10:00 AM - 10:15 AM
[MIS01-05] Net ecosystem exchange at West Siberian peatlands from eddy covariance and automatic chamber observations
Keywords:net ecosystem exchange, eddy-covariance, peatlands, Western Siberia
Western Siberian peatlands contain a huge carbon reserves and in their natural state are an effective sink for carbon dioxide and a significant source of methane. The observed climate changes lead to changes in the heat and moisture budgets of wetlands, which in turn determine the carbon cycle, the magnitude and direction of carbon dioxide and methane fluxes.
The results of observations of greenhouse gas, heat and moisture fluxes at the Mukhrino scientific field station in 2022-2023 (Khanty-Mansi Autonomous Okrug-Yugra, Russia) and Plotnikovo station (Tomsk Region, Russia) are presented. Daily and annual dynamics of carbon dioxide fluxes, components of heat and radiation balance, bog water levels and soil temperature of ridge -hollow bog complexes in the middle and southern taiga of Western Siberia were studied.
Carbon dioxide, heat and water vapour fluxes were measured using the eddy-covariance technique. Measuring systems based on Licor infrared gas analysers (Li-7200, Li-7500) and uSonic-3 Cage MP ultrasonic anemometer were installed on 2-10 m towers above the bog surface. Data on the intensity of net ecosystem exchange for 2022-2023 were accumulated. Observational data were processed in EddyPro software using standard corrections. There are numerous omissions in the results of eddy-covariance measurements due to both interruptions in equipment operation and filtering of incorrect data under conditions of weak turbulent mixing. For correct estimation of annual flux sums, the data gaps were filled using the REddyProc package. The same package was used to filter the data by u* and to divide the fluxes into components (GPP, ER).
According to measurements at Plotnikovo station (PLT), the net ecosystem exchange (NEE) from May to September 2023 is negative and ranges from -14.7 to -42.6 gC/m2 per month. In October 2023, almost zero carbon sequestration (-0.3 gC/m2) was obtained. The annual course of NEE fluxes in 2023 differs significantly from 2022, when the maximum carbon uptake (-36.1 gC/m2) was in June, and the bog was a carbon source in September (+8.8 gC/m2) and October (+20.6 gC/m2). In total, during the warm period (May-September), the bog ecosystem accumulated 154.2 gC/m2 in 2023, twice as much as in 2022 (78.2 gC/m2). The large difference is due to the warm and prolonged autumn of 2023, when sphagnum mosses probably continued to grow.
According to eddy-covariance observations at Mukhrino station (Figure 1) from April to September 2023 the total accumulation was 118.8 gC/m2 at the ridge-hollow complex (MUH1), and 151.5 gC/m2 at the pine-shrub-sphagnum bog (MUH2). At the same time, 272.6 and 392.5 gC/m2 were released to the atmosphere with ecosystem respiration, while vegetation during photosynthesis absorbed 392.3 and 544 gC/m2 at MUH1 and MUH2, respectively. Both studied wetland complexes acted as atmospheric carbon sinks from May to September, with the highest uptake at station MUH1 obtained in July (43.3 gC/m2) and at station MUH2 in June (54.7 gC/m2). In 2022, the total carbon uptake for the growing season at the ridge -hollow complex (MUH1) was estimated to be 112.5 gC/m2, and the bog accumulated 82.8 gC/m2 during the whole year.
Thus, all studied bog ecosystems are sink for atmospheric carbon, but the intensity of this sink is determined to a greater extent by vegetation characteristics and weather conditions.
The results of observations of greenhouse gas, heat and moisture fluxes at the Mukhrino scientific field station in 2022-2023 (Khanty-Mansi Autonomous Okrug-Yugra, Russia) and Plotnikovo station (Tomsk Region, Russia) are presented. Daily and annual dynamics of carbon dioxide fluxes, components of heat and radiation balance, bog water levels and soil temperature of ridge -hollow bog complexes in the middle and southern taiga of Western Siberia were studied.
Carbon dioxide, heat and water vapour fluxes were measured using the eddy-covariance technique. Measuring systems based on Licor infrared gas analysers (Li-7200, Li-7500) and uSonic-3 Cage MP ultrasonic anemometer were installed on 2-10 m towers above the bog surface. Data on the intensity of net ecosystem exchange for 2022-2023 were accumulated. Observational data were processed in EddyPro software using standard corrections. There are numerous omissions in the results of eddy-covariance measurements due to both interruptions in equipment operation and filtering of incorrect data under conditions of weak turbulent mixing. For correct estimation of annual flux sums, the data gaps were filled using the REddyProc package. The same package was used to filter the data by u* and to divide the fluxes into components (GPP, ER).
According to measurements at Plotnikovo station (PLT), the net ecosystem exchange (NEE) from May to September 2023 is negative and ranges from -14.7 to -42.6 gC/m2 per month. In October 2023, almost zero carbon sequestration (-0.3 gC/m2) was obtained. The annual course of NEE fluxes in 2023 differs significantly from 2022, when the maximum carbon uptake (-36.1 gC/m2) was in June, and the bog was a carbon source in September (+8.8 gC/m2) and October (+20.6 gC/m2). In total, during the warm period (May-September), the bog ecosystem accumulated 154.2 gC/m2 in 2023, twice as much as in 2022 (78.2 gC/m2). The large difference is due to the warm and prolonged autumn of 2023, when sphagnum mosses probably continued to grow.
According to eddy-covariance observations at Mukhrino station (Figure 1) from April to September 2023 the total accumulation was 118.8 gC/m2 at the ridge-hollow complex (MUH1), and 151.5 gC/m2 at the pine-shrub-sphagnum bog (MUH2). At the same time, 272.6 and 392.5 gC/m2 were released to the atmosphere with ecosystem respiration, while vegetation during photosynthesis absorbed 392.3 and 544 gC/m2 at MUH1 and MUH2, respectively. Both studied wetland complexes acted as atmospheric carbon sinks from May to September, with the highest uptake at station MUH1 obtained in July (43.3 gC/m2) and at station MUH2 in June (54.7 gC/m2). In 2022, the total carbon uptake for the growing season at the ridge -hollow complex (MUH1) was estimated to be 112.5 gC/m2, and the bog accumulated 82.8 gC/m2 during the whole year.
Thus, all studied bog ecosystems are sink for atmospheric carbon, but the intensity of this sink is determined to a greater extent by vegetation characteristics and weather conditions.