Heterogeneity of carbon loss and its temperature sensitivity in East-European subarctic tundra soils

Diáková, Kateřina; Čapek, Petr; Kohoutová, Iva; Mpamah, Promise; Bárta, Jiří; Biasi, Christina; Martikainen, Pertti J.; Šantrůčková, Hana

doi:10.1093/femsec/fiw140

Cited by 11 publications

(12 citation statements)

References 85 publications

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“…Second, the cumulative CO 2 fluxes in the wet mesocosms were partly determined by short‐term emission peaks, associated with a temporarily lowered water table during the thawing process (Figure S3a) and associated changes in peat redox chemistry caused by these water table fluctuations. These emission peaks show a reoxygenation of electron acceptors (Knorr & Blodau, ), but also indicate the presence of a labile C pool and active microbial community, well adapted to anaerobic conditions, as has been shown earlier for old peat soils (Diáková et al, ). Hence, the timing and magnitude of CO 2 emissions from wet mesocosms was governed by the position of the water table which, when lowered, enabled rapid out‐diffusion of CO 2 .…”

Section: Discussionsupporting

confidence: 53%

Ecosystem carbon response of an Arctic peatland to simulated permafrost thaw

Voigt

Marushchak

Mastepanov

et al. 2019

Global Change Biology

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Permafrost peatlands are biogeochemical hot spots in the Arctic as they store vast amounts of carbon. Permafrost thaw could release part of these long‐term immobile carbon stocks as the greenhouse gases (GHGs) carbon dioxide (CO2) and methane (CH4) to the atmosphere, but how much, at which time‐span and as which gaseous carbon species is still highly uncertain. Here we assess the effect of permafrost thaw on GHG dynamics under different moisture and vegetation scenarios in a permafrost peatland. A novel experimental approach using intact plant–soil systems (mesocosms) allowed us to simulate permafrost thaw under near‐natural conditions. We monitored GHG flux dynamics via high‐resolution flow‐through gas measurements, combined with detailed monitoring of soil GHG concentration dynamics, yielding insights into GHG production and consumption potential of individual soil layers. Thawing the upper 10–15 cm of permafrost under dry conditions increased CO2 emissions to the atmosphere (without vegetation: 0.74 ± 0.49 vs. 0.84 ± 0.60 g CO2–C m−2 day−1; with vegetation: 1.20 ± 0.50 vs. 1.32 ± 0.60 g CO2–C m−2 day−1, mean ± SD, pre‐ and post‐thaw, respectively). Radiocarbon dating (14C) of respired CO2, supported by an independent curve‐fitting approach, showed a clear contribution (9%–27%) of old carbon to this enhanced post‐thaw CO2 flux. Elevated concentrations of CO2, CH4, and dissolved organic carbon at depth indicated not just pulse emissions during the thawing process, but sustained decomposition and GHG production from thawed permafrost. Oxidation of CH4 in the peat column, however, prevented CH4 release to the atmosphere. Importantly, we show here that, under dry conditions, peatlands strengthen the permafrost–carbon feedback by adding to the atmospheric CO2 burden post‐thaw. However, as long as the water table remains low, our results reveal a strong CH4 sink capacity in these types of Arctic ecosystems pre‐ and post‐thaw, with the potential to compensate part of the permafrost CO2 losses over longer timescales.

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Section: Discussionsupporting

confidence: 53%

Ecosystem carbon response of an Arctic peatland to simulated permafrost thaw

Voigt

Marushchak

Mastepanov

et al. 2019

Global Change Biology

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“…Thus, in terms of C pool parameters, the potential C release from the northern permafrost region will depend not only on SOC quantity but also on soil organic matter (SOM) lability (i.e., the rate at which soil organic matter will decay following warming and thawing). Laboratory incubation experiments that consider both different types of substrates (e.g., Schädel et al, 2014) and time of incubation (e.g., Elberling et al, 2013) are an important tool to assess potential C release from permafrost soils and deposits.…”

Section: Introductionmentioning

confidence: 99%

Lability classification of soil organic matter in the northern permafrost region

et al. 2020

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Abstract. The large stocks of soil organic carbon (SOC) in soils and deposits of the northern permafrost region are sensitive to global warming and permafrost thawing. The potential release of this carbon (C) as greenhouse gases to the atmosphere does not only depend on the total quantity of soil organic matter (SOM) affected by warming and thawing, but it also depends on its lability (i.e., the rate at which it will decay). In this study we develop a simple and robust classification scheme of SOM lability for the main types of soils and deposits in the northern permafrost region. The classification is based on widely available soil geochemical parameters and landscape unit classes, which makes it useful for upscaling to the entire northern permafrost region. We have analyzed the relationship between C content and C-CO2 production rates of soil samples in two different types of laboratory incubation experiments. In one experiment, ca. 240 soil samples from four study areas were incubated using the same protocol (at 5 ∘C, aerobically) over a period of 1 year. Here we present C release rates measured on day 343 of incubation. These long-term results are compared to those obtained from short-term incubations of ca. 1000 samples (at 12 ∘C, aerobically) from an additional three study areas. In these experiments, C-CO2 production rates were measured over the first 4 d of incubation. We have focused our analyses on the relationship between C-CO2 production per gram dry weight per day (µgC-CO2 gdw−1 d−1) and C content (%C of dry weight) in the samples, but we show that relationships are consistent when using C ∕ N ratios or different production units such as µgC per gram soil C per day (µgC-CO2 gC−1 d−1) or per cm3 of soil per day (µgC-CO2 cm−3 d−1). C content of the samples is positively correlated to C-CO2 production rates but explains less than 50 % of the observed variability when the full datasets are considered. A partitioning of the data into landscape units greatly reduces variance and provides consistent results between incubation experiments. These results indicate that relative SOM lability decreases in the order of Late Holocene eolian deposits to alluvial deposits and mineral soils (including peaty wetlands) to Pleistocene yedoma deposits to C-enriched pockets in cryoturbated soils to peat deposits. Thus, three of the most important SOC storage classes in the northern permafrost region (yedoma, cryoturbated soils and peatlands) show low relative SOM lability. Previous research has suggested that SOM in these pools is relatively undecomposed, and the reasons for the observed low rates of decomposition in our experiments need urgent attention if we want to better constrain the magnitude of the thawing permafrost carbon feedback on global warming.

