Siberian Peatlands a Net Carbon Sink and Global Methane Source Since the Early Holocene

Smith, L. C.; MacDonald, Glen M.; Величко, А.А.; Beilman, David W.; Borisova, Olga; Frey, Karen E.; Kremenetski, K. V.; Sheng, Yongwei

doi:10.1126/science.1090553

Cited by 384 publications

(285 citation statements)

References 23 publications

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“…Some evidence showed that terrestrial ecosystems (e.g., tundra) might be a weak C sink rather than a C source under global climate warming [Shaver et al, 2000;Smith et al, 2004;Zimov et al, 2006b;Hollingsworth et al, 2008;McGuire et al, 2009;Zhuang et al, 2010;Elmendorf et al, 2012;Lu et al, 2012], but other evidence points in the opposite direction [Belshe et al, 2013;Natali et al, 2014]. Our short-term and 50 year long projection showed that annual warming and winter warming increase the C sink strength rather than decrease C. Our study support that the tundra ecosystem will remain as a weak C sink at least in the first half of this century.…”

Section: Resultsmentioning

confidence: 99%

Modeling permafrost thaw and ecosystem carbon cycle under annual and seasonal warming at an Arctic tundra site in Alaska

Luo

Natali

et al. 2014

JGR Biogeosciences

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Permafrost thaw and its impacts on ecosystem carbon (C) dynamics are critical for predicting global climate change. It remains unclear whether annual and seasonal warming (winter or summer) affect permafrost thaw and ecosystem C balance differently. It is also required to compare the short-term stepwise warming and long-term gradual warming effects. This study validated a land surface model, the Community Atmosphere Biosphere Land Exchange model, at an Alaskan tundra site, and then used it to simulate permafrost thaw and ecosystem C flux under annual warming, winter warming, and summer warming. The simulations were conducted under stepwise air warming (2°C yr À1 ) during 2007-2011, and gradual air warming (0.04°C yr À1 ) during 2007-2056. We hypothesized that all warming treatments induced greater permafrost thaw, and larger ecosystem respiration than plant growth thus shifting the ecosystem C sink to C source. Results only partially supported our hypothesis. Climate warming further enhanced C sink under stepwise (6-15%) and gradual (1-8%) warming scenarios as followed by annual warming, winter warming, and summer warming. This is attributed to disproportionally low temperature increase in soil (0.1°C) in comparison to air warming (2°C). In a separate simulation, a greater soil warming (1.5°C under winter warming) led to a net ecosystem C source (i.e., 18 g C m À2 yr À1 ). This suggests that warming tundra can potentially provide positive feedbacks to global climate change. As a key variable, soil temperature and its dynamics, especially during wintertime, need to be carefully studied under global warming using both modeling and experimental approaches.

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Section: Resultsmentioning

confidence: 99%

Modeling permafrost thaw and ecosystem carbon cycle under annual and seasonal warming at an Arctic tundra site in Alaska

Luo

Natali

et al. 2014

JGR Biogeosciences

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“…N concentration; Waldrop and Zak 2006), and excessively high or low pH (e.g., mine spoils). Some of these ecosystems have high enough NPP to result in significant SOM accumulation, such as in peat bogs (Smith et al 2004) and boreal forests . A major concern about climate change is that conditions may become more favorable to microbial activity, possibly leading to destabilization of large quantities of SOM that are currently protected by conditions that suppress biotic activity (Freeman et al 2001) …”

Section: Biotic Suppression and Climatic Stabilizationmentioning

confidence: 99%

Storage and Turnover of Organic Matter in Soil

Torn

Swanston

Castanha

et al. 2009

Biophysico‐Chemical Processes Involving Natural Nonliving Organic Matter in Environmental Systems

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110

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“…The West-Siberian Plain is the largest peatland region of the world, with mires covering over 10,00,000 km 2 (Yefremov and Yefremova 2001;Tanneberger et al 2003;Smith et al 2004). The plain is situated between the Ural Mountains to the west, the Yenisey River to the east and the Altai Mountains to the south.…”

Section: Study Areamentioning

confidence: 99%

Vegetation characteristics and eco-hydrological processes in a pristine mire in the Ob River valley (Western Siberia)

et al. 2007

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Relations between vegetation characteristics and eco-hydrological processes were assessed in a pristine mire in the valley of the Ob River (Western Siberia). Along a transect from the terrace scarp to the river, field data were collected on vegetation composition, peat stratigraphy, peat chemistry, hydrology and hydrochemistry. Based on floristic composition, eight vegetation communities were distinguished. Hydraulic head measurements were used to obtain an indication of groundwater flow directions. The water balance of the mire was calculated with a two-dimensional steady-state numerical groundwater model. Water types were defined based on cluster analysis of hydrochemical data. The results revealed that the dominant hydrological factor in the Ob mire is the discharge of groundwater, which supplies about threefold more water than net precipitation. Although the discharge flux decreases with increasing distance from the terrace scarp, high water levels and a ''groundwater-like'' mire water composition were observed in the major part of the study site. Precipitation and river water play only a minor role. Despite dilution of discharging groundwater with rainwater, spatial differences in pH and solute concentrations of the surficial mire water are small and not reflected in the vegetation composition. Although small amounts of silt and clay were found in the peat in the proximity of the river, indicating the occurrence of river floods in former times, no river-flood zone could be recognized based on hydrochemical characteristics or vegetation composition. A comparison of the Ob mire with well-studied and near-natural mires in the Biebrza River valley (Poland) revealed substantial differences in both vegetation characteristics and the intensity and spatial pattern of eco-hydrological processes. Differences in the 123Plant Ecol (2007) 193:131-145 DOI 10.1007 origin and ratios of water fluxes as well as a dissimilar land use history would seem to be key factors explaining the differences observed.

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Siberian Peatlands a Net Carbon Sink and Global Methane Source Since the Early Holocene

Cited by 384 publications

References 23 publications

Modeling permafrost thaw and ecosystem carbon cycle under annual and seasonal warming at an Arctic tundra site in Alaska

Modeling permafrost thaw and ecosystem carbon cycle under annual and seasonal warming at an Arctic tundra site in Alaska

Storage and Turnover of Organic Matter in Soil

Vegetation characteristics and eco-hydrological processes in a pristine mire in the Ob River valley (Western Siberia)

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