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

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 emissions from an <i>Acacia</i> plantation on peatland in Sumatra, Indonesia

Biogeosciences Discussions ◽

10.5194/bgd-8-8269-2011 ◽

2011 ◽

Vol 8 (4) ◽

pp. 8269-8302 ◽

Cited By ~ 5

Author(s):

J. Jauhiainen ◽

A. Hooijer ◽

S. E. Page

Keyword(s):

Co2 Emissions ◽

Water Table ◽

Carbon Dioxide Emissions ◽

Co2 Emission ◽

Root Respiration ◽

Water Table Depth ◽

Rooting Zone ◽

Before And After ◽

Plantation Development ◽

Peat Surface

Abstract. Peat surface CO2 emission, groundwater table depth and peat temperature were monitored for two years along transects in an Acacia plantation on thick tropical peat (>4 m) in Sumatra, Indonesia. A total of 2300 emission measurements were taken at 144 locations. The autotrophic root respiration component of the CO2 emission was separated from heterotrophic emissions caused by peat oxidation in three ways: (i) by comparing CO2 emissions within and beyond the tree rooting zone, (ii) by comparing CO2 emissions with and without peat trenching (i.e. cutting any roots remaining in the peat beyond the tree rooting zone), and (iii) by comparing CO2 emissions before and after Acacia tree harvesting. On average, the contribution of root respiration to daytime CO2 emission is 21 % along transects in mature tree stands. At locations 0.5 m from trees this is up to 80 % of the total emissions, but it is negligible at locations more than 1.3 m away. This means that CO2 emission measurements well away from trees are free of any root respiration contribution and thus represent only peat oxidation emission. We find daytime mean annual CO2 emission from peat oxidation alone of 94 t ha−1 yr−1 at a mean water table depth of 0.8 m, and a minimum emission value of 80 t ha−1 yr−1 after correction for the effect of diurnal temperature fluctuations, which resulted in a 14.5 % reduction of the daytime emission. There is a positive correlation between mean long-term water table depths and peat oxidation CO2 emission. However, no such relation is found for instantaneous emission/water table depth within transects and it is clear that factors other than water table depth also affect peat oxidation and total CO2 emissions. The increase in the temperature of the surface peat due to plantation development may explain over 50 % of peat oxidation emissions.

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Post-fire carbon dioxide emissions from a peatland undergoing restoration

10.5194/egusphere-egu21-12193 ◽

2021 ◽

Author(s):

Rebekka Artz ◽

Mhairi Coyle ◽

Pete Gilbert ◽

Roxane Andersen ◽

Adrian Bass

Keyword(s):

Carbon Dioxide ◽

Carbon Dioxide Emissions ◽

Methane Flux ◽

Slope Aspect ◽

Unesco World Heritage ◽

Greenhouse Gas Flux ◽

Significant Damage ◽

Blanket Bog ◽

One Year ◽

The Uk

<p>In May 2019, a major wildfire event affected >60 km2 within the 4000 km2 Flow Country in Northern Scotland, UK, a flagship blanket bog peatland that is being considered for UNESCO World Heritage Status. While the fire itself created significant damage, it also led to an extraordinary and unique opportunity to compare burned and unburned landscape scale greenhouse gas flux and surface energy dynamics using sites that, crucially, have otherwise identical biophysical characteristics (slope, aspect, peat depth) and land management histories. Since September 2019, carbon dioxide and methane flux data have been collected alongside other micrometeorological variables. Due to the COVID-19 lockdown in the UK, the team had severe difficulties in maintaining the equipment and hence, only partial and preliminary data will be reported here to showcase the findings from this project to date. The data obtained so far suggest a post-fire reduction in net CO2 emissions for a period of one year since the beginning of our monitoring campaign.</p>

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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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