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“…Diakova et al (2016) also observed that certain microbial groups are capable of adjusting to the absence of oxygen and thriving under anaerobic conditions. Therefore, The soil carbon (C) and nitrogen (N) contents are measured by an elemental analyzer (vario Macro cube, Elementar, Germany).…”

Section: Aeration Statusmentioning

confidence: 95%

“…Q 10 evaluation is usually based on instantaneous CO 2 flux rates (Chang et al, 2012;Fang and Moncrieff, 2001;Karhu et al, 2014;Sun et al, 2016;Waldrop et al, 2010), time spans needed for an identical amount of C mineralization (Bracho et al, 2016;Wang et al, 2013;Zhu and Cheng, 2011), cumulative C flux over a given time period (Conant et al, 2008;Hamdi et al, 2013;Podrebarac et al, 2016), or microbial activity as a function of temperature (Diakova et al, 2016;Karhu et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…Thus, the kinetic parameters of various soil C pools should be fitted to the observational data to determine the temperature sensitivity of the C mineralization, including the rate constants and the relative sizes of the C pools of varying decomposability (Davidson and Janssens, 2006). Furthermore, the temperature sensitivity of C mineralization not only varies in those kinetic properties, which are partially determined by soil properties , but also changes with environmental conditions, such as constant vs. varying temperature regimes (Conant et al, 2008;Fang et al, 2005;Nakajima et al, 2016;Xia et al, 2009;Zhu and Cheng, 2011), the aeration statuses (Blagodatskaya et al, 2014;Devêvre and Horwáth, 2000;Diakova et al, 2016), the forest stands (Guo et al, 2016;Gutiérrez-Girón et al, 2015;Rey and Jarvis, 2006), and the soil horizons (Laganière et al, 2015;Xu et al, 2014). These constraints, especially the temperature and the aeration status, are fixed as constant in most studies, and a continuously changing vs. constant environmental comparison has rarely been scrutinized (Conant et al, 2008;Hartley et al, 2008;Pettersson and Bååth, 2003;Ranneklev and Bååth, 2001).…”

Section: Introductionmentioning

confidence: 99%

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Q10 values vary with different kinetic properties of C mineralization

Bai

Lin

et al. 2017

Pedobiologia

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A B S T R A C TTemperature response quotient (Q 10 ) is a critical parameter for evaluating global additional carbon (C) release with climate change. However, its value is usually derived from time span or instantaneous rate or cumulative amount of C flux, giving a very one-sided account of thermal sensitivity of C cycling. Through a 117-day laboratory incubation study, we estimated Q 10 values simultaneously with the labile (a 0 ) and recalcitrant C proportions and their rate constants, and then tested for any variances of these kinetic properties in different vegetation stands, soil horizons, aeration statuses, and thermal settings (i.e., diurnally-varying, constant low and constant high temperatures). A regularly varying temperature regime increased the exploitation of labile C resources (i.e., high a 0 ) and required longer time spans (i.e., low rate constants). The constant high temperature induced the exhaustive depletion of the labile C pool and motivated a very rapid and short-term C mineralization process. The constant low temperature treatment was characterized by the lowest a 0 but by medium rate constants because low temperature slowed the C mineralization processes but retained high level of the original C processing diversity. Therefore, a 0 and the rate constants showed discrepancies in their temperature sensitivities as revealed by pairwise comparisons of temperature regimes. Such discrepancies were also supported by pairwise comparisons of aeration statuses, forest stands and soil horizons. The Q 10 bias between C mineralization a 0 and rate constants in this laboratory experiment is attributed to the inherently distinct properties of these two parameters, as a 0 and its Q 10 are closely correlated with the sizes of the easily available C pool, while rate constants and their Q 10 variances explain the temporal scale of the same C mineralization process. Our findings suggest a combined application of a 0 and rate constants for exploring the temperature sensitivity of C mineralization in future studies.

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Heterogeneity of carbon loss and its temperature sensitivity in East-European subarctic tundra soils

Cited by 11 publications

References 85 publications

Ecosystem carbon response of an Arctic peatland to simulated permafrost thaw

Ecosystem carbon response of an Arctic peatland to simulated permafrost thaw

Lability classification of soil organic matter in the northern permafrost region

Q10 values vary with different kinetic properties of C mineralization

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