Methane flux: Water table relations in northern wetlands

T. R. Moore; N. T. Roulet

doi:10.1029/93gl00208

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

Global Biogeochemical Cycles ◽

10.1029/93gb01931 ◽

1993 ◽

Vol 7 (4) ◽

pp. 749-769 ◽

Cited By ~ 112

Author(s):

Nigel T. Roulet ◽

R. Ash ◽

W. Quinton ◽

Tim Moore

Keyword(s):

Water Table ◽

Methane Flux ◽

Northern Peatlands

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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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THE INFLUENCE OF WATER TABLE LEVELS ON METHANE AND CARBON DIOXIDE EMISSIONS FROM PEATLAND SOILS

Canadian Journal of Soil Science ◽

10.4141/cjss89-004 ◽

1989 ◽

Vol 69 (1) ◽

pp. 33-38 ◽

Cited By ~ 293

Author(s):

T. R. MOORE ◽

R. KNOWLES

Keyword(s):

Carbon Dioxide ◽

Water Table ◽

Carbon Dioxide Emissions ◽

Methane Flux ◽

Organic Soils ◽

Molar Ratios ◽

Microbial Characteristics ◽

Influence Of Water ◽

Peat Surface ◽

Logarithmic Relationship

The evolution of carbon dioxide and methane was measured from laboratory columns packed with surface (0–30 cm) materials representing a fen, a bog and a swamp and with varying water tables and treated with water containing 10 mg L−1 dissolved organic carbon. Carbon dioxide evolution increased in a linear relationship as the water table was lowered, ranging from 0.3–0.5 g CO2 m−2 d−1 to 6.6–9.4 g CO2 m−2 d−1 for the water table at 10 cm above and 70 cm below the peat surface, respectively. Methane evolution decreased in a logarithmic relationship as the water table was lowered. The fen showed the highest rates of methane flux (28 mg CH4 m−2 d−1 when inundated) and the bog the lowest (0.7 mg CH4 m−2 d−1 when inundated). These differences appeared to be related to the acidity of the soils and their microbial characteristics. Molar ratios of carbon dioxide:methane evolution increased from 4 to 173 under inundated conditions to > 2500 when the water table was at a depth of 70 cm. Key words: Methane, carbon dioxide, water table, organic soils, peatlands

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Carbon Dioxide and Methane Flux Response and Recovery From Drought in a Hemiboreal Ombrotrophic Fen

Frontiers in Earth Science ◽

10.3389/feart.2020.562401 ◽

2021 ◽

Vol 8 ◽

Author(s):

J. B Keane ◽

S. Toet ◽

P. Ineson ◽

P. Weslien ◽

J. E. Stockdale ◽

...

Keyword(s):

Climate Change ◽

Carbon Dioxide ◽

Water Table ◽

Net Ecosystem Exchange ◽

Open Water ◽

Calluna Vulgaris ◽

Methane Flux ◽

High Water ◽

Peat Bogs ◽

Flux Response

Globally peatlands store 500 Gt carbon (C), with northern blanket bogs accumulating 23 g C m−2 y−1 due to cool wet conditions. As a sink of carbon dioxide (CO2) peat bogs slow anthropogenic climate change, but warming climate increases the likelihood of drought which may reduce net ecosystem exchange (NEE) and increase soil respiration, tipping C sinks to sources. High water tables make bogs a globally important source of methane (CH4), another greenhouse gas (GHG) with a global warming potential (GWP) 34 times that of CO2. Warming may increase CH4 emissions, but drying may cause a reduction. Predicted species composition changes may also influence GHG balance, due to different traits such as erenchyma, e.g., Eriophorum vaginatum (eriophorum) and non-aerenchymatous species, e.g., Calluna vulgaris (heather). To understand how these ecosystems will respond to climate change, it is vital to measure GHG responses to drought at the species level. An automated chamber system, SkyLine2D, measured NEE and CH4 fluxes near-continuously from an ombrotrophic fen from August 2017 to September 2019. Four ecotypes were identified: sphagnum (Sphagnum spp), eriophorum, heather and water, hypothesizing that fluxes would significantly differ between ecotypes. The 2018 drought allowed comparison of fluxes between drought and non-drought years (May to September), and their recovery the following year. Methane emissions differed between ecotypes (p < 0.02), ordered high to low: eriophorum > sphagnum > water > heather, ranging from 23 to 8 mg CH4-C m−2 d−1. Daily NEE was similar between ecotypes (p > 0.7), but under 2018 drought conditions all ecotypes were greater sources of CO2 compared to 2019, losing 1.14 g and 0.24 g CO2-C m−2 d−1 respectively (p < 0.001). CH4 emissions were ca. 40% higher during 2018 than 2019, 17 mg compared to 12 mg CH4-C m−2 d−1 (p < 0.0001), and fluxes exhibited hysteresis with water table depth. A lag of 84–88 days was observed between rising water table and increased CH4 emissions. A significant interaction between ecotype and year showed fluxes from open water did not return to pre-drought levels. Our findings suggest that short-term drought may lead to a net increase in C emissions from northern wetlands.

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Microtopography and methane flux in boreal peatlands, northern Ontario, Canada

Canadian Journal of Botany ◽

10.1139/b93-122 ◽

1993 ◽

Vol 71 (8) ◽

pp. 1056-1063 ◽

Cited By ~ 89

Author(s):

J. Bubier ◽

A. Costello ◽

T. R. Moore ◽

N. T. Roulet ◽

K. Savage

Keyword(s):

Water Table ◽

Methane Flux ◽

Surface Layers ◽

Secondary Importance ◽

Northern Ontario ◽

Boreal Peatlands ◽

Poor Fen ◽

Average Water ◽

Peat Surface ◽

Static Chamber Technique

Fluxes of methane were measured by a static chamber technique at hummock, hollow, and lawn microtopographic locations in 12 peatland sites near Cochrane, northern Ontario, from May to October 1991. Average fluxes (mg∙m−2∙d−1) were 2.3 (SD = 1.9) at hummocks, 44.4 (SD = 49.0) at hollows, and 15.6 (SD = 12.9) at lawns. Methane flux was negatively correlated with average water table position based on the 36 locations (r2 = 0.649, p < 0.001), with hummocks having a smaller flux than hollows or lawns, where the water table depth was < 25 cm. Peat samples from a bog hummock and hollow failed to produce methane during anaerobic incubations in the laboratory; samples from a poor fen hollow produced < 1.4 μg∙g−1∙d−1. The production decreased with depth but was greater than the rates observed during the incubation of samples from an adjacent hummock. Rates of methane consumption during aerobic incubations ranged from 1 to 55 μg∙g−1∙d−1 and were greatest in the surface layers and decreased with depth. Differences in methane emissions between hummocks and hollows appear to be controlled primarily by greater methane production rates in hollows compared with hummocks. Of secondary importance are the capacity of the peat profiles to consume methane during its transport to the peat surface and warmer temperatures at the water table beneath hollows compared with hummocks. Key words: peatlands, methane, bog, fen, decomposition.

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