Geochemical controls on anaerobic organic matter decomposition in a northern peatland

Beer, Julia; Lee, Kern; Whiticar, Michael J.; Blodau, Christian

doi:10.4319/lo.2008.53.4.1393

Cited by 75 publications

(94 citation statements)

References 57 publications

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“…9, Table 2) controls the decline in overall decomposition rate of submerged peat as a function of depth below the water table. In situ biogeochemical studies indicate that decomposition rates in deep peat are limited by lack of solute transport (e.g., Beer and Blodau, 2007;Beer et al, 2008). In HPM this is represented as a rate multiplier that declines exponentially with distance below the simulated water table.…”

Section: Decompositionmentioning

confidence: 99%

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A new model of Holocene peatland net primary production, decomposition, water balance, and peat accumulation

et al. 2010

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Abstract. Peatland carbon and water cycling are tightly coupled, so dynamic modeling of peat accumulation over decades to millennia should account for carbon-water feedbacks. We present initial results from a new simulation model of long-term peat accumulation, evaluated at a wellstudied temperate bog in Ontario, Canada. The Holocene Peat Model (HPM) determines vegetation community composition dynamics and annual net primary productivity based on peat depth (as a proxy for nutrients and acidity) and water table depth. Annual peat (carbon) accumulation is the net balance above-and below-ground productivity and litter/peat decomposition -a function of peat hydrology (controlling depth to and degree of anoxia). Peat bulk density is simulated as a function of degree of humification, and affects the water balance through its influence on both the growth rate of the peat column and on peat hydraulic conductivity and the capacity to shed water. HPM output includes both time series of annual carbon and water fluxes, peat height, and water table depth, as well as a final peat profile that can be "cored" and compared to field observations of peat age and macrofossil composition. A stochastic 8500-yr, annual precipitation time series was constrained by a published Holocene climate reconstruction for southern Québec. HPM simulated 5.4 m of peat accumulation (310 kg C m −2 ) over 8500 years, 6.5% of total NPP over the period. Vascular plant functional types accounted for 65% of total NPP over 8500 years but only 35% of the final (contemporary) peat mass. Simulated age-depth Correspondence to: S. Frolking (steve.frolking@unh.edu) and carbon accumulation profiles were compared to a radiocarbon dated 5.8 m, c.9000-yr core. The simulated core was younger than observations at most depths, but had a similar overall trajectory; carbon accumulation rates were generally higher in the simulation and were somewhat more variable than observations. HPM results were sensitive to centuryscale anomalies in precipitation, with extended drier periods (precipitation reduced ∼10%) causing the peat profile to lose carbon (and height), despite relatively small changes in NPP.

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Section: Decompositionmentioning

confidence: 99%

“…In the saturated zone below the water table, the multiplier, f 2 , drops exponentially with depth below the water table (ẑ = z − z WT ;ẑ > 0), representing effects on decomposition rates of water residence time (end-product accumulation, extreme anoxia; Beer and Blodau, 2007;Beer et al, 2008), as…”

Section: Carbon Balance Equationsmentioning

confidence: 99%

A new model of Holocene peatland net primary production, decomposition, water balance, and peat accumulation

et al. 2010

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“…Here, anaerobic decomposition proceeds at a rate of only ∼1 % or less of the rate in the acrotelm (Clymo, 1984;Frolking et al, 2001;Beer et al, 2008). Controls on decomposition rates are the plant community type (e.g.…”

Section: T Broder Et Al: Peat Decomposition Records In Three Pristimentioning

confidence: 99%

“…changes in the molecular structure of organic matter, based on an increase in the relative abundance of recalcitrant moieties such as aliphatics or aromatics compared to labile fractions, such as carbohydrates (e.g. Beer et al, 2008;Kalbitz et al, 1999;Cocozza et al, 2003). More decomposed peat was further reported to release less DOC than undecomposed peat (Biester et al, 2006;Kalbitz and Geyer, 2002).…”

