scholarly journals Reduced Carbon Dioxide Sink and Methane Source under Extreme Drought Condition in an Alpine Peatland

2018 ◽  
Vol 10 (11) ◽  
pp. 4285 ◽  
Author(s):  
Xiaoming Kang ◽  
Liang Yan ◽  
Lijuan Cui ◽  
Xiaodong Zhang ◽  
Yanbin Hao ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Growth Stage ◽  
Carbon Budget ◽  
Carbon Sink ◽  
Ecosystem Respiration ◽  
Soil Depth ◽  
Extreme Drought ◽  
Sink Activity ◽  
Zoigê Plateau ◽  
Zoige Plateau

Potential changes in both the intensity and frequency of extreme drought events are vital aspects of regional climate change that can alter the distribution and dynamics of water availability and subsequently affect carbon cycles at the ecosystem level. The effects of extreme drought events on the carbon budget of peatland in the Zoige plateau and its response mechanisms were studied using an in-field controlled experimental method. The results indicated that the peatland ecosystem of the Zoige plateau functioned as a carbon sink while under the control (CK) or extreme drought (D) treatment throughout the entire growing season. Maximum fluxes of methane (CH4) emissions and the weakest carbon sink activity from this ecosystem were in the early growth stage, the most powerful carbon sink activity was during the peak growth stage, while the absorption sink activity of carbon dioxide (CO2) and CH4 was present during the senescence stage. Extreme drought reduced the gross primary productivity (GPP) and ecosystem respiration (Re) of the peatland ecosystem by 14.5% and 12.6%, respectively (p < 0.05) and the net ability to store carbon was reduced by 11.3%. Overall, the GPP was highly sensitive to extreme drought. Moreover, extreme drought significantly reduced the CH4 fluxes of the ecosystem and even changed the peatland from a CH4 emission source to a CH4 sink. Subsequent to drought treatment, extreme drought was also shown to have a carry-over effect on the carbon budget of this ecosystem. Soil water content and soil temperature were the main driving factors of carbon budget change in the peatland of the Zoige plateau, but with the increase in soil depth, these driving forces were decreased. The findings indicated that frequent extreme drought events in the future might reduce the net carbon sink function of peatland areas, with an especially strong influence on CO2.

scholarly journals Carbon dioxide fluxes over an ancient broadleaved deciduous woodland in southern England

2011 ◽  
Vol 8 (6) ◽  
pp. 1595-1613 ◽  
Author(s):  
M. V. Thomas ◽  
Y. Malhi ◽  
K. M. Fenn ◽  
J. B. Fisher ◽  
M. D. Morecroft ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Primary Productivity ◽  
Management Practices ◽  
Net Primary Productivity ◽  
Deciduous Forest ◽  
Carbon Sink ◽  
Ecosystem Respiration ◽  
Flux Chamber ◽  
Southern England ◽  
Temperate Deciduous

Abstract. We present results from a study of canopy-atmosphere fluxes of carbon dioxide from 2007 to 2009 above a site in Wytham Woods, an ancient temperate broadleaved deciduous forest in southern England. Gap-filled net ecosystem exchange (NEE) data were partitioned into gross primary productivity (GPP) and ecosystem respiration (Re) and analysed on daily, monthly and annual timescales. Over the continuous 24 month study period annual GPP was estimated to be 21.1 Mg C ha−1 yr−1 and Re to be 19.8 Mg C ha−1 yr−1; net ecosystem productivity (NEP) was 1.2 Mg C ha−1 yr−1. These estimates were compared with independent bottom-up estimates derived from net primary productivity (NPP) and flux chamber measurements recorded at a plot within the flux footprint in 2008 (GPP = 26.5 ± 6.8 Mg C ha−1 yr−1, Re = 24.8 ± 6.8 Mg C ha−1 yr−1, biomass increment = ~1.7 Mg C ha−1 yr−1). Over the two years the difference in seasonal NEP was predominantly caused by changes in ecosystem respiration, whereas GPP remained similar for equivalent months in different years. Although solar radiation was the largest influence on daily values of CO2 fluxes (R2 = 0.53 for the summer months for a linear regression), variation in Re appeared to be driven by temperature. Our findings suggest that this ancient woodland site is currently a substantial sink for carbon, resulting from continued growth that is probably a legacy of past management practices abandoned over 40 years ago. Our GPP and Re values are generally higher than other broadleaved temperate deciduous woodlands and may represent the influence of the UK's maritime climate, or the particular species composition of this site. The carbon sink value of Wytham Woods supports the protection and management of temperate deciduous woodlands (including those managed for conservation rather than silvicultural objectives) as a strategy to mitigate atmospheric carbon dioxide increases.

