Biodegradability of Vegetation-Derived Dissolved Organic Carbon in a Cool Temperate Ombrotrophic Bog

Pinsonneault, Andrew J.; Moore, Tim R.; Roulet, Nigel T.; Lapierre, Jean‐François

doi:10.1007/s10021-016-9984-z

Cited by 47 publications

(33 citation statements)

References 66 publications

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“…It is worth noting, however, that sampling took place during leaf-fall in the woodland and therefore these results are likely to be an annual maximum, whereas the peatland site has sources of year-round litter production so is likely to be less seasonal in litter quantity and thus DOC flux (Ritson et al, 2016). Our results on extractable DOC, C:N and BDOC of typical UK oak forest vegetation add to the findings of Pinsonneault et al, (2016) who published similar data for peatland vegetation. Our results suggest…”

Section: Accepted Manuscriptsupporting

confidence: 73%

Sources of dissolved organic carbon (DOC) in a mixed land use catchment (Exe, UK)

Ritson

Croft

Clark

et al. 2019

Science of The Total Environment

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Please cite this article as: J.P. Ritson, J.K. Croft, J.M. Clark, et al., Sources of dissolved organic carbon (DOC) in a mixed land use catchment (Exe, UK), Science of the Total Environment, https://doi. AbstractMany catchment management schemes in the UK have focussed on peatland restoration to improve ecosystem services such as carbon sequestration, water quality and biodiversity. The effect of these schemes on dissolved organic carbon (DOC) flux is critical in understanding peatland carbon budgets as well as the implications for drinking water treatment. In many catchments, however, peatland areas are not the only source of DOC, meaning that their significance at the full catchment scale is unclear. In this paper we have evaluated the importance of different land uses as sources of DOC by combining three datasets obtained from the Exe catchment, UK. The first dataset comprises a weekly monitoring record at three sites for six years, the second, a monthly monitoring record of 25 sites in the same catchment for one year, and the third, an assessment of DOC export from litter and soil carbon stocks. Our results suggest that DOC concentration significantly increased from the peaty headwaters to the mixed land-use areas (ANOVA F=12.52, p<0.001, df=2), leading to higher flux estimates at the downstream sites. We present evidence for three possible explanations: firstly, that poor sampling of high flows may lead to underestimation of DOC flux, second, that there are significant sources of DOC besides the peatland headwaters, and finally, that biological-and photodegradation decreases the influence of upstream DOC sources. Our results provide evidence both for the targeting of catchment management in peatland areas as well as the need to consider DOC from agricultural and forested areas of the catchment.

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Section: Accepted Manuscriptsupporting

confidence: 73%

Sources of dissolved organic carbon (DOC) in a mixed land use catchment (Exe, UK)

Ritson

Croft

Clark

et al. 2019

Science of The Total Environment

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“…For example, lowering of the water table due to increased evapotranspiration could increase O 2 availability providing the necessary conditions for degradation of recalcitrant phenolic compounds in the catotelm, which have been proposed to protect the global C bank in deep peat through inhibition of microbial heterotrophy according to the ‘enzyme latch' hypothesis31. However, recent studies have shown that temperature, water-table depth and perhaps even nutrient availability may control the strength of the enzyme latch, and that the response of phenolic compound degradation to climate drivers may be more complicated than originally hypothesized3233. The lack of a legacy warming effect in the surface peat after the first 13 months suggests that the warming treatment did not have a lasting effect—relevant to CO 2 and CH 4 production rates—on the microbial community or the peat itself.…”

Section: Discussionmentioning

confidence: 99%

Stability of peatland carbon to rising temperatures

et al. 2016

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Peatlands contain one-third of soil carbon (C), mostly buried in deep, saturated anoxic zones (catotelm). The response of catotelm C to climate forcing is uncertain, because prior experiments have focused on surface warming. We show that deep peat heating of a 2 m-thick peat column results in an exponential increase in CH4 emissions. However, this response is due solely to surface processes and not degradation of catotelm peat. Incubations show that only the top 20–30 cm of peat from experimental plots have higher CH4 production rates at elevated temperatures. Radiocarbon analyses demonstrate that CH4 and CO2 are produced primarily from decomposition of surface-derived modern photosynthate, not catotelm C. There are no differences in microbial abundances, dissolved organic matter concentrations or degradative enzyme activities among treatments. These results suggest that although surface peat will respond to increasing temperature, the large reservoir of catotelm C is stable under current anoxic conditions.

