scholarly journals Seasonal methane emission from a boreal peatland in continuous permafrost zone of Northeast China: effects of active layer depth and vegetation

2012 ◽  
Vol 9 (6) ◽  
pp. 6751-6775
Author(s):  
Y. Miao ◽  
C. Song ◽  
L. Sun ◽  
X. Wang ◽  
H. Meng ◽  
...  
Keyword(s):  
Pore Water ◽  
Water Table ◽  
Active Layer ◽  
Northeast China ◽  
Abiotic Factors ◽  
Permafrost Zone ◽  
Layer Depth ◽  
Ch4 Emissions ◽  
Boreal Peatlands ◽  
Continuous Permafrost

Abstract. Boreal peatlands are significant natural sources of methane and especially vulnerable to abrupt climate change. However, the controlling factors of CH4 emission in boreal peatlands are still unclear. In this study, we investigated CH4 fluxes and abiotic factors (temperature, water table depth, active layer depth, and dissolved CH4 concentrations in pore water) during the growing seasons in 2010 and 2011 both in shrub-sphagnum- and sedge-dominated plant communities in continuous permafrost zone of Northeast China. The objective of our study was to examine the effects of vegetation types and abiotic factors on CH4 fluxes from a boreal peatland. In Eriophorum-dominated community, mean CH4 emissions were 1.015 and 0.801 mg m−2 h−1 in 2010 and 2011, respectively. CH4 fluxes (0.384 mg m−2 h−1) released from the shrub-mosses-dominated community were lower than that from Eriophorum-dominated community. Moreover, in Eriophorum-dominated community, CH4 fluxes showed a significant temporal pattern with a peak value in late August both in 2010 and 2011. However, no distinct seasonal variation was observed in the CH4 flux in the shrub-mosses-dominated community. Interestingly, both in Eriophorum- and shrub-sphagnum-dominated communities, CH4 fluxes did not show close correlation with air or soil temperature and water table depth, whereas CH4 emissions correlated well to active layer depth and CH4 concentration in soil pore water, especially in Eriophorum-dominated community. Our results suggest that CH4 released from the thawed CH4-rich permafrost layer may be a key factor controlling CH4 emissions in boreal peatlands, and highlight that CH4 fluxes vary with vegetation type in boreal peatlands.

scholarly journals Growing season methane emission from a boreal peatland in the continuous permafrost zone of Northeast China: effects of active layer depth and vegetation

2012 ◽  
Vol 9 (11) ◽  
pp. 4455-4464 ◽  
Author(s):  
Y. Miao ◽  
C. Song ◽  
L. Sun ◽  
X. Wang ◽  
H. Meng ◽  
...  
Keyword(s):  
Pore Water ◽  
Water Table ◽  
Active Layer ◽  
Northeast China ◽  
Abiotic Factors ◽  
Ch4 Emission ◽  
Layer Depth ◽  
Ch4 Emissions ◽  
Boreal Peatlands ◽  
Continuous Permafrost

Abstract. Boreal peatlands are significant natural sources of methane and especially vulnerable to abrupt climate change. However, the controlling factors of CH4 emission in boreal peatlands are still unclear. In this study, we investigated CH4 fluxes and abiotic factors (temperature, water table depth, active layer depth, and dissolved CH4 concentrations in pore water) during the growing seasons in 2010 and 2011 in both shrub-sphagnum- and sedge-dominated plant communities in the continuous permafrost zone of Northeast China. The objective of our study was to examine the effects of vegetation types and abiotic factors on CH4 fluxes from a boreal peatland. In an Eriophorum-dominated community, mean CH4 emissions were 1.02 and 0.80 mg m−2 h−1 in 2010 and 2011, respectively. CH4 fluxes (0.38 mg m−2 h−1) released from the shrub-mosses-dominated community were lower than that from Eriophorum-dominated community. Moreover, in the Eriophorum-dominated community, CH4 fluxes showed a significant temporal pattern with a peak value in late August in both 2010 and 2011. However, no distinct seasonal variation was observed in the CH4 flux in the shrub-mosses-dominated community. Interestingly, in both Eriophorum- and shrub-sphagnum-dominated communities, CH4 fluxes did not show close correlation with air or soil temperature and water table depth, whereas CH4 emissions correlated well to active layer depth and CH4 concentration in soil pore water, especially in the Eriophorum-dominated community. Our results suggest that CH4 released from the thawed CH4-rich permafrost layer may be a key factor controlling CH4 emissions in boreal peatlands, and highlight that CH4 fluxes vary with vegetation type in boreal peatlands. With increasing temperature in future climate patterns, increasing active layer depth and shifting plant functional groups in this region may have a significant effect on CH4 emission.

