Episodic fluxes of methane from subarctic fens

Windsor, James; Moore, Tim R.; Roulet, Nigel T.

doi:10.4141/cjss92-037

Cited by 98 publications

(78 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…CH 4 emissions reached the peak in July (4.4 g CH 4 -C m −2 month −1 ) and held similar magnitude (3.8 g CH 4 -C m −2 month −1 ) in August even though the T a had dropped. Although it has been suggested that in some peatlands, WTH acts as a main control on CH 4 fluxes (Drösler et al, 2008;Knorr et al, 2009;Romanowicz et al, 1995;Roulet et al, 1993;Windsor et al, 1992), it has also been found that CH 4 emissions from wet soils (where the water table fluctuates within a small range near the surface) are highly dependent on T s because the oxidation in a shallow top soil is negligible (Jackowicz-Korczynski et al, 2010;Long et al, 2010;Olson et al, 2013;Rinne et al, 2007;Song et al, 2009). In our study, CH 4 emissions in the summer months were relative high even when the water table dropped to around 20 cm below the surface, likely because the peat maintained anaerobic conditions above the water table (as discussed in Hendriks et al, 2007).…”

Section: Ch 4 Exchange 441 Annual and Seasonal Ch 4 Budgetsmentioning

confidence: 99%

Annual greenhouse gas budget for a bog ecosystem undergoing restoration by rewetting

et al. 2017

View full text Add to dashboard Cite

Abstract. Many peatlands have been drained and harvested for peat mining, agriculture, and other purposes, which has turned them from carbon (C) sinks into C emitters. Rewetting of disturbed peatlands facilitates their ecological recovery and may help them revert to carbon dioxide (CO 2 ) sinks. However, rewetting may also cause substantial emissions of the more potent greenhouse gas (GHG) methane (CH 4 ). Our knowledge of the exchange of CO 2 and CH 4 following rewetting during restoration of disturbed peatlands is currently limited. This study quantifies annual fluxes of CO 2 and CH 4 in a disturbed and rewetted area located in the Burns Bog Ecological Conservancy Area in Delta, BC, Canada. Burns Bog is recognized as the largest raised bog ecosystem on North America's west coast. Burns Bog was substantially reduced in size and degraded by peat mining and agriculture. Since 2005, the bog has been declared a conservancy area, with restoration efforts focusing on rewetting disturbed ecosystems to recover Sphagnum and suppress fires. Using the eddy covariance (EC) technique, we measured year-round (16 June 2015 to 15 June 2016) turbulent fluxes of CO 2 and CH 4 from a tower platform in an area rewetted for the last 8 years. The study area, dominated by sedges and Sphagnum, experienced a varying water table position that ranged between 7.7 (inundation) and −26.5 cm from the surface during the study year. The annual CO 2 budget of the rewetted area was −179 ± 26.2 g CO 2 -C m −2 yr −1 (CO 2 sink) and the annual CH 4 budget was 17 ± 1.0 g CH 4 -C m −2 yr −1 (CH 4 source). Gross ecosystem productivity (GEP) exceeded ecosystem respiration (R e ) during summer months (June-August), causing a net CO 2 uptake. In summer, high CH 4 emissions (121 mg CH 4 -C m −2 day −1 ) were measured. In winter (December-February), while roughly equal magnitudes of GEP and R e made the study area CO 2 neutral, very low CH 4 emissions (9 mg CH 4 -C m −2 day −1 ) were observed. The key environmental factors controlling the seasonality of these exchanges were downwelling photosynthetically active radiation and 5 cm soil temperature. It appears that the high water table caused by ditch blocking suppressed R e . With low temperatures in winter, CH 4 emissions were more suppressed than R e . Annual net GHG flux from CO 2 and CH 4 expressed in terms of CO 2 equivalents (CO 2 eq.) during the study period totalled −22 ± 103.1 g CO 2 eq. m −2 yr −1 (net CO 2 eq. sink) and 1248 ± 147.6 g CO 2 eq. m −2 yr −1 (net CO 2 eq. source) by using 100-and 20-year global warming potential values, respectively. Consequently, the ecosystem was almost CO 2 eq. neutral during the study period expressed on a 100-year time horizon but was a significant CO 2 eq. source on a 20-year time horizon.

