Mechanisms involved in the re-establishment of Sphagnum-dominated vegetation in rewetted bog remnants

Smolders, Alfons J. P.; Tomassen, H.B.M.; Mullekom, M. van; Lamers, Leon P. M.; Roelofs, J.G.M.

doi:10.1023/b:wetl.0000007195.25180.94

Cited by 50 publications

(79 citation statements)

References 38 publications

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“…This compound was previously shown to form after periodic acid treatment from the C 35 hopanetetrol derivatives, membrane rigidifiers produced by methanotrophic bacteria 10 . The natural 13 C contents of this compound (d 13 C ¼ 239.8‰) were substantially depleted relative to Sphagnum cell material and enriched compared to that of methane (Table 1), in accordance with its origin from serine-cycle (type II) methanotrophic bacteria 11 . Using this methanotrophic biological marker we were able to determine whether the methanotrophs associated with Sphagnum were actively growing.…”

mentioning

confidence: 76%

“…S. cuspidatum, collected from the Mariapeel nature reserve, was washed with demineralized water and incubated in 250-ml serum bottles in 5 g wet weight aliquots with 150 ml medium as described previously 8 . 13 C-or 12 C-CH 4 or CO 2 were added to final concentrations of 200 mM as specified in the text. The bottles were shaken at 150 r.p.m.…”

Section: Methodsmentioning

confidence: 99%

“…Molecular probes revealed the presence of the bacteria in the hyaline cells of the plant and on stem leaves. Incubation with 13 C-methane showed rapid in situ oxidation by these bacteria to carbon dioxide, which was subsequently fixed by Sphagnum, as shown by incorporation of 13 C-methane into plant sterols. In this way, methane acts as a significant (10-15%) carbon source for Sphagnum.…”

mentioning

confidence: 99%

“…The natural carbon isotope abundances of Sphagnum mosses in the field (d 13 C 226.5‰; Table 1) are consistent with our estimate that 15% of the carbon fixed by Sphagnum derives from isotopically depleted methane (that is, 256‰; Table 1). S. cuspidatum fixes carbon dioxide via the Calvin cycle, and is able to fractionate strongly against 13 C (up to 29‰) at high carbon dioxide concentrations (.2 mM) 12,13 . However, unlike vascular (semi-)aquatic plants such as rice, S. cuspidatum does not have aerenchyma 8 that facilitate the transport of atmospheric carbon dioxide.…”

mentioning

confidence: 99%

“…Therefore, at lower carbon dioxide concentrations, carbon assimilation by S. cuspidatum is limited by mass transfer, and carbon fractionation has been reported to decrease to at most 4‰ (refs 12, 13). Because the average carbon dioxide concentration in the field was approximately 0.16 mM, a range of 4-10‰ was used as a conservative estimate for carbon fractionation by S. cuspidatum in the field 12,13 . With this assumption, the data from Table 1 and a simple isotopic mass balance (see Methods), we calculated that methane contributed on average between 5% and 20% to the carbon fixed by S. cuspidatum in the field, in good agreement with the labelling results.…”

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confidence: 99%

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Methanotrophic symbionts provide carbon for photosynthesis in peat bogs

