Seasonal contribution of CO2fluxes in the annual C budget of a northern bog

Roehm, C. L.; Roulet, Nigel T.

doi:10.1029/2002gb001889

Cited by 34 publications

(34 citation statements)

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“…A change in weather conditions and water table can easily convert a sink into a source and vice versa. This high interannual fluctuation of the CO 2 balances in organic soils, with years releasing CO 2 and others sequestering CO 2 , has been observed by many authors (Tuittila et al, 1999;Lloyd, 2001;Arneth et al, 2002;Roulet et al, 2007;Yli-Petays et al, 2007;Beetz et al, 2013). Natural bogs can be sources in the short term, but, on average over many years, they are sinks.…”

Section: Beyer and H Höper: Ghg Exchange Of Bogsmentioning

confidence: 73%

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Greenhouse gas exchange of rewetted bog peat extraction sites and a Sphagnum cultivation site in northwest Germany

Beyer

Höper

2015

Biogeosciences

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Abstract. During the last decades an increasing area of drained peatlands has been rewetted. Especially in Germany, rewetting is the principal treatment on cutover sites when peat extraction is finished. The objectives are bog restoration and the reduction of greenhouse gas (GHG) emissions. The first sites were rewetted in the 1980s. Thus, there is a good opportunity to study long-term effects of rewetting on greenhouse gas exchange, which has not been done so far on temperate cutover peatlands. Moreover, Sphagnum cultivating may become a new way to use cutover peatlands and agriculturally used peatlands as it permits the economical use of bogs under wet conditions. The climate impact of such measures has not been studied yet.We conducted a field study on the exchange of carbon dioxide, methane and nitrous oxide at three rewetted sites with a gradient from dry to wet conditions and at a Sphagnum cultivation site in NW Germany over the course of more than 2 years. Gas fluxes were measured using transparent and opaque closed chambers. The ecosystem respiration (CO 2 ) and the net ecosystem exchange (CO 2 ) were modelled at a high temporal resolution. Measured and modelled values fit very well together. Annually cumulated gas flux rates, net ecosystem carbon balances (NECB) and global warming potential (GWP) balances were determined.The annual net ecosystem exchange (CO 2 ) varied strongly at the rewetted sites (from −201.7±126.8 to 29.7 ± 112.7 g CO 2 -C m −2 a −1 ) due to differing weather conditions, water levels and vegetation. The Sphagnum cultivation site was a sink of CO 2 (−118.8±48.1 and −78.6±39.8 g CO 2 -C m −2 a −1 ). The annual CH 4 balances ranged between 16.2 ± 2.2 and 24.2 ± 5.0 g CH 4 -C m −2 a −1 at two inundated sites, while one rewetted site with a comparatively low water level and the Sphagnum farming site show CH 4 fluxes close to 0. The net N 2 O fluxes were low and not significantly different between the four sites. The annual NECB was between −185.5±126.9 and 49.9 ± 112.8 g CO 2 -C m −2 a −1 at the rewetted sites and −115.8±48.1 and −77±39.8 g CO 2 -C m −2 a −1 at the Sphagnum cultivating site. The annual GWP100 balances ranged from −280.5±465.2 to 644.5 ± 413.6 g CO 2 -eq. m −2 a −1 at the rewetted sites. In contrast, the Sphagnum farming site had a cooling impact on the climate in both years (−356.8±176.5 and −234.9±145.9 g CO 2 -C m −2 a −1 ). If the carbon exported through the harvest of the Sphagnum biomass and the additional CO 2 emission from the decay of the organic material is considered, the NECB and GWP100 balances are near neutral.Peat mining sites are likely to become net carbon sinks and a peat accumulating ("growing") peatland within 30 years of rewetting, but the GWP100 balance may still be positive. A recommended measure for rewetting is to achieve a water level of a few centimetres below ground.Sphagnum farming is a climate-friendly alternative to conventional commercial use of bogs. A year-round constant water level of a few centimetres below ground level should be mainta...

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Section: Beyer and H Höper: Ghg Exchange Of Bogsmentioning

confidence: 73%

“…For the remaining time period, the values are estimated or represent modelled fluxes (Byrne et al, 2004). This procedure can lead to false results (Roehm and Roulet, 2003), especially in temperate regions with mild winters. Most studies in restored peatlands are from recently rewetted sites.…”

mentioning

confidence: 99%

Greenhouse gas exchange of rewetted bog peat extraction sites and a Sphagnum cultivation site in northwest Germany

Beyer

Höper

2015

Biogeosciences

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“…This process may occur at any depth within the peat column. Currently, the amount of carbon dioxide sequestered by plant material is believed to be greater than that released into the atmosphere Moore et al, 2002;Roehm and Roulet, 2003) but, as we discuss further, that balance could change with a climateinduced change in the water-table elevation Blodau and Moore, 2003;Strack et al, 2004).…”

Section: Presence and Significance Of Trapped Gasmentioning

confidence: 87%

The hydrology of northern peatlands as affected by biogenic gas: current developments and research needs