Section: T Broder Et Al: Peat Decomposition Records In Three Pristimentioning

confidence: 99%

Peat decomposition records in three pristine ombrotrophic bogs in southern Patagonia

et al. 2012

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Abstract. Ombrotrophic bogs in southern Patagonia have been examined with regard to paleoclimatic and geochemical research questions but knowledge about organic matter decomposition in these bogs is limited. Therefore, we examined peat humification with depth by Fourier Transformed Infrared (FTIR) measurements of solid peat, C/N ratio, and δ 13 C and δ 15 N isotope measurements in three bog sites. Peat decomposition generally increased with depth but distinct small scale variation occurred, reflecting fluctuations in factors controlling decomposition. C/N ratios varied mostly between 40 and 120 and were significantly correlated (R 2 > 0.55, p < 0.01) with FTIR-derived humification indices. The degree of decomposition was lowest at a site presently dominated by Sphagnum mosses. The peat was most strongly decomposed at the driest site, where currently peat-forming vegetation produced less refractory organic material, possibly due to fertilizing effects of high sea spray deposition. Decomposition of peat was also advanced near ash layers, suggesting a stimulation of decomposition by ash deposition. Values of δ 13 C were 26.5 ± 2 ‰ in the peat and partly related to decomposition indices, while δ 15 N in the peat varied around zero and did not consistently relate to any decomposition index. Concentrations of DOM partly related to C/N ratios, partly to FTIR derived indices. They were not conclusively linked to the decomposition degree of the peat. DOM was enriched in 13 C and in 15 N relative to the solid phase probably due to multiple microbial modifications and recycling of N in these N-poor environments. In summary, the depth profiles of C/N ratios, δ 13 C values, and FTIR spectra seemed to reflect changes in environmental conditions affecting decomposition, such as bog wetness, but were dominated by site specific factors, and are further influenced by ash deposition and possibly by sea spray input.

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“…Although intrinsic decomposability of SOM cannot be addressed directly, useful indicators of the latter are the relative abundances of labile and recalcitrant C moieties, which shift towards progressively higher proportions of the recalcitrant C with decomposition (Beer et al, 2008;Tfaily et al, 2014) and result in selective enrichment and depletion of specific functionalities McAnallen et al, 2017). It is important to recognize that during peat formation, most of the net primary production contained in the initial mass of plant residues are lost due to mineralization, and only 10-20 % is transformed and accumulated as peat in the watersaturated zone of a peat bog or fen (Clymo, 1984).…”

Section: Introductionmentioning

confidence: 99%

Peat decomposability in managed organic soils in relation to land use, organic matter composition and temperature

et al. 2018

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Abstract. Organic soils comprise a large yet fragile carbon (C) store in the global C cycle. Drainage, necessary for agriculture and forestry, triggers rapid decomposition of soil organic matter (SOM), typically increasing in the order forest < grassland < cropland. However, there is also large variation in decomposition due to differences in hydrological conditions, climate and specific management. Here we studied the role of SOM composition on peat decomposability in a variety of differently managed drained organic soils. We collected a total of 560 samples from 21 organic cropland, grassland and forest soils in Switzerland, monitored their CO 2 emission rates in lab incubation experiments over 6 months at two temperatures (10 and 20 • C) and related them to various soil characteristics, including bulk density, pH, soil organic carbon (SOC) content and elemental ratios (C / N, H / C and O / C). CO 2 release ranged from 6 to 195 mg CO 2 -C g −1 SOC at 10 • C and from 12 to 423 mg g −1 at 20 • C. This variation occurring under controlled conditions suggests that besides soil water regime, weather and management, SOM composition may be an underestimated factor that determines CO 2 fluxes measured in field experiments. However, correlations between the investigated chemical SOM characteristics and CO 2 emissions were weak. The latter also did not show a dependence on land-use type, although peat under forest was decomposed the least. High CO 2 emissions in some topsoils were probably related to the accrual of labile crop residues. A comparison with published CO 2 rates from incubated mineral soils indicated no difference in SOM decomposability between these soil classes, suggesting that accumulation of recent, labile plant materials that presumably account for most of the evolved CO 2 is not systematically different between mineral and organic soils. In our data set, temperature sensitivity of decomposition (Q 10 on average 2.57 ± 0.05) was the same for all land uses but lowest below 60 cm in croplands and grasslands. This, in turn, indicates a relative accumulation of recalcitrant peat in topsoils.

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Geochemical controls on anaerobic organic matter decomposition in a northern peatland

Cited by 75 publications

References 57 publications

A new model of Holocene peatland net primary production, decomposition, water balance, and peat accumulation

A new model of Holocene peatland net primary production, decomposition, water balance, and peat accumulation

Peat decomposition records in three pristine ombrotrophic bogs in southern Patagonia

Peat decomposability in managed organic soils in relation to land use, organic matter composition and temperature

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