Temperature, moisture and freeze–thaw controls on CO2 production in soil incubations from northern peatlands

Byun, Eunji; Rezanezhad, Fereidoun; Fairbairn, Linden; Slowinski, Stephanie; Basiliko, Nathan; Price, Jonathan S.; Quinton, William L.; Roy-Léveillée, Pascale; Webster, Kara; Cappellen, Philippe Van

doi:10.1038/s41598-021-02606-3

Cited by 26 publications

(18 citation statements)

References 86 publications

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“…Therefore, we here defined the macroporosity as pores having a diameter of greater than 30 μm. The relation between macroporosity and log 10 K s is supported by a recent study from Wang M. et al (2021), who observed a moderate correlation between macroporosity and log 10 K s for various kinds of peat types (Pearson's correlation coefficient > 0.55). We here found that the function between macroporosity and log 10 K s is not affected by the FTCs (Figure 4), indicating that the macroporosity is the main factor controlling the K s of peat at a centimeter scale.…”

Section: Frontiers In Environmental Sciencesupporting

confidence: 64%

Freeze-thaw cycles alter soil hydro-physical properties and dissolved organic carbon release from peat

Liu

Rezanezhad²,

Žák³

et al. 2022

Front. Environ. Sci.

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The ongoing climate warming is likely to increase the frequency of freeze-thaw cycles (FTCs) in cold-temperate peatland regions. Despite the importance of soil hydro-physical properties in water and carbon cycling in peatlands, the impacts of FTCs on peat properties as well as carbon sequestration and release remain poorly understood. In this study, we collected undisturbed topsoil samples from two drained lowland fen peatlands to investigate the impact of FTCs on hydro-physical properties as well as dissolved organic carbon (DOC) fluxes from peat. The soil samples were subject to five freeze-thaw treatments, including a zero, one, three, five, ten cycles (FTC0, FTC1, FTC3, FTC5, and FTC10, respectively). Each FTC was composed of 24 h of freezing (−5°C) and 24 h of thawing (5°C) and the soil moisture content during the freeze-thaw experiment was adjusted to field capacity. The results showed that the FTCs substantially altered the saturated hydraulic conductivity (Ks) of peat. For peat samples with low initial Ks values (e.g., < 0.2 × 10−5 m s−1), Ks increased after FTCs. In contrast, the Ks of peat decreased after freeze-thaw, if the initial Ks was comparably high (e.g., > 0.8 × 10−5 m s−1). Overall, the average Ks values of peatlands decreased after FTCs. The reduction in Ks values can be explained by the changes in macroporosity. The DOC experiment results revealed that the FTCs could increase DOC concentrations in leachate, but the DOC fluxes decreased mainly because of a reduction in water flow rate as well as Ks. In conclusion, soil hydraulic properties of peat (e.g., Ks) are affected by freezing and thawing. The dynamics of soil hydraulic properties need to be explicitly addressed in the quantification and modelling of the water flux and DOC release from peatlands.

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Section: Frontiers In Environmental Sciencesupporting

confidence: 64%

Freeze-thaw cycles alter soil hydro-physical properties and dissolved organic carbon release from peat

Liu

Rezanezhad²,

Žák³

et al. 2022

Front. Environ. Sci.

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“…We found that soil freezing, and thawing combined with changes in air and soil temperature caused a high degree of variability in CO 2 fluxes in all treatments. This indicated that soil warming regulated and enhanced microbial respiration during the spring freeze-thaw (Byun et al, 2021;King et al, 2021;Rafat et al, 2021). We found that CO 2 fluxes were different among freeze-thaw phases where the dry phase had highest flux compared to the wet and waterlogged phases.…”

Section: Freeze Thaw Phases and Temperature Influence On Greenhouse G...mentioning

confidence: 71%

“…In addition, the intensity of soil respiration during freeze-thaw is positively dependent on soil temperature and moisture (Schipper et al, 2014;Byun et al, 2021). Since no crops or plants were present over the winter, the CO 2 flux quantified in our study was a direct measurement of soil microbial activity (Hung et al, 2021).…”

Section: Freeze Thaw Phases and Temperature Influence On Greenhouse G...mentioning

confidence: 99%

Spring Freeze–Thaw Stimulates Greenhouse Gas Emissions From Agricultural Soil

Badewa

Yeung²,

Rezanezhad³

et al. 2022

Front. Environ. Sci.