Rosenberry

Glaser

Siegel

2006

Hydrological Processes

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Abstract:Recent research indicates that accumulation and release of biogenic gas from northern peatlands may substantially affect future climate. Sudden release of free-phase gas bubbles into the atmosphere may preclude the conversion of methane to carbon dioxide in the uppermost oxic layer of the peat, resulting in greater contribution of methane to the atmosphere than is currently estimated. The hydrology of these peatlands also affects and is affected by this process, especially when gas is released suddenly and episodically. Indirect hydrological evidence indicates that ebullitive gas releases are relatively frequent in some peatlands and time-averaged rates may be significantly greater than diffusive releases. Estimates of free-phase gas contained in peat have ranged from 0 to nearly 20% of the peat volume. Abrupt changes in the volume of gas may alter hydraulic gradients and movement of water and solutes in peat, which in turn could alter composition and fluxes of the gas. Peat surfaces also move vertically and horizontally in response to accumulation and release of free-phase gas. Future research should address the distribution, temporal variability, and relative significance of ebullition in peatlands and the consequent hydrological responses to these gas-emission events.

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“…Recent research in snow-covered temperate, alpine, and arctic environments shows that subniveal (under the snow) soil respiration can result in substantial fluxes of carbon dioxide (CO 2 ) through the snowpack (Sommerfeld et al 1993;Brooks et al 1996;Zimov et al 1996;Oechel et al 1997;Mariko et al 2000;McDowell et al 2000;Welker et al 2000;Roehm and Roulet 2003;Monson et al 2005Monson et al , 2006. The wintertime CO 2 flux through the snow can contribute in excess of 20% to the annual carbon budget (Winston et al 1997).…”

Section: Introductionmentioning

confidence: 99%

An automated system for continuous measurements of trace gas fluxes through snow: an evaluation of the gas diffusion method at a subalpine forest site, Niwot Ridge, Colorado

et al. 2009

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An experimental system for sampling trace gas fluxes through seasonal snowpack was deployed at a subalpine site near treeline at Niwot Ridge, Colorado. The sampling manifold was in place throughout the entire snow-covered season for continuous air sampling with minimal disturbance to the snowpack. A series of gases (carbon dioxide, water vapor, nitrous oxide, nitric oxide, ozone, volatile organic compounds) was determined in interstitial air withdrawn at eight heights in and above the snowpack at *hourly intervals. In this paper, carbon dioxide data from 2007 were used for evaluation of this technique. Ancillary data recorded inlcuded snow physical properties, i.e., temperature, pressure, and density. Various vertical concentration gradients were determined from the multiple height measurements, which allowed calculation of vertical gas fluxes through the snowpack using Fick's 1st law of diffusion. Comparison of flux results obtained from different height inlet combinations show that under most conditions fluxes derived from individual gradient intervals agree with the overall median of all data within a factor of 1.5. Winds were found to significantly influence gas concentration and gradients in the snowpack. Under the highest observed wind conditions, concentration gradients and calculated fluxes dropped to as low as 13% of non-wind conditions. Measured differential pressure amplitude exhibited a linear relationship with wind speed. This suggests that wind speed is a sound proxy for assessing advection transport in the snow. Neglecting the wind-pumping effect resulted in considerable underestimation of gas fluxes. An analysis of dependency of fluxes on wind speeds during a 3-week period in mid-winter determined that over this period actual gas fluxes were most likely 57% higher than Biogeochemistry (2009) 95:95-113 DOI 10.1007 fluxes calculated by the diffusion method, which omits the wind pumping dependency.

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Seasonal contribution of CO₂fluxes in the annual C budget of a northern bog

Cited by 34 publications

References 34 publications

Greenhouse gas exchange of rewetted bog peat extraction sites and a <i>Sphagnum</i> cultivation site in northwest Germany

Greenhouse gas exchange of rewetted bog peat extraction sites and a <i>Sphagnum</i> cultivation site in northwest Germany

The hydrology of northern peatlands as affected by biogenic gas: current developments and research needs

An automated system for continuous measurements of trace gas fluxes through snow: an evaluation of the gas diffusion method at a subalpine forest site, Niwot Ridge, Colorado

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Seasonal contribution of CO2fluxes in the annual C budget of a northern bog

Cited by 34 publications

References 34 publications

Greenhouse gas exchange of rewetted bog peat extraction sites and a &lt;i&gt;Sphagnum&lt;/i&gt; cultivation site in northwest Germany

Greenhouse gas exchange of rewetted bog peat extraction sites and a &lt;i&gt;Sphagnum&lt;/i&gt; cultivation site in northwest Germany

The hydrology of northern peatlands as affected by biogenic gas: current developments and research needs

An automated system for continuous measurements of trace gas fluxes through snow: an evaluation of the gas diffusion method at a subalpine forest site, Niwot Ridge, Colorado

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Seasonal contribution of CO₂fluxes in the annual C budget of a northern bog

Greenhouse gas exchange of rewetted bog peat extraction sites and a <i>Sphagnum</i> cultivation site in northwest Germany

Greenhouse gas exchange of rewetted bog peat extraction sites and a <i>Sphagnum</i> cultivation site in northwest Germany