Annual Carbon Gas Emissions from a Boreal Peatland in Continuous Permafrost Zone, Northeast China

2016 ◽  
Vol 44 (5) ◽  
pp. 456-463 ◽  
Author(s):  
Yuqing Miao ◽  
Changchun Song ◽  
Xianwei Wang ◽  
Henan Meng ◽  
Li Sun ◽  
...  
Keyword(s):  
Northeast China ◽  
Permafrost Zone ◽  
Gas Emissions ◽  
Continuous Permafrost ◽  
Annual Carbon

scholarly journals Response of CH<sub>4</sub> emissions to moss removal and N addition in boreal peatland of northeast China

2014 ◽  
Vol 11 (17) ◽  
pp. 4809-4816 ◽  
Author(s):  
H. N. Meng ◽  
C. C. Song ◽  
Y. Q. Miao ◽  
R. Mao ◽  
X. W. Wang
Keyword(s):  
Northeast China ◽  
Interactive Effect ◽  
N Availability ◽  
N Addition ◽  
Atmospheric Methane ◽  
Ch4 Emissions ◽  
Growing Seasons ◽  
Boreal Peatlands ◽  
N Enrichment ◽  
Hinggan Mountain

Abstract. Boreal peatlands are an important natural source of atmospheric methane (CH4). Recently, boreal peatlands have been experiencing increased nitrogen (N) availability and decreased moss production. However, little is known about the interactive effect of moss and N availability on CH4 emissions in boreal peatlands. In this study, the effects of moss removal and N addition (6 g N m−2 yr−1) on CH4 emissions were examined during the growing seasons of 2011, 2012 and 2013 in a boreal peatland in the Great Hinggan Mountain of northeast China. Notably, the response of CH4 emissions to moss removal and N addition varied with experimental duration. Moss removal and N addition did not affect CH4 emissions in 2011 and 2012, but respectively reduced CH4 emissions by 50% and 66% in 2013. However, moss removal and N addition did not produce an interactive effect on CH4 emissions. Consequently, moss removal plus N addition had no effect on CH4 emissions in 2011 and 2012, but decreased CH4 emissions by 68% in 2013. These results suggest that the effects of moss removal and N enrichment on CH4 emissions are time-dependent in boreal peatlands, and also imply that increased N availability and decreased moss growth would independently inhibit CH4 emissions in the boreal peatlands of northeast China.

scholarly journals Wildfire overrides hydrological controls on boreal peatland methane emissions

2019 ◽  
Vol 16 (13) ◽  
pp. 2651-2660 ◽  
Author(s):  
Scott J. Davidson ◽  
Christine Van Beest ◽  
Richard Petrone ◽  
Maria Strack
Keyword(s):  
Water Table ◽  
Environmental Variables ◽  
Burn Severity ◽  
Radiative Effect ◽  
Production Potential ◽  
Fort Mcmurray ◽  
Ch4 Emissions ◽  
Boreal Peatlands ◽  
Ch4 Production ◽  
The Impact

