Trace gas exchange in a high‐Arctic valley: 1. Variationsin CO<sub>2</sub> and CH<sub>4</sub> Flux between tundra vegetation types

Christensen, Torben R.; Friborg, Thomas; Sommerkorn, Martin; Kaplan, Jed O.; Illeris, Lotte; Soegaard, H.; Nordstroem, Claus; Jonasson, Sven

doi:10.1029/1999gb001134

Cited by 153 publications

(193 citation statements)

References 44 publications

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“…Integrated summer season emissions, roughly 4.5 g CH 4 m -2 for the season, also match well with previous estimates for the same climatic and ecosystem setting 6,7 .…”

Section: Letterssupporting

confidence: 85%

“…The observed growing season emission dynamics are comparable to earlier work at the same 6,7 and at similar tundra sites 12 . Integrated summer season emissions, roughly 4.5 g CH 4 m -2 for the season, also match well with previous estimates for the same climatic and ecosystem setting 6,7 .…”

Section: Letterssupporting

confidence: 85%

“…Methane emissions from permafrost dominated tundra regions are well documented [5][6][7] and also recognized as considerable contributors to the dynamics of high-latitude atmospheric methane concentrations 8,9 . The scale and dynamics of growing-season methane emissions from tundra settings have been documented mostly through flux measurements made with low time resolution using manual chambers 5,6,10 together with some at higher time resolution taken only during the growing season 7,11,12 .…”

Section: Lettersmentioning

confidence: 99%

“…The scale and dynamics of growing-season methane emissions from tundra settings have been documented mostly through flux measurements made with low time resolution using manual chambers 5,6,10 together with some at higher time resolution taken only during the growing season 7,11,12 . Here we report a data set that extends hourly CH 4 flux measurements from a high Arctic setting into the frozen season.…”

Section: Lettersmentioning

confidence: 99%

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Large tundra methane burst during onset of freezing

Mastepanov

Sigsgaard

Dlugokencky

et al. 2008

Nature

304

279

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“…Integrated summer season emissions, roughly 4.5 g CH 4 m -2 for the season, also match well with previous estimates for the same climatic and ecosystem setting 6,7 .…”

Section: Letterssupporting

confidence: 85%

Section: Letterssupporting

confidence: 85%

Section: Lettersmentioning

confidence: 99%

Section: Lettersmentioning

confidence: 99%

See 2 more Smart Citations

Large tundra methane burst during onset of freezing

Mastepanov

Sigsgaard

Dlugokencky

et al. 2008

Nature

304

279

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“…For example, long-term warming of soil and vegetation in a subalpine meadow produced changes in litter input to the soil due to a shift in community composition from forbs (which produce labile litter) to shrubs (which produce more recalcitrant litter) (19). Also, community-level effects of herbivory are a potentially important component of biospheric feedbacks to climate in the Arctic because colonization by deciduous shrubs would allow greater biomass accumulation than that which is possible in a graminoid-dominated community (34), with important consequences for soil C and nitrogen (N) storage and gas exchange (40,41).…”

Section: Discussionmentioning

confidence: 99%

Opposing plant community responses to warming with and without herbivores

Post

Pedersen

2008

Proc. Natl. Acad. Sci. U.S.A.

430

495

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If controls over primary productivity and plant community composition are mainly environmental, as opposed to biological, then global change may result in large-scale alterations in ecosystem structure and function. This view appears to be favored among investigations of plant biomass and community responses to experimental and observed warming. In far northern and arctic ecosystems, such studies predict increasing dominance of woody shrubs with future warming and emphasize the carbon (C)-sequestration potential and consequent atmospheric feedback potential of such responses. In contrast to previous studies, we incorporated natural herbivory by muskoxen and caribou into a 5-year experimental investigation of arctic plant community response to warming. In accordance with other studies, warming increased total community biomass by promoting growth of deciduous shrubs (dwarf birch and gray willow). However, muskoxen and caribou reduced total community biomass response, and responses of birch and willow, to warming by 19%, 46%, and 11%, respectively. Furthermore, under warming alone, the plant community shifted after 5 years away from graminoid-dominated toward dwarf birch-dominated. In contrast, where herbivores grazed, plant community composition on warmed plots did not differ from that on ambient plots after 5 years. These results highlight the potentially important and overlooked influences of vertebrate herbivores on plant community response to warming and emphasize that conservation and management of large herbivores may be an important component of mitigating ecosystem response to climate change.arctic ͉ climate change ͉ global warming ͉ herbivory ͉ species interactions

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Effects of simulated spring thaw of permafrost from mineral cryosol on CO₂ emissions and atmospheric CH₄ uptake

et al. 2015

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Previous studies investigating organic-rich tundra have reported that increasing biodegradation of Arctic tundra soil organic carbon (SOC) under warming climate regimes will cause increasing CO 2 and CH 4 emissions. Organic-poor, mineral cryosols, which comprise 87% of Arctic tundra, are not as well characterized. This study examined biogeochemical processes of 1 m long intact mineral cryosol cores (1-6% SOC) collected in the Canadian high Arctic. Vertical profiles of gaseous and aqueous chemistry and microbial composition were related to surface CO 2 and CH 4 fluxes during a simulated spring/summer thaw under light versus dark and in situ versus water saturated treatments. CO 2 fluxes attained 0.8 ± 0.4 mmol CO 2 m À2 h À1 for in situ treatments, of which 85 ± 11% was produced by aerobic SOC oxidation, consistent with field observations and metagenomic analyses indicating aerobic heterotrophs were the dominant phylotypes. The Q 10 values of CO 2 emissions ranged from 2 to 4 over the course of thawing. CH 4 degassing occurred during initial thaw; however, all cores were CH 4 sinks at atmospheric concentration CH 4 . Atmospheric CH 4 uptake rates ranged from À126 ± 77 to À207 ± 7 nmol CH 4 m À2 h À1 with CH 4 consumed between 0 and 35 cm depth.Metagenomic and gas chemistry analyses revealed that high-affinity Type II methanotrophic sequence abundance and activity were highest between 0 and 35 cm depth. Microbial sulfate reduction dominated the anaerobic processes, outcompeting methanogenesis for H 2 and acetate. Fluxes, microbial community composition, and biogeochemical rates indicate that mineral cryosols of Axel Heiberg Island act as net CO 2 sources and atmospheric CH 4 sinks during summertime thaw under both in situ and water saturated states.

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Trace gas exchange in a high‐Arctic valley: 1. Variationsin CO₂ and CH₄ Flux between tundra vegetation types

Cited by 153 publications

References 44 publications

Large tundra methane burst during onset of freezing

Large tundra methane burst during onset of freezing

Opposing plant community responses to warming with and without herbivores

Effects of simulated spring thaw of permafrost from mineral cryosol on CO₂ emissions and atmospheric CH₄ uptake

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Trace gas exchange in a high‐Arctic valley: 1. Variationsin CO2 and CH4 Flux between tundra vegetation types

Cited by 153 publications

References 44 publications

Large tundra methane burst during onset of freezing

Large tundra methane burst during onset of freezing

Opposing plant community responses to warming with and without herbivores

Effects of simulated spring thaw of permafrost from mineral cryosol on CO2 emissions and atmospheric CH4 uptake

Contact Info

Product

Resources

About

Trace gas exchange in a high‐Arctic valley: 1. Variationsin CO₂ and CH₄ Flux between tundra vegetation types

Effects of simulated spring thaw of permafrost from mineral cryosol on CO₂ emissions and atmospheric CH₄ uptake