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“…We explored potential biogeochemical mechanisms for enhanced decomposition by comparing the chemical composition of leachates collected from fresh vegetation and peat core samples, using methods based on Pinsonneault et al. (). Leachates were prepared by soaking the samples in 60 ml DI water (1:3 sample:solution suspension) overnight ( c .…”

Section: Methodsmentioning

confidence: 99%

“…The chemical composition of leachates from different plant species varies due to significant variation in the secondary metabolites or “chemical defence mechanisms” employed by different species (Pinsonneault, Moore, Roulet, & Lapierre, ). These leachates typically comprise dissolved organic carbon (DOC, including humic acids and a range of polyphenolic compounds), and enzymes such as phenol oxidases (Beckett, Zavarzina, & Liers, ; Medvedeff et al., ; Naumova, Tomson, Zhmakova, Makarova, & Ovchinnikova, ; Zagoskina, Nikolaeva, Lapshin, Zavarzin, & Zavarzina, ).…”

Section: Introductionmentioning

confidence: 99%

Lichens: A limit to peat growth?

et al. 2018

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1. The fruticose lichens Cladina stellaris and Cladina rangiferina, form thick mats that can cover large areas of northern peatlands (above c. 50° latitude), including the extensive peatlands of the Hudson Bay Lowland (HBL) in Canada, where lichens may cover up to 50% of the landscape. Despite the abundance of lichens in northern peatlands, our understanding of their role within peatland ecosystems, and peat accumulation in particular, is limited.2. We investigate the potential effect of these mat-forming lichens on peat production and decomposition processes, using field data from an ombrogenous bog in the HBL and laboratory analyses. We hypothesize that (a) production in lichenshrub hummocks is less than in Sphagnum-shrub hummocks; (b) the decay of lichen litter is faster than that of Sphagnum moss, so the mass litter input to the peat profile is reduced; and (c) faster decomposition of the underlying peat is stimulated by lichen leachates, resulting in greater mass loss.3. We found that thick lichen mats alter vegetation composition in peatlands, reducing Sphagnum cover and inhibiting the growth of small shrubs. Coupled with low lichen productivity that is constrained by moisture conditions, production for lichen-shrub hummocks is significantly smaller than for Sphagnum-shrub hummocks, confirming hypothesis (a). Our data also support hypothesis (b), with chemical analyses of lichen mats and leachates from lichen mats indicating faster decay of lichens compared to Sphagnum moss, and therefore reduced mass litter input to the peat profile in lichen-dominated hummocks. Although we found no evidence to suggest leachates from lichens enhance decomposition processes in peatlands (hypothesis c), larger dry bulk densities for peat under lichen mats indicate a loss of structural integrity and potential collapse of the peat column. Synthesis.As production of new material added to the peat column is less in lichen-dominated hummocks, local peat accumulation slows or ceases, representing a potential temporary limit to peat growth. Our results highlight the importance of lichens as a vegetation feedback in peatland development, with thick mats probably constraining or reducing hummock height relative to adjacent, lichenfree hollows.

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Biodegradability of Vegetation-Derived Dissolved Organic Carbon in a Cool Temperate Ombrotrophic Bog

Cited by 47 publications

References 66 publications

Sources of dissolved organic carbon (DOC) in a mixed land use catchment (Exe, UK)

Sources of dissolved organic carbon (DOC) in a mixed land use catchment (Exe, UK)

Stability of peatland carbon to rising temperatures

Lichens: A limit to peat growth?

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