Abstract. Boreal peatlands represent a globally important store of carbon, and disturbances such as wildfire can have a negative feedback to the climate. Understanding how carbon exchange and greenhouse gas (GHG) dynamics are impacted after a wildfire is important, especially as boreal peatlands may be vulnerable to changes in wildfire regime under a rapidly changing climate. However, given this vulnerability, there is very little in the literature on the impact such fires have on methane (CH4) emissions. This study investigated the effect of wildfire on CH4 emissions at a boreal fen near Fort McMurray, Alberta, Canada, that was partially burned by the Horse River Wildfire in 2016. We measured CH4 emissions and environmental variables (2017–2018) and CH4 production potential (2018) in two different microform types (hummocks and hollows) across a peat burn severity gradient (unburned (UB), moderately burned (MB), and severely burned (SB)). Results indicated a switch in the typical understanding of boreal peatland CH4 emissions. For example, emissions were significantly lower in the MB and SB hollows in both years compared to UB hollows. Interestingly, across the burned sites, hummocks had higher fluxes in 2017 than hollows at the MB and SB sites. We found typically higher emissions at the UB site where the water table was close to the surface. However, at the burned sites, no relationship was found between CH4 emissions and water table, even under similar hydrological conditions. There was also significantly higher CH4 production potential from the UB site than the burned sites. The reduction in CH4 emissions and production in the hollows at burned sites highlights the sensitivity of hollows to fire, removing labile organic material for potential methanogenesis. The previously demonstrated resistance of hummocks to fire also results in limited impact on CH4 emissions and likely faster recovery to pre-fire rates. Given the potential initial net cooling effect resulting from a reduction in CH4 emissions, it is important that the radiative effect of all GHGs following wildfire across peatlands is taken into account.

scholarly journals Dissolved organic carbon, major and trace element in peat pore water of sporadic, discontinuous and continuous permafrost zone of Western Siberia

2017 ◽  
Author(s):  
Tatiana V. Raudina ◽  
Sergey V. Loiko ◽  
Artyom Lim ◽  
Ivan V. Krickov ◽  
Liudmila S. Shirokova ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Pore Water ◽  
Western Siberia ◽  
Permafrost Zone ◽  
Discontinuous Permafrost ◽  
Peat Pore Water ◽  
Latitudinal Transect ◽  
Soil Solutions ◽  
Continuous Permafrost

Abstract. Mobilization of dissolved organic carbon (DOC) and related trace elements (TE) from the frozen peat to surface waters in the permafrost zone is one the major consequence of on-going permafrost thaw and active layer thickness (ALT) rise in high latitude regions. The interstitial soil solutions are efficient tracers of on-going bio-geochemical processes in the critical zone and can help to decipher the intensity of carbon and metals migration from the soil to the rivers and further to the ocean. To this end, we collected, across a 640 km latitudinal transect of sporadic to continuous permafrost zone of western Siberia peatlands, soil porewaters from 30 cm depth using suction cups and we analyzed DOC, DIC and 40 major and TE in 0.45 µm filtered fraction of 80 soil porewaters. Despite an expected decrease of the intensity of DOC and TE mobilization from the soil and vegetation litter to the interstitial fluids with the increase of the permafrost coverage, decrease in the annual temperature and ALT, the DOC and many major and trace element did not exhibit any distinct decrease in concentration along the latitudinal transect from 62.2° N to 67.4° N. The DOC demonstrated a maximum of concentration at 66° N, on the border of discontinuous/continuous permafrost zone, whereas the DOC concentration in peat soil solutions from continuous permafrost zone was equal or higher than that in sporadic/discontinuous permafrost zone. Moreover, a number of major (Ca, Mg) and trace (Al, Ti, Sr, Ga, REEs, Zr, Hf, Th) elements exhibited an increasing, not decreasing northward concentration trend. We hypothesize that the effect of temperature and thickness of the ALT are of secondary importance relative to the leaching capacity of peat which is in turn controlled by the water saturation of the peat core. The water residence time in peat pores also plays a role in enriching the fluids in some elements: the DOC, V, Cu, Pb, REE, Th were a factor of 1.5 to 2.0 higher in mounds relative to hollows. As such, it is possible that the time of reaction between the peat and downward infiltrating waters essentially controls the degree of peat pore-water enrichments in DOC and other solutes. A two-degree northward shift in the position of the permafrost boundaries may bring about a factor of 1.3 decrease in Ca, Mg, Sr, Al, Fe, Ti, Mn, Ni, Co, V, Zr, Hf, Th and REE porewater concentration in continuous and discontinuous permafrost zones, and a possible decrease in DOC, SUVA, Ca, Mg, Fe and Sr will not exceed 20 % of their actual values. The projected increase of ALT and vegetation density, northward migration of the permafrost boundary, or the change of hydrological regime are unlikely to modify chemical composition of peat pore water fluids larger than their natural variations within different micro-landscapes, i.e., within a factor of 2.

