Methane flux from drained northern peatlands: Effect of a persistent water table lowering on flux

<p>Fluctuations of water table depth (WTD) affect many processes in peatlands, such as vegetation development and emissions of greenhouse gases. Here, we present the OPtical TRApezoid Model (OPTRAM) as a new method for satellite-based monitoring of the temporal variation of WTD in peatlands. OPTRAM is based on the response of short-wave infrared reflectance to the vegetation water status. For five northern peatlands with long-term in-situ WTD records, and with diverse vegetation cover and hydrological regimes, we generate a suite of OPTRAM index time series using (a) different procedures to parametrise OPTRAM (peatland-specific manual vs. globally applicable automatic parametrisation in Google Earth Engine), and (b) different satellite input data (Landsat vs. Sentinel-2). The results based on the manual parametrisation of OPTRAM indicate a high correlation with in-situ WTD time-series for pixels with most suitable vegetation for OPTRAM application (mean Pearson correlation of 0.7 across sites), and we will present the performance differences when moving from a manual to an automatic procedure. Furthermore, for the overlap period of Landsat and Sentinel-2, which have different ranges and widths of short-wave infrared bands used for OPTRAM calculation, the impact of the satellite input data to OPTRAM will be analysed. Eventually, the challenge of merging different satellite missions in the derivation of OPTRAM time series will be explored as an important step towards a global application of OPTRAM for the monitoring of WTD dynamics in northern peatlands.</p>

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Methane flux: Water table relations in northern wetlands

Geophysical Research Letters ◽

10.1029/93gl00208 ◽

1993 ◽

Vol 20 (7) ◽

pp. 587-590 ◽

Cited By ~ 207

Author(s):

T. R. Moore ◽

N. T. Roulet

Keyword(s):

Water Table ◽

Methane Flux

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Methane Flux Influenced by Experimental Water Table Drawdown and Soil Warming in a Dry Boreal Continental Bog

Ecosystems ◽

10.1007/s10021-014-9795-z ◽

2014 ◽

Vol 17 (7) ◽

pp. 1271-1285 ◽

Cited By ~ 18

Author(s):

Tariq M. Munir ◽

Maria Strack

Keyword(s):

Water Table ◽

Methane Flux ◽

Soil Warming

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Patterned fens of western Labrador and adjacent Quebec: phytosociology, water chemistry, landform features, and dynamics of surface patterns

Canadian Journal of Botany ◽

10.1139/b88-327 ◽

1988 ◽

Vol 66 (12) ◽

pp. 2402-2418 ◽

Cited By ~ 21

Author(s):

David R. Foster ◽

George A. King ◽

Mary V. Santelmann

Keyword(s):

Water Chemistry ◽

Water Table ◽

Vegetation Type ◽

Open Water ◽

Differential Rate ◽

Peat Accumulation ◽

Surface Patterns ◽

Vegetation Water ◽

Northern Peatlands ◽

Pool Formation

The landforms, vegetation, water chemistry, and stratigraphy of four patterned fens (aapamires) in western Labrador and adjacent Quebec are described in a study investigating the origin and characteristics of surface patterns on northern peatlands. Phytosociological analysis by the relevé approach, in conjunction with analysis by TWINSPAN, is used to describe 11 floristic noda. The vegetational patterns are largely controlled by depth to the water table. Mire landforms discussed in detail include ice-push ridges, flarks and pools, peat ridges, and mire-margin hummocks. Water chemistry is typical of minerotrophic conditions, with pH ranging from 4.4 to 6.7 and calcium concentrations from 20 to 430 μiequiv. L−1. The water chemistry, vegetation, and landforms on the mires are compared with other studies from Labrador and circumboreal regions. Stratigraphic results and field observations support the theory that surface patterns on the mire develop slowly through the interplay of biological and hydrological processes, specifically differential rate of peat accumulation controlled by vegetation type and depth to water table. Pool formation apparently involves four steps: (i) gradual differentiation of shallow flarks on previously undifferentiated mire surface; (ii) expansion and deepening of flarks and development of ridges due to differential peat accumulation; (iii) degradation of flark vegetation into mud bottoms and open-water pools; and (iv) coalescence, continued expansion, and deepening of open-water areas. Hydrological controls over the rate and extent of pool formation are discussed as a probable explanation of the geographical distribution of patterned mires.

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Water Table Fluctuation in Peatlands Facilitates Fungal Proliferation, Impedes Sphagnum Growth and Accelerates Decomposition

Frontiers in Earth Science ◽

10.3389/feart.2020.579329 ◽

2021 ◽

Vol 8 ◽

Author(s):

Jinhyun Kim ◽

Line Rochefort ◽

Sandrine Hogue-Hugron ◽

Zuhair Alqulaiti ◽

Christian Dunn ◽

...