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In temperate cold regions, the gradual resurgence of soil microbial activity during spring freeze-thaw events is frequently associated with greenhouse gas emissions. Enhanced greenhouse gas fluxes during spring freeze-thaw are related to the mineralization of bioavailable substrates, which may be elevated when soil is amended with organic residues (e.g., biobased residues such as compost, digestate, biosolids). The objective of this study was to determine the impact of biobased residues, compared to urea fertilizer, on greenhouse gas emissions during spring freeze-thaw events. The field treatments included urea (170 kg N ha−1 y−1), composted food waste (240 kg N ha−1 y−1), hydrolyzed biosolids (215 kg N ha−1 y−1), and anaerobic digestate (231 kg N ha−1 y−1). Headspace gases were sampled from a closed static chamber in each replicate plot (n = 4) and categorized with three transient spring freeze-thaw phases (waterlogged, wet, and dry). Among the treatments, nitrous oxide (N2O) flux was significantly different (p < 0.05) where compost had the highest emission and digestate lowest while carbon dioxide (CO2) and methane (CH4) fluxes were not significantly different (p > 0.05). The greenhouse gas fluxes were significantly different among the freeze-thaw events (p < 0.05) likely due to intense microbial activity and anaerobic conditions. The CO2 and CH4 emissions were related to N2O emission (p < 0.05), and soil temperature strongly correlated with CO2 fluxes. This suggested that soil warming driven by ambient conditions as well as the type and quantity of carbon input influenced soil microbial activity, leading to greenhouse gases production. Therefore, soil amended with biobased residues may either increase or reduce greenhouse gas fluxes during spring freeze-thaw events depending on the source and production method of the organic material.

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“…This has repercussions for net ecosystem-scale carbon fluxes considering the uncertainties in carbon offsets from growing season primary productivity [1][2][3][4]. A growing body of literature has emerged alluding to substantial increases in soil carbon dioxide (CO 2 ) and methane (CH 4 ) emissions during the NGS [5][6][7][8][9][10][11][12][13][14][15][16][17]. Despite these findings, there is a lack of consistency in how the NGS is defined, with the start and end dates of the NGS in a calendar year assigned differently among studies [18].…”

Section: Introductionmentioning

confidence: 99%

“…In addition, our new compilation over more years of data (1998-2010) shows wide ranges of daily NEE rates during October and April, that is, near the beginning and end of the NGS (figure 1). This variability in daily NEE is at least in part due to interannual shifts in the start and end of the NGS [17]. As leafing events or greenness changes are not easy to monitor in the usually evergreen dominated or open vegetation of northern peatlands, climatic variables may be of more practical use to identify the ecological season transitions and reversals of the NEE direction (i.e., net heterotrophy or net autotrophy) [20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

The definition of the non-growing season matters: a case study of net ecosystem carbon exchange from a Canadian peatland

Rafat¹,

Byun²,

Rezanezhad³

et al. 2022

Environ. Res. Commun.

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Climate change is a threat to the 500 Gt carbon stored in northern peatlands. As the region warms, the rise in mean temperature is more pronounced during the non-growing season (NGS, i.e., winter and parts of the shoulder seasons) when net ecosystem loss of carbon dioxide (CO2) occurs. Many studies have investigated the impacts of climate warming on NGS CO2 emissions, yet there is a lack of consistency amongst researchers in how the NGS period is defined. This complicates the interpretation of NGS CO2 emissions and hinders our understanding of seasonal drivers of key carbon exchange processes. Here, we analyze the impact of alternative definitions of the NGS for a peatland site with multiple years of CO2 flux records. Three climatic parameters were considered to define the NGS: air temperature, soil temperature, and snow cover. Our findings reveal positive correlations between estimates of the cumulative non-growing season net ecosystem CO2 exchange (NGS-NEE) and the length of the NGS for each alternative definition, with the greatest proportion of variability explained using snow cover (R 2 = 0.89, p < 0.001), followed by air temperature (R 2 = 0.79, p < 0.001) and soil temperature (R 2 = 0.54, p = 0.006). Using these correlations, we estimate average daily NGS CO2 emitted between 1.42 and 1.90 gCO2 m-2, depending on which NGS definition is used. Our results highlight the need to explicitly define the NGS based on available climatic parameters to account for regional climate and ecosystem variability.

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Temperature, moisture and freeze–thaw controls on CO2 production in soil incubations from northern peatlands

Cited by 26 publications

References 86 publications

Freeze-thaw cycles alter soil hydro-physical properties and dissolved organic carbon release from peat

Freeze-thaw cycles alter soil hydro-physical properties and dissolved organic carbon release from peat

Spring Freeze–Thaw Stimulates Greenhouse Gas Emissions From Agricultural Soil

The definition of the non-growing season matters: a case study of net ecosystem carbon exchange from a Canadian peatland

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