scholarly journals Large carbon cycle sensitivities to climate across a permafrost thaw gradient in subarctic Sweden

2019 ◽  
Vol 13 (2) ◽  
pp. 647-663 ◽  
Author(s):  
Kuang-Yu Chang ◽  
William J. Riley ◽  
Patrick M. Crill ◽  
Robert F. Grant ◽  
Virginia I. Rich ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Water Table ◽  
Active Layer ◽  
Carbon Budget ◽  
Climate Forcing ◽  
Biogeochemical Model ◽  
Ch4 Emissions ◽  
Permafrost Thaw ◽  
Thawing Permafrost ◽  
Subarctic Sweden

Abstract. Permafrost peatlands store large amounts of carbon potentially vulnerable to decomposition. However, the fate of that carbon in a changing climate remains uncertain in models due to complex interactions among hydrological, biogeochemical, microbial, and plant processes. In this study, we estimated effects of climate forcing biases present in global climate reanalysis products on carbon cycle predictions at a thawing permafrost peatland in subarctic Sweden. The analysis was conducted with a comprehensive biogeochemical model (ecosys) across a permafrost thaw gradient encompassing intact permafrost palsa with an ice core and a shallow active layer, partly thawed bog with a deeper active layer and a variable water table, and fen with a water table close to the surface, each with distinct vegetation and microbiota. Using in situ observations to correct local cold and wet biases found in the Global Soil Wetness Project Phase 3 (GSWP3) climate reanalysis forcing, we demonstrate good model performance by comparing predicted and observed carbon dioxide (CO2) and methane (CH4) exchanges, thaw depth, and water table depth. The simulations driven by the bias-corrected climate suggest that the three peatland types currently accumulate carbon from the atmosphere, although the bog and fen sites can have annual positive radiative forcing impacts due to their higher CH4 emissions. Our simulations indicate that projected precipitation increases could accelerate CH4 emissions from the palsa area, even without further degradation of palsa permafrost. The GSWP3 cold and wet biases for this site significantly alter simulation results and lead to erroneous active layer depth (ALD) and carbon budget estimates. Biases in simulated CO2 and CH4 exchanges from biased climate forcing are as large as those among the thaw stages themselves at a landscape scale across the examined permafrost thaw gradient. Future studies should thus not only focus on changes in carbon budget associated with morphological changes in thawing permafrost, but also recognize the effects of climate forcing uncertainty on carbon cycling.

scholarly journals Factors influencing CO<sub>2</sub> and CH<sub>4</sub> emissions from coastal wetlands in the Liaohe Delta, Northeast China

2015 ◽  
Vol 12 (4) ◽  
pp. 3469-3503 ◽  
Author(s):  
L. Olsson ◽  
S. Ye ◽  
X. Yu ◽  
M. Wei ◽  
K. W. Krauss ◽  
...  
Keyword(s):  
Water Table ◽  
Coastal Wetlands ◽  
Northeast China ◽  
Ecosystem Respiration ◽  
Soil Surface ◽  
Emission Rates ◽  
Ch4 Emission ◽  
Ch4 Emissions ◽  
Water Tables ◽  
Liaohe Delta