Raghoebarsing

Smolders²,

Schmid

et al. 2005

Nature

389

378

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Wetlands are the largest natural source of atmospheric methane 1 , the second most important greenhouse gas 2 . Methane flux to the atmosphere depends strongly on the climate 3 ; however, by far the largest part of the methane formed in wetland ecosystems is recycled and does not reach the atmosphere 4,5 . The biogeochemical controls on the efficient oxidation of methane are still poorly understood. Here we show that submerged Sphagnum mosses, the dominant plants in some of these habitats, consume methane through symbiosis with partly endophytic methanotrophic bacteria, leading to highly effective in situ methane recycling. Molecular probes revealed the presence of the bacteria in the hyaline cells of the plant and on stem leaves. Incubation with 13 C-methane showed rapid in situ oxidation by these bacteria to carbon dioxide, which was subsequently fixed by Sphagnum, as shown by incorporation of 13 C-methane into plant sterols. In this way, methane acts as a significant (10-15%) carbon source for Sphagnum. The symbiosis explains both the efficient recycling of methane and the high organic carbon burial in these wetland ecosystems.Peat bogs alternate between lawns and pools. Lawns are dominated by species that grow up to several decimetres above the water table. Pools are dominated by aquatic species, such as Sphagnum cuspidatum, that form layers of living plants below the water table. We investigated the methane-oxidizing activity of submerged S. cuspidatum from peat bog pools at different field locations in the Netherlands, and compared it to the activity of S. magellanicum and S. papillosum growing in lawns. The potential methane-oxidizing activity was substantially higher in the submerged mosses (Fig. 1). In control experiments with bog water, methane was not oxidized, indicating that the methanotrophic bacteria were mainly present on or in the living Sphagnum tissue.The identity and location of these methanotrophs was determined in a molecular approach. Total genomic DNA from washed Sphagnum plants was isolated and bacterial 16S ribosomal RNA genes were amplified, cloned into Escherichia coli, sequenced and analysed phylogenetically. One of the 16S rRNA gene sequences of the clone library was affiliated to a cluster of type II methanotrophs that contained acidophilic methanotrophs isolated from Sphagnum bogs, such as Methylocella palustris (identity 93%) 6 and Methylocapsa acidiphila (identity 93%) 7 .The full 16S rRNA gene sequence was used to design two specific oligonucleotide probes for fluorescence in situ hybridization (FISH). FISH was combined with serial sectioning of the stems and the stem leaves of multiple individuals of submerged S. cuspidatum. The methanotrophic bacterium targeted by the probes was the dominant methanotroph in S. cuspidatum sections, accounting for over 75% of

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mentioning

confidence: 76%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Methanotrophic symbionts provide carbon for photosynthesis in peat bogs

Raghoebarsing

Smolders²,

Schmid

et al. 2005

Nature

389

378

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References

2012

Restoration Ecology

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Overcoming establishment thresholds for peat mosses in human‐made bog pools

Temmink

Cruijsen

Smolders

et al. 2021

Ecological Applications

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Globally, peatlands have been affected by drainage and peat extraction, with adverse effects on their functioning and services. To restore peat-forming vegetation, drained bogs are being rewetted on a large scale. Although this practice results in higher groundwater levels, unfortunately it often creates deep lakes in parts where peat was extracted to greater depths than the surroundings. Revegetation of these deeper waters by peat mosses appears to be challenging due to strong abiotic feedbacks that keep these systems in an undesired bare state. In this study, we theoretically explore if a floating peat mat and an open human-made bog lake can be considered two alternative stable states using a simple model, and experimentally test in the field whether stable states are present, and whether a state shift can be accomplished using floating biodegradable structures that mimic buoyant peat. We transplanted two peat moss species into these structures (pioneer sp.Sphagnum cuspidatum and later-successional sp. S. palustre) with and without additional organic substrate. Our model suggests that these open human-made bog-lakes and floating peat mats can indeed be regarded as alternative stable states. Natural recovery by spontaneous peat moss growth, i.e. a state shift from open water to floating mats, is only possible when the water table is sufficiently shallow to avoid light limitation (<0.29 m at our site). Our experiment revealed that alternative stable states are present and that the floating structures facilitated the growth of pioneer S. cuspidatum and vascular plants. Organic substrate addition particularly facilitated vascular plant growth, which correlated to higher moss height. The structures remained too wet for the latesuccessional species S. palustre. We conclude that open water and floating peat mats in humanmade bog lakes can be considered two alternative stable states, and that temporary floating establishment structures can induce a state shift from the open water state to peat-forming vegetation state. These findings imply that for successful restoration, there is a clear water-depth threshold to enable peat moss growth and there is no need for addition of large amounts of donorpeat substrate. Correct species selection for restoration is crucial for success.

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Mechanisms involved in the re-establishment of Sphagnum-dominated vegetation in rewetted bog remnants

Cited by 50 publications

References 38 publications

Methanotrophic symbionts provide carbon for photosynthesis in peat bogs

Methanotrophic symbionts provide carbon for photosynthesis in peat bogs

References

Overcoming establishment thresholds for peat mosses in human‐made bog pools

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