Winter precipitation and snow accumulation drive the methane sink or source strength of Arctic tussock tundra

Blanc‐Betes, E.; Welker, Jeffrey M.; Sturchio, Neil C.; Chanton, Jeffrey P.; Gonzàlez-Meler, Miquel A.

doi:10.1111/gcb.13242

Cited by 53 publications

(56 citation statements)

References 138 publications

(190 reference statements)

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“…Anaerolineae include green non-sulfur bacteria able to thrive in anaerobic environments and have previously been found in similar cold, watersaturated soils (Costello and Schmidt, 2006). These results appear consistent with the increased soil moisture and decreased partial pressure of O 2 documented under increased snowpack at the study site (Blanc-Betes et al, 2016). These shifts in bacterial phyla indicate that, even at the coarsest level of phylogeny and a high degree of variance between samples, deeper snow in winter and associated changes in soil conditions may be driving changes in the belowground community.…”

Section: Bacterial Community Shiftssupporting

confidence: 88%

“…2) shows bacterial community structures to be associated with the snow accumulation treatment as soil chemical properties changed (% C, % N, C : N, and pH), indicating that bacterial beta diversity may respond to indirect changes in soil chemistry in response to winter snow accumulation. The initial effects of increased snowpack result in altered physical factors (greater active layer thaw depth and increased soil temperatures and moisture; Blanc-Betes et al, 2016) which may lead to increased SOM availability and faster enzyme activities with the potential to enhance SOM decomposition. Higher SOM mineralization may promote the documented shifts in aboveground plant communities and increased NPP (Natali et al, 2012;Sturm et al, 2005;Anderson-Smith, 2013), and vege-tation shifts to more shrubby species may alter the chemistry and quality of new litter inputs, ultimately affecting decomposer communities.…”

Section: Bacterial Community Shiftsmentioning

confidence: 99%

“…However, ecosystem C loss may be offset by increased soil moisture, causing hypoxic conditions and limiting R h (Blanc-Betes et al, 2016). Also, microbial mineralization of plant nutrients, such as nitrogen (N) and phosphorus (P), from SOM decomposition are likely to contribute to increased net primary productivity (NPP; Hinzman et al, 2005;Natali et al, 2012;Pattison and Welker, 2014) and cause shifts in vegetation from herbaceous species (cottongrass tussock -Eriophorum vaginatum) towards woody species (Arctic shrubs -Betula nana and Salix pulchra) that may produce a larger amount of plant litter compounds that are more resistant to decomposition (Bret-Harte et al, 2001;Pearson et al, 2013;Sturm et al, 2005;Wahren, 2005).…”

Section: Introductionmentioning

confidence: 99%

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Soil bacterial community and functional shifts in response to altered snowpack in moist acidic tundra of northern Alaska

Ricketts

Poretsky

Welker

et al. 2016

SOIL

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Abstract. Soil microbial communities play a central role in the cycling of carbon (C) in Arctic tundra ecosystems, which contain a large portion of the global C pool. Climate change predictions for Arctic regions include increased temperature and precipitation (i.e. more snow), resulting in increased winter soil insulation, increased soil temperature and moisture, and shifting plant community composition. We utilized an 18-year snow fence study site designed to examine the effects of increased winter precipitation on Arctic tundra soil bacterial communities within the context of expected ecosystem response to climate change. Soil was collected from three preestablished treatment zones representing varying degrees of snow accumulation, where deep snow ∼ 100 % and intermediate snow ∼ 50 % increased snowpack relative to the control, and low snow ∼ 25 % decreased snowpack relative to the control. Soil physical properties (temperature, moisture, active layer thaw depth) were measured, and samples were analysed for C concentration, nitrogen (N) concentration, and pH. Soil microbial community DNA was extracted and the 16S rRNA gene was sequenced to reveal phylogenetic community differences between samples and determine how soil bacterial communities might respond (structurally and functionally) to changes in winter precipitation and soil chemistry. We analysed relative abundance changes of the six most abundant phyla (ranging from 82 to 96 % of total detected phyla per sample) and found four (Acidobacteria, Actinobacteria, Verrucomicrobia, and Chloroflexi) responded to deepened snow. All six phyla correlated with at least one of the soil chemical properties (% C, % N, C : N, pH); however, a single predictor was not identified, suggesting that each bacterial phylum responds differently to soil characteristics. Overall, bacterial community structure (beta diversity) was found to be associated with snow accumulation treatment and all soil chemical properties. Bacterial functional potential was inferred using ancestral state reconstruction to approximate functional gene abundance, revealing a decreased abundance of genes required for soil organic matter (SOM) decomposition in the organic layers of the deep snow accumulation zones. These results suggest that predicted climate change scenarios may result in altered soil bacterial community structure and function, and indicate a reduction in decomposition potential, alleviated temperature limitations on extracellular enzymatic efficiency, or both. The fate of stored C in Arctic soils ultimately depends on the balance between these mechanisms.