Keyword(s):

Organic Matter ◽

Microbial Community ◽

Water Table ◽

High Frequency ◽

Organic Matter Decomposition ◽

Anaerobic Conditions ◽

Water Table Fluctuation ◽

Decomposition Of Organic Matter ◽

Northern Peatlands ◽

Low Rate

Northern peatlands are substantial carbon sinks because organic matter in peat is highly stable due to the low rate of decomposition. Waterlogged anaerobic conditions induce accumulation of Sphagnum-derived phenolic compounds that inhibit peat organic matter decomposition, a mechanism referred to as the “enzymic latch”. Recent studies have predicted that the water table in northern peatlands may become unstable. We observed that such unstable water table levels can impede the development of Sphagnum mosses. In this study, we determined the effects of low and high frequency water table fluctuation regimes on Sphagnum growth and peat organic matter decomposition, by conducting a year-long mesocosm experiment. In addition, we conducted a molecular analysis to examine changes in abundance of fungal community which may play a key role in the decomposition of organic matter in peatlands. We found that rapid water table fluctuation inhibited the growth of Sphagnum due to fungal infection but stimulated decomposition of organic matter that may dramatically destabilize peatland carbon storage. Increased pH, induced by the fluctuation, may contribute to the enhanced activity of hydrolases in peat. We demonstrated that the water table fluctuation in peatlands impeded Sphagnum growth and accelerates decomposition due to fungal proliferation. Thus, we suggested that understanding the microbial community in the northern peatlands is essential for elucidating the possible changes in carbon cycle of peatland under the changing world.

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Effect of a lowered water table on nitrous oxide fluxes from northern peatlands

Nature ◽

10.1038/366051a0 ◽

1993 ◽

Vol 366 (6450) ◽

pp. 51-53 ◽

Cited By ~ 231

Author(s):

Pertti J. Martikainen ◽

Hannu Nykänen ◽

Patrick Crill ◽

Jouko Silvola

Keyword(s):

Nitrous Oxide ◽

Water Table ◽

Northern Peatlands

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The effect of forestry drainage practices on the emission of methane from northern peatlands

Canadian Journal of Forest Research ◽

10.1139/x95-055 ◽

1995 ◽

Vol 25 (3) ◽

pp. 491-499 ◽

Cited By ~ 52

Author(s):

Nigel T. Roulet ◽

T. R. Moore

Keyword(s):

Water Table ◽

Drainage Ditches ◽

Flux Data ◽

Northern Peatlands ◽

Forested Bog ◽

The Impact ◽

Forest Drainage

Methane (CH4) flux was measured from undrained, drained, and ditched portions of treed fen, forested bog, and treed bog sites in the Wally Creek experimental drainage site (near Cochrane, Ontario), from May to October 1991. Drainage for 7 years lowered the water table from between −21 and −49 cm to −41 and −93 cm at the three respective sites. Drainage resulted in a conversion of the peatlands from a CH4 source (0 to 15 mg CH4 •m−2 •d−1) to a small CH4 sink (0 to −0.4 mg CH4 •m−2 •d−1). In contrast, CH4 efflux from the ditches ranged from <5 to >400 mg CH4 m−2 •d−1. The flux data were used to estimate the impact of forest drainage practices on net CH4 emissions from a forest drainage complex. For the treed and forested bogs, there was a net increase in CH4 emissions where ditch spacing was closer than 38 m. Even with very close ditch spacing (>12 m), there was a net decrease in CH4 flux from the treed fen. The results of this study indicate that the combination of low antecedent CH4 fluxes from an undrained peatland, and moderate fluxes from the drainage ditches, will produce a net increase in CH4 emissions from forest drainage.

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The influence of water-table depth and pH on the spatial distribution of diatom species in peatlands of the Boreal Shield and Hudson Plains, Canada

Botany ◽

10.1139/cjb-2014-0138 ◽

2015 ◽

Vol 93 (2) ◽

pp. 57-74 ◽

Cited By ~ 15

Author(s):

Kathryn E. Hargan ◽

Kathleen M. Rühland ◽

Andrew M. Paterson ◽

Sarah A. Finkelstein ◽

James R. Holmquist ◽

...

Keyword(s):

Environmental Change ◽

Water Table ◽

Vegetation Type ◽

Diatom Assemblage ◽

Diatom Species ◽

Diatom Assemblages ◽

Poor Fen ◽

Influence Of Water ◽

Boreal Shield ◽

Northern Peatlands

Diatoms collected from 113 surface peat samples from the Boreal Shield and Hudson Plains show taxonomic distributions that are associated with macro-vegetation type, pH, and position relative to the water table, the main environmental variables measured in this study. The overall goal of our research was to determine the ecological distribution and response of diatoms to microhabitat conditions, and to assess the potential for diatoms to be applied as indicators of long-term environmental change in northern peatlands. Our results indicate that diatom assemblage composition was determined by both the broader peatland type (i.e., bog, rich and poor fens) and microhabitats within peatland formations (e.g., hummock, hollow). The diatom assemblages were primarily influenced by pH with the sites divided at a critical pH of 5.5, and secondarily by the depth to the water table. Acidic bog hollow and hummock microhabitats were species-poor and dominated almost exclusively by Eunotia paludosa A.Grunow and (or) Eunotia mucophila (H.Lange-Bertalot, M.Nörpel-Schempp & E.Alles) H.Lange-Bertalot. These acidophilic and aerophilic diatom species were associated with the narrow pH optima of the dominant Sphagnum L. species (e.g., Sphagnum fuscum (Schimp.) Klinggr., Sphagnum angustifolium (C.E.O.Jensen ex Russow) C.E.O.Jensen) found in these bog habitats. Rich and poor fen samples, which were less acidic, supported a more diverse diatom assemblage (>30 species) with greater variability in both diatom and bryophyte pH tolerances. The diatom assemblages recorded in the bogs and fens of our study are similar to those found in peatlands around the world, demonstrating that diatom species are very specialized to exist in these often harsh semi-aquatic environments. Diatoms from peatlands have great potential as biomonitors of environmental change in these important ecosystems.

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