show abstract

Section: Ch 4 Exchange 441 Annual and Seasonal Ch 4 Budgetsmentioning

confidence: 99%

Annual greenhouse gas budget for a bog ecosystem undergoing restoration by rewetting

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Ebullition events have been found to be correlated with water table Iluctuations (Windsor et al, 1992) and atmospheric pressure Iluctuations (Matlson and Likens, 1990), where negative pressure changes stimulate bubble relcase.…”

Section: Sources Of Methanementioning

confidence: 99%

Methane dynamics of a northern boreal beaver pond

et al. 1999

View full text Add to dashboard Cite

“…In the discontinuous permafrost zone permafrost degradation may result in the partial or full disappearance of the permafrost aquiclude which can increase or decrease local hydraulic gradients depending on a variety of factors (Britton, 1957;Kane and Slaughter, 1973;Billings and Peterson, 1980;Woo, 1986;Jorgenson et al, 2001;Yoshikawa and Hinzman, 2003). Fen systems are particularly sensitive to water table f luctuations with studies showing rapid (i.e., on the order of days) increased CH 4 f luxes from fens when their water table elevations decrease Windsor et al, 1992). Flooded fens in interior Alaska were found to provide an increased CO 2 sink, whereas droughts reduced their carbon sink capacity and even turned them into small carbon sources (Chivers et al, 2009).…”

Section: Interior Alaska Wetlands and Hydrogeologymentioning

confidence: 99%

Sources and sinks of carbon in boreal ecosystems of interior Alaska: A review

Douglas

Jones

Hiemstra

et al. 2014

Elementa: Science of the Anthropocene

View full text Add to dashboard Cite

Boreal ecosystems store large quantities of carbon but are increasingly vulnerable to carbon loss due to disturbance and climate warming. The boreal region in Alaska and Canada, largely underlain by discontinuous permafrost, presents a challenging landscape for itemizing carbon sources and sinks in soil and vegetation. The roles of fire, forest succession, and the presence (or absence) of permafrost on carbon cycle, vegetation, and hydrologic processes have been the focus of multidisciplinary research in boreal ecosystems for the past 20 years. However, projections of a warming future climate, an increase in fire severity and extent, and the potential degradation of permafrost could lead to major landscape and carbon cycle changes over the next 20 to 50 years. To assist land managers in interior Alaska in adapting and managing for potential changes in the carbon cycle we developed this review paper by incorporating an overview of the climate, ecosystem processes, vegetation, and soil regimes. Our objective is to provide a synthesis of the most current carbon storage estimates and measurements to guide policy and land management decisions on how to best manage carbon sources and sinks. We surveyed estimates of aboveground and belowground carbon stocks for interior Alaska boreal ecosystems and summarized methane and carbon dioxide f luxes. These data have been converted into similar units to facilitate comparison across ecosystem compartments. We identify potential changes in the carbon cycle with climate change and human disturbance. A novel research question is how compounding disturbances affect carbon sources and sinks associated with boreal ecosystem processes. Finally, we provide recommendations to address the challenges facing land managers in efforts to manage carbon cycle processes. The results of this study can be used for carbon cycle management in other locations within the boreal biome which encompasses a broad distribution from 45° to 83° north.

show abstract

Episodic fluxes of methane from subarctic fens

Cited by 98 publications

References 19 publications

Annual greenhouse gas budget for a bog ecosystem undergoing restoration by rewetting

Annual greenhouse gas budget for a bog ecosystem undergoing restoration by rewetting

Methane dynamics of a northern boreal beaver pond

Sources and sinks of carbon in boreal ecosystems of interior Alaska: A review

Contact Info

Product

Resources

About