scholarly journals Small waterbodies reduce the carbon sink of a polygonal tundra landscape

2021 ◽  
Author(s):  
Lutz Beckebanze ◽  
Zoé Rehder ◽  
David Holl ◽  
Charlotta Mirbach ◽  
Christian Wille ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Budget ◽  
Carbon Sink ◽  
Open Water ◽  
Methane Emissions ◽  
The Arctic ◽  
Sink Strength ◽  
Small Waterbodies ◽  
Methane Fluxes ◽  
The Impact

Abstract. Arctic permafrost landscapes have functioned as a global carbon sink for millennia. These landscapes are very heterogeneous, and the omnipresent waterbodies are a carbon source within them. Yet, only a few studies focus on the impact of these waterbodies on the landscape carbon budget. We compare carbon dioxide and methane fluxes from small waterbodies to fluxes from the surrounding tundra using eddy covariance measurements from a tower located between a large pond and semi-terrestrial vegetated tundra. When taking the open-water areas of small waterbodies into account, the carbon dioxide sink strength of the landscape was reduced by 11 %. While open-water methane emissions were similar to the tundra emissions, some parts of the studied pond's shoreline exhibited much higher emissions, underlining the high spatial variability of methane emissions. We conclude that gas fluxes from small waterbodies can contribute significantly to the carbon budget of arctic tundra landscapes. Consequently, changes in arctic hydrology and the concomitant changes in the waterbody distribution may substantially impact the overall carbon budget of the Arctic.

scholarly journals Seasonal variations in carbon dioxide exchange in an alpine wetland meadow on the Qinghai-Tibetan Plateau

2010 ◽  
Vol 7 (4) ◽  
pp. 1207-1221 ◽  
Author(s):  
L. Zhao ◽  
J. Li ◽  
S. Xu ◽  
H. Zhou ◽  
Y. Li ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Tibetan Plateau ◽  
Carbon Sink ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Carbon Dioxide Exchange ◽  
Research Station ◽  
Rain Event ◽  
Area Index ◽  
Alpine Wetland

Abstract. Alpine wetland meadow could functions as a carbon sink due to it high soil organic content and low decomposition. However, the magnitude and dynamics of carbon stock in alpine wetland ecosystems are not well quantified. Therefore, understanding how environmental variables affect the processes that regulate carbon fluxes in alpine wetland meadow on the Qinghai-Tibetan Plateau is critical. To address this issue, Gross Primary Production (GPP), Ecosystem Respiration (Reco), and Net Ecosystem Exchange (NEE) were examined in an alpine wetland meadow using the eddy covariance method from October 2003 to December 2006 at the Haibei Research Station of the Chinese Academy of Sciences. Seasonal patterns of GPP and Reco were closely associated with leaf area index (LAI). The Reco showed a positive exponential to soil temperature and relatively low Reco occurred during the non-growing season after a rain event. This result is inconsistent with the result observed in alpine shrubland meadow. In total, annual GPP were estimated at 575.7, 682.9, and 630.97 g C m−2 in 2004, 2005, and 2006, respectively. Meanwhile, the Reco were equal to 676.8, 726.4, 808.2 g C m−2, and thus the NEE were 101.1, 44.0 and 173.2 g C m−2. These results indicated that the alpine wetland meadow was a moderately source of carbon dioxide (CO2). The observed carbon dioxide fluxes in the alpine wetland meadow were higher than other alpine meadow such as Kobresia humilis meadow and shrubland meadow.

scholarly journals Effects of a windthrow disturbance on the carbon balance of a broadleaf deciduous forest in Hokkaido, Japan

2015 ◽  
Vol 12 (13) ◽  
pp. 10425-10468
Author(s):  
K. Yamanoi ◽  
Y. Mizoguchi ◽  
H. Utsugi
Keyword(s):  
Forest Management ◽  
Carbon Balance ◽  
Carbon Budget ◽  
Deciduous Forest ◽  
Carbon Sink ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
White Birch ◽  
Eddy Covariance Method ◽  
Area Index

