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Climate warming in high latitudes impacts CO2 sequestration of the northern peatlands through the changes in production and decomposition processes. The response of the net CO2 fluxes between ecosystems and the atmosphere to climate change and weather anomalies can vary across forest and non-forest peatlands. To better understand the differences in CO2 dynamics at forest and non-forest boreal peatlands induced by changes in environmental conditions, the estimates of interannual variability in the net ecosystem exchange (NEE), total ecosystem respiration (TER), and gross primary production (GPP) was obtained at two widespread peatland ecosystems – paludified spruce forest and the adjacent ombrotrophic bog in the southern taiga of west Russia using 6 years of paired eddy covariance flux measurements. Both positive and negative annual and growing season air temperature and precipitation anomalies were observed in the period of measurement (2015–2020). Flux measurements showed that, in spite of the lower growing season TER (332±17 ... 339±15 gC m -2) and GPP (442±13 ... 464± 11 gC m -2) rates, the bog had a higher CO2 uptake rates (NEE was -132±11 ... -108±6) than the forest, except for the warmest and the wettest year of the period (2020), and was an atmospheric CO2 sink in the selected years, while the forest was a CO2 sink or source, depending on the environmental conditions. Growing season NEE at the forest site was between -142±48 and 28±40 gC m -2 , TER between 1135±64 and 1366±58 gC m -2 , and GPP between 1207±66 and 1462±107 gC m -2. Annual NEE at the forest was between -62±49 and 145±41 gC m -2 , TER between 1429±87 and 1652±44 C m -2 , and GPP between 1345±89 and 1566±41 gC m -2 , respectively. Under the anomalously warm winter conditions with sparse and thin snow cover (2019/2020), the increased daily GPP, TER, and net CO2 uptake at the forest was observed, while at the bog, the changes in CO2 fluxes between the warm and cold winters were not significant. This study suggests that the warming in winter can increase the CO2 uptake of the paludified spruce forests of the southern taiga in non-growing seasons. [ABSTRACT FROM AUTHOR]

Climate extremes and anomalies modify the CO2 ecosystem–atmosphere exchange of the boreal forests and consequently alter the terrestrial carbon stocks and the atmospheric greenhouse gas concentrations. The effects of the anomalous weather conditions on the CO2 net ecosystem exchange (NEE), total ecosystem respiration (TER), and gross primary production (GPP) of the typical southern taiga nemorose spruce forest were analyzed using continuous eddy covariance flux measurements in the 2015–2020 period. The forest was found to be a source of atmospheric CO2 in 2016, 2017, 2019, and 2020 (the mean annual GPP/TER ratio was between 0.87 and 0.97). In 2018, the forest was found to act as a CO2 sink (GPP/TER = 1.47) when a positive temperature anomaly in the growing season was accompanied by a negative precipitation anomaly and increased global radiation. The early start of the CO2 uptake in the anomalously warm winter of 2019/2020 did not result in an increase in the annual GPP/TER ratio (0.90). The comparison of the flux data obtained from the nemorose spruce forest on the well-drained soils with the data obtained from paludified spruce forest in the same landscape showed that the mean annual GPP/TER ratio of the sites alternatively responded to the mentioned anomalies. This study suggests that a variety of soil moisture regimes across the southern taiga spruce forests provide a non-uniformity in the response reactions of the CO2 ecosystem–atmosphere exchange on the climate anomalies. [ABSTRACT FROM AUTHOR]

Climate warming in high latitudes impacts CO2 sequestration of northern peatlands through the changes in both production and decomposition processes. The response of the net CO2 fluxes between ecosystems and the atmosphere to the climate change and weather anomalies can vary across the forest and non-forest peatlands. To better understand the differences in CO2 dynamics at forest and non-forest boreal peatlands induced by changes in environmental conditions the estimates of interannual variability of the net ecosystem exchange (NEE), total ecosystem respiration (TER) and gross primary production (GPP) was obtained at two widespread peatland ecosystems - paludified spruce forest and adjacent ombrotrophic bog in the southern taiga of west Russia using 6-year of paired eddy covariance flux measurements. The period of measurements (2015-2020) was characterized by both positive and negative annual and growing season air temperature and precipitation anomalies. Flux measurements showed that in spite of the lower growing season TER (332…339 gC x m-2) and GPP (442…464 gC x m-2) rates the bog had a lower NEE (-132…-108) than the forest excepting the warmest and the wettest year of the period and was a sink of atmospheric CO2 in the selected years while the forest was a CO2 sink or source between years depending on the environmental conditions. Growing season NEE at the forest site was between -142 and 28 gC x m-2, TER between 1135 and 1366 gC x m-2 and GPP between 1207 and 1462 gC x m-2. Annual NEE at the forest was between -62 and 145 gC x m-2, TER between 1429 and 1652 gC x m-2 and GPP between 1345 and 1566 gC x m-2 respectively. Anomalously warm winter with sparse and thin snow cover lead to the increased GPP as well as lower NEE in early spring at forest and to the increased spring TER at the bog. Also, the shifting of the compensation point to the earlier dates at the forest and to the later dates at the bog following the warmest winter of the period was detected. This study suggest that the warming in winter can increase CO2 uptake of the paludified spruce forests of southern taiga in non-growing season. [ABSTRACT FROM AUTHOR]