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Section: Bacterial Community Shiftssupporting

confidence: 88%

Section: Bacterial Community Shiftsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Soil bacterial community and functional shifts in response to altered snowpack in moist acidic tundra of northern Alaska

Ricketts

Poretsky

Welker

et al. 2016

SOIL

Self Cite

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“…Also, projected changes in vegetation phenology due to climate warming in Arctic tundra might also lead to changes in snow cover e.g. more shrubs will tend to hold more snow during win-110 ter (Blanc-Betes et al, 2016;Domine et al, 2015). A thicker snow layer will insulate the soil column more during autumn and winter, continuing to contribute to preservation of the heat of the active layer after the preceding growing (zero curtain period) season.…”

Section: Introductionmentioning

confidence: 99%

“…In other Arctic permafrost tundra ecosystems, however, winter CH 4 emissions were one to two orders of magnitude lower than the emissions during summer, and only accumulate in the snowpack in the presence of layers of ice blocking their exit route to the atmosphere (Pirk et al, 2016). Wickland et al (1999) ter (Blanc-Betes et al, 2016;Domine et al, 2015). A thicker snow layer will insulate the soil column more during autumn and winter, continuing to contribute to preservation of the heat of the active layer after the preceding growing (zero curtain period) season.…”

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confidence: 99%

Year-round simulated methane emissions from a permafrost ecosystem in Northeast Siberia

Castro-Morales¹,

Kleinen²,

Kaiser³

et al. 2017

Preprint

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15Methane emissions to the atmosphere from natural wetlands are estimated to be about 25 % of the total global CH 4 emissions. In the Arctic, these areas are highly vulnerable to the effects of global warming due to atmospheric warming amplification, leading to soil hydrologic changes involving permafrost thaw, formation of deeper active layers, and rising topsoil temperatures. As a result, projected increase in the degradation of permafrost carbon will likely 20 lead to higher CO 2 and CH 4 emissions from these areas. Here we evaluate year-round modelsimulated CH 4 emissions to the atmosphere (for 2014 and 2015) from a region of northeastern Siberia in the Russian Far East. Four CH 4 transport pathways are modeled with a revisited version of the process-based JSBACH-methane model: plant-mediated transport, ebullition and molecular diffusion in the presence or absence of snow. This model also simulates 25 the extent of wetlands as the fraction of inundated area in a model grid cell using a TOP-MODEL approach, and these are evaluated against a highly resolved wetland product from remote sensing data. The model CH 4 emissions are compared against ground-based CH 4 flux measurements using the eddy covariance technique and flux chambers in the same area of study. The magnitude of the summertime modeled CH 4 emissions is comparable to those 30 from eddy covariance and flux chamber measurements. However, wintertime modeled CH 4 emissions are underestimated by one order of magnitude. The annual CH 4 emissions are dominated by plant-mediated transport (61 %), followed by ebullition (~35 %). Molecular diffusion of CH 4 from the soil into the atmosphere during summer is negligible (0.02 %) compared to the diffusion through the snow during the non-growing season (~4 %). vestigate the relationship between temporal changes in the CH 4 fluxes, soil temperature, and soil moisture content. Our results highlight the heterogeneity in CH 4 emissions at a landscape scale and suggest that further improvements to the representation of large-scale hydrological Biogeosciences Discuss., https://doi.org/10.5194/bg-2017-310 Manuscript under review for journal Biogeosciences Discussion started: 24 July 2017 c Author(s) 2017. CC BY 4.0 License.2 conditions in the model, especially at regional scales in Arctic ecosystems influenced by permafrost thaw, will allow us to arrive at a more process-oriented land surface scheme and 40 better simulate CH 4 emissions under climate change.Keywords: methane, permafrost, carbon cycle, Arctic, wetlands, winter emissions IntroductionDuring the last 30 years, atmospheric temperatures at northern high-latitudes have risen more 45 than the global average (Schuur et al., 2015; Serreze et al., 2000). In consequence, many permafrost areas in these regions have experienced expedited thawing rates in recent years.Permafrost in northern high-latitude ecosystems contains twice as much carbon as the current carbon pool in the atmosphere and about half of global soil organic carbon (Hugelius et al., 2...

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Greenhouse gas balance over thaw‐freeze cycles in discontinuous zone permafrost

et al. 2017

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Peat in the discontinuous permafrost zone contains a globally significant reservoir of carbon that has undergone multiple permafrost‐thaw cycles since the end of the mid‐Holocene (~3700 years before present). Periods of thaw increase C decomposition rates which leads to the release of CO2 and CH4 to the atmosphere creating potential climate feedback. To determine the magnitude and direction of such feedback, we measured CO2 and CH4 emissions and modeled C accumulation rates and radiative fluxes from measurements of two radioactive tracers with differing lifetimes to describe the C balance of the peatland over multiple permafrost‐thaw cycles since the initiation of permafrost at the site. At thaw features, the balance between increased primary production and higher CH4 emission stimulated by warmer temperatures and wetter conditions favors C sequestration and enhanced peat accumulation. Flux measurements suggest that frozen plateaus may intermittently (order of years to decades) act as CO2 sources depending on temperature and net ecosystem respiration rates, but modeling results suggest that—despite brief periods of net C loss to the atmosphere at the initiation of thaw—integrated over millennia, these sites have acted as net C sinks via peat accumulation. In greenhouse gas terms, the transition from frozen permafrost to thawed wetland is accompanied by increasing CO2 uptake that is partially offset by increasing CH4 emissions. In the short‐term (decadal time scale) the net effect of this transition is likely enhanced warming via increased radiative C emissions, while in the long‐term (centuries) net C deposition provides a negative feedback to climate warming.

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Winter precipitation and snow accumulation drive the methane sink or source strength of Arctic tussock tundra

Cited by 53 publications

References 138 publications

Soil bacterial community and functional shifts in response to altered snowpack in moist acidic tundra of northern Alaska

Soil bacterial community and functional shifts in response to altered snowpack in moist acidic tundra of northern Alaska

Year-round simulated methane emissions from a permafrost ecosystem in Northeast Siberia

Greenhouse gas balance over thaw‐freeze cycles in discontinuous zone permafrost

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