Abstract. Forests play an important role in the terrestrial carbon budget, with most being in a carbon sequestration stage. The net carbon releases that occur result from forest disturbance, and windthrow is a typical disturbance event affecting the forest carbon balance in eastern Asia. The carbon budget has been measured using the eddy covariance method in a deciduous broadleaf forest (Japanese white birch, Japanese oak, and castor aralia) in Hokkaido, where accidental damage by the strong typhoon, Songda, in 2004 occurred. We also used the biometrical method to demonstrate the carbon flow within the forest in detail. Damaged trees amounted to 40 % of all trees, and they remained on site where they were not extracted by forest management. Gross primary production (GPP), ecosystem respiration (Re), and net ecosystem production were 1350, 975, and 375 g C m−2 yr−1 before the disturbance and 1262, 1359, and −97 g C m−2 yr−1 2 years after the disturbance, respectively. Before the disturbance, the forest was an evident carbon sink, and it subsequently transformed to net a carbon source. Because of light enrichment at the forest floor, the leaf area index and biomass of the undergrowth (Sasa kurilensis and S. senanensis) increased by factors of 2.4 and 1.7, respectively, in 3 years subsequent to the disturbance. The photosynthesis of Sasa increased rapidly and contributed to the total GPP after the disturbance. The annual GPP only decreased by 6 % just after the disturbance. On the other hand, the annual Re increased by 39 % mainly because of the decomposition of residual coarse-wood debris. The carbon balance after the disturbance was controlled by the new growth and the decomposition of residues. The forest management, which resulted in the dead stands remaining at the study site, strongly affected the carbon budget over the years. When comparing the carbon uptake efficiency at the study site with that at others, including those with various kinds of disturbances, we emphasized the importance of forest management as well as disturbance type in the carbon budget.

scholarly journals Carbon accumulation in a drained boreal bog was decreased but not stopped by seasonal drought

2018 ◽  
Author(s):  
Kari Minkkinen ◽  
Paavo Ojanen ◽  
Timo Penttilä ◽  
Mika Aurela ◽  
Tuomas Laurila ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Sink ◽  
Ecosystem Respiration ◽  
Carbon Accumulation ◽  
Process Models ◽  
Litter Production ◽  
Severe Drought ◽  
Tree Stand ◽  
Drought Period ◽  
Soil C

Abstract. Drainage of peatlands is expected to turn these ecosystems to carbon sources to the atmosphere. We measured carbon dynamics of a drained forested peatland in southern Finland over four years, including one with severe drought during growing season. Net ecosystem exchange (NEE) of carbon dioxide (CO2) was measured with eddy covariance method from a mast above the forest. Soil and forest floor CO2 and methane (CH4) fluxes were measured from the strips and from ditches with closed chambers. Biomasses and litter production were sampled, and soil subsidence was measured by repeated levellings of the soil surface. The drained peatland ecosystem was a strong sink of carbon dioxide in all studied years. Soil CO2 balance was estimated by subtracting the carbon sink of the growing tree stand from NEE, and it showed that also the soil was a sink of carbon. A drought period in one summer significantly decreased the sink through decreased gross primary production. Drought also decreased ecosystem respiration. The site was a small sink for CH4, even when emissions from ditches were taken into account. Despite the continuous carbon sink, peat surface subsided slightly during the 10-year measurement period, which was probably mainly due to compaction of peat. It is concluded that even fifty years after drainage this peatland site acted as a soil C sink due to relatively small changes in water table and in plant community structure compared to similar undrained sites, and the significantly increased tree stand growth and litter production. Although the site is currently a soil C sink, simulation studies with process models are needed to test whether such sites could remain C sinks when managed for forestry over several tree-stand rotations.

scholarly journals Persistent carbon sink at a boreal drained bog forest

2018 ◽  
Vol 15 (11) ◽  
pp. 3603-3624 ◽  
Author(s):  
Kari Minkkinen ◽  
Paavo Ojanen ◽  
Timo Penttilä ◽  
Mika Aurela ◽  
Tuomas Laurila ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Sink ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Process Models ◽  
Litter Production ◽  
Severe Drought ◽  
Tree Stand ◽  
Drought Period ◽  
Soil C