Abstract. Many factors are known to influence greenhouse gas emissions from coastal wetlands, but it is still unclear which factors are most important under field conditions when they are all acting simultaneously. The objective of this study was to assess the effects of water table, salinity, soil temperature and vegetation on CH4 emissions and ecosystem respiration (Reco) from five coastal wetlands in the Liaohe Delta, northeast China: two Phragmites australis (common reed) wetlands, two Suaeda salsa (sea blite) marshes and a rice (Oryza sativa) paddy. Throughout the growing season, the Suaeda wetlands were net CH4 sinks whereas the Phragmites wetlands and the rice paddy were net CH4 sources emitting 1.2–6.1 g CH4 m−2 y−1. The Phragmites wetlands emitted the most CH4 per unit area and the most CH4 relative to CO2. The main controlling factors for the CH4 emissions were water table, temperature and salinity. The CH4 emission was accelerated at high and constant (or managed) water tables and decreased at water tables below the soil surface. High temperatures enhanced CH4 emissions, and emission rates were consistently low (< 1 mg CH4 m−2 h) at soil temperatures <18 °C. At salinity levels > 18 ppt, the CH4 emission rates were always low (< 1 mg CH4 m−2 h−1) probably because methanogens were outcompeted by sulphate reducing bacteria. Saline Phragmites wetlands can, however, emit significant amounts of CH4 as CH4 produced in deep soil layers are transported through the air-space tissue of the plants to the atmosphere. The CH4 emission from coastal wetlands can be reduced by creating fluctuating water tables, including water tables below the soil surface, as well as by occasional flooding by high-salinity water. The effects of water management schemes on the biological communities in the wetlands must, however, be carefully studied prior to the management in order to avoid undesirable effects on the wetland communities.

scholarly journals Wildfire switches the typical understanding of boreal peatland methane emissions

2019 ◽  
Author(s):  
Scott J. Davidson ◽  
Christine Van Beest ◽  
Richard Petrone ◽  
Maria Strack
Keyword(s):  
Water Table ◽  
Environmental Variables ◽  
Burn Severity ◽  
Radiative Effect ◽  
Production Potential ◽  
Fort Mcmurray ◽  
Ch4 Emissions ◽  
Boreal Peatlands ◽  
Ch4 Production ◽  
The Impact

Abstract. Boreal peatlands represent a globally important store of carbon, and disturbances such as wildfire can have a negative feedback to the climate. Understanding how carbon exchange and greenhouse gas (GHG) dynamics are impacted after a wildfire is important, especially as boreal peatlands may be vulnerable to changes in wildfire regime under a rapidly changing climate. Yet, given this vulnerability, there is very little in the literature on the impact such fires have on methane (CH4) emissions. This study investigated the effect of wildfire on CH4 emissions at a boreal fen near Fort McMurray, AB, Canada, that was partially burned by the Horse River Wildfire in 2016. We measured CH4 emissions and environmental variables (2017–2018) and CH4 production potential (2018) in two different microform types (hummocks and hollows) across a burn severity gradient (unburned (UB), moderately burned (MB) and severely burned (SB)). Results indicated a switch in the typical understanding of boreal peatland CH4 emissions. For example, emissions were much lower in the MB and SB hollows in both years compared to UB hollows. Interestingly, across the burned sites, hummocks had higher fluxes in 2017 than hollows at the MB and SB sites. We found typically higher emissions at the UB site where the water table was close to the surface. However, at the burned sites, no relationship was found between CH4 emissions and water table, even under similar hydrological conditions. This further strengthens the argument on the overriding influence of fire. There was also significantly higher CH4 production potential from the UB site than the burned sites. The reduction in CH4 emissions and production in the hollows at burned sites highlights the sensitivity of hollows to fire, removing labile organic material for potential methanogenesis. The previously demonstrated resistance of hummocks to fire also results in limited impact to CH4 emissions and likely faster recovery to pre-fire rates. Given the potential initial net cooling effect resulting from a reduction in CH4 emissions, it is important that the radiative effect of all GHG following wildfire across peatlands is taken into account.

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