurs when some labile organic matter is available, e.g. from remaining roots or root exudates.

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A pulse-labeling experiment to determine the contribution of recent plant photosynthates to net methane emission in arctic wet sedge tundra

Cited by 119 publications

References 41 publications

Fluxes and <sup>13</sup>C isotopic composition of dissolved carbon and pathways of methanogenesis in a fen soil exposed to experimental drought

Fluxes and <sup>13</sup>C isotopic composition of dissolved carbon and pathways of methanogenesis in a fen soil exposed to experimental drought

Plant-mediated methane and nitrous oxide fluxes from a carex meadow in Poyang Lake during drawdown periods

Organic sediment formed during inundation of a degraded fen grassland emits large fluxes of CH<sub>4</sub> and CO<sub>2</sub>

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A pulse-labeling experiment to determine the contribution of recent plant photosynthates to net methane emission in arctic wet sedge tundra

Cited by 119 publications

References 41 publications

Fluxes and &lt;sup&gt;13&lt;/sup&gt;C isotopic composition of dissolved carbon and pathways of methanogenesis in a fen soil exposed to experimental drought

Fluxes and &lt;sup&gt;13&lt;/sup&gt;C isotopic composition of dissolved carbon and pathways of methanogenesis in a fen soil exposed to experimental drought

Plant-mediated methane and nitrous oxide fluxes from a carex meadow in Poyang Lake during drawdown periods

Organic sediment formed during inundation of a degraded fen grassland emits large fluxes of CH&lt;sub&gt;4&lt;/sub&gt; and CO&lt;sub&gt;2&lt;/sub&gt;

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Fluxes and <sup>13</sup>C isotopic composition of dissolved carbon and pathways of methanogenesis in a fen soil exposed to experimental drought

Fluxes and <sup>13</sup>C isotopic composition of dissolved carbon and pathways of methanogenesis in a fen soil exposed to experimental drought

Organic sediment formed during inundation of a degraded fen grassland emits large fluxes of CH<sub>4</sub> and CO<sub>2</sub>