Abstract. Drainage of peatlands is expected to turn these ecosystems into carbon sources to the atmosphere. We measured carbon dynamics of a drained forested peatland in southern Finland over 4 years, including one with severe drought during growing season. Net ecosystem exchange (NEE) of carbon dioxide (CO2) was measured with the eddy covariance method from a mast above the forest. Soil and forest floor CO2 and methane (CH4) fluxes were measured from the strips and from ditches with closed chambers. Biomass and litter production were sampled, and soil subsidence was measured by repeated levellings of the soil surface. The drained peatland ecosystem was a strong sink of carbon dioxide in all studied years. Soil CO2 balance was estimated by subtracting the carbon sink of the growing tree stand from NEE, and it showed that the soil itself was a carbon sink as well. A drought period in one summer significantly decreased the sink through decreased gross primary production. Drought also decreased ecosystem respiration. The site was a small sink for CH4, even when emissions from ditches were taken into account. Despite the continuous carbon sink, peat surface subsided slightly during the 10-year measurement period, which was probably mainly due to compaction of peat. It is concluded that even 50 years after drainage this peatland site acted as a soil C sink due to relatively small changes in the water table and in plant community structure compared to similar undrained sites, and the significantly increased tree stand growth and litter production. Although the site is currently a soil C sink, simulation studies with process models are needed to test whether such sites could remain C sinks when managed for forestry over several tree-stand rotations.

scholarly journals Carbon dioxide fluxes over an ancient broadleaved deciduous woodland in southern England

2010 ◽  
Vol 7 (3) ◽  
pp. 3765-3814 ◽  
Author(s):  
M. V. Thomas ◽  
Y. Malhi ◽  
K. M. Fenn ◽  
J. B. Fisher ◽  
M. D. Morecroft ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Primary Productivity ◽  
Management Practices ◽  
Net Primary Productivity ◽  
Deciduous Forest ◽  
Carbon Sink ◽  
Ecosystem Respiration ◽  
Flux Chamber ◽  
Southern England ◽  
Temperate Deciduous

Abstract. We present results from a study of canopy-atmosphere fluxes of carbon dioxide from 2007 to 2009 above a site in Wytham Woods, an ancient temperate broadleaved deciduous forest in southern England. Gap-filled Net Ecosystem Exchange (NEE) data were partitioned into Gross Primary Productivity (GPP) and ecosystem respiration (Re) and analysed on daily, monthly and annual timescales. Over the continuous 24 month study period annual GPP was estimated at 21.1 Mg C ha−1 yr−1 and Re at 19.8 Mg C ha−1 yr−1; Net Ecosystem Productivity (NEP) was 1.2 Mg C ha−1 yr−1. These estimates are very consistent with independent bottom-up estimates derived from Net Primary Productivity (NPP) and flux chamber measurements in 2008 (GPP=20.3±1.0 Mg C ha−1 yr−1, Re=18.9±1.7 Mg C ha−1 yr−1, biomass increment =~1.4 Mg C ha−1 yr−1). Interannual variability of seasonal NEP was predominantly driven by changes in ecosystem respiration, whereas GPP remained similar for equivalent months in different years. Although solar radiation was the largest influence on daytime CO2 fluxes (R2=0.53 for the summer months), interannual variation in Re appeared to be driven by temperature. Our findings suggest that this ancient woodland site is currently a substantial sink for carbon, resulting from continued growth that is probably a legacy of past management practices abandoned over 40 years ago. Our GPP and Re values are generally higher than other broadleaved temperate deciduous woodlands and may represent the influence of the UK's maritime climate, or the particular species composition of this site. The carbon sink value of Wytham Woods supports the protection and management of temperate deciduous woodlands (including those managed for conservation rather than silvicultural objectives) as a strategy to mitigate atmospheric carbon dioxide increases.

scholarly journals Responses of Forest Carbon Cycle to Drought and Elevated CO2

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 212
Author(s):  
Jun-Lan Xiao ◽  
Feng Zeng ◽  
Qiu-Lan He ◽  
Yu-Xia Yao ◽  
Xiao Han ◽  
...  
Keyword(s):  
Water Stress ◽  
Elevated Co2 ◽  
Carbon Sink ◽  
Ecosystem Respiration ◽  
Co2 Exchange ◽  
Positive Influence ◽  
Research Field ◽  
Co2 Fertilization ◽  
Global Trends ◽  
Elevated Atmospheric Co2

Forests play a pivotal role in mitigating global warming as an important carbon sink. Recent global greening trends reflect a positive influence of elevated atmospheric CO2 on terrestrial carbon uptake. However, increasingly frequent and intense drought events endanger the carbon sequestration function of forests. This review integrates previous studies across scales to identify potential global trends in forest responses to drought and elevated CO2 as well as to identify data needs in this important research field. The inconsistent responses of ecosystem respiration to drought contributes to the change of forest net CO2 exchange, which depends on the balance of opposite effects of warming and water stress on respiration. Whether CO2 fertilization can offset the effects of drought remains controversial, however, we found a potential overestimation of global CO2 fertilization effects because of increasing water stress and other limitations such as light and nutrients (N, P) as well as the possibility of photosynthetic acclimation.

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