Scientists estimate methane emissions from an abandoned peatland
Scientists at BFU named after Kant Immanuel found out that drained peatlands remain a significant source of greenhouse gas methane after terminating peat mining activity. Therefore, the emissions turn out to be heterogeneous and depend on the groundwater level and vegetation type of that specific piece of terrain. The researchers arrived at this conclusion after having been measuring methane emissions for three years at an abandoned peatland within Rossyanka Carbon Supersite in the Kaliningrad region. The findings will help calculate more accurately the contribution of such ecosystems to climate change, as well as be useful in developing strategies of their restoration. The results of the study are published in Land journal.
Peat bogs and places with turf deposits, commonly called peatland, occupy a mere 3% of total land. However, they accumulate about 30% of all carbon contained in all of the world's soil. Because the carbon there is in a carbon state, — in the form of organic compounds, — peatlands play an important role in climate stabilization. When the peatlands are drained, they convert from carbon sink to its source. This is due to the fact that organic matter decomposes with the release of carbon dioxide into the atmosphere — the main contributor to the greenhouse effect. Another greenhouse gas — methane — is normally constantly released from natural swamps, yet when drained, its emission in one of the areas decrease while increasing in other areas. This data differs in various regions, and for different territories, including Russia, the exact amount of greenhouse gases emitted by abandoned peatlands after draining and production remains unknown. This slows down the development of measures to restore these ecosystems and reduce the emissions.
Scientists from Immanuel Kant Baltic Federal University (Kaliningrad) together with colleagues from Institute of Monitoring of Climatic and Ecological Systems of the Siberian Branch of the Russian Academy of Sciences IMCES SB RAS (Tomsk) had been measuring methane emissions from the surface of an abandoned peatland in the Kaliningrad Region between 2022 and 2024. Between the 1970-s and 1990-s, turf mining took place at the study area, and for this purpose the peatland was drained. The production site had subsequently never been reclaimed. In 2021 this peatland became part of a Rossyanka Carbon Supersite established under an eponymous federal program.
For the analysis, the authors selected ten areas with different vegetation cover and moisture levels: open sites with bare peat; parts with green moss fragments; birch coppice sites; reed beds and stretches with recurrent floods.
Every month within a period of three years the scientists installed plastic cameras on these selected areas that allowed to isolate a small area from the external environment. Researchers then took air samples from these chambers and measured the methane concentration. In addition, the authors assessed the air and soil temperature, the level of water tables and rainfall.
It turned out that methane emissions vary considerably at different sites. Most intensively — up to 213 kilograms of gas per hectare a year — the gas was emitted by drainage ditches overgrown with mosses. The drier patches, overgrown with rare birches and small bushes, had minimal amounts of methane flux — less than 10 kilograms per hectare a year. Moreover, the authors discovered that open sites with bare peat do not emit methane at all during warm seasons. On the contrary, they absorbed the gas in small amounts.
Scientists came to the conclusion that emissions depend on the level of groundwaters. Thus, the closer the water is to the surface, the thinner is the turf layer where methane oxidation happens. In that case, the methane flux into the atmosphere appear significant. This is supported by the fact that hot July in the summer of 2024 with heavy rainfall in the study area led to a sharp rise in water and, as a result, to highest levels of methane emissions in three years of observations.
"Our study showed that abandoned peatlands can't be regarded as something homogenous from the greenhouse emissions point of view. The acquired data will be helpful for developing more accurate climate change forecasting models. In the future, we plan to summarize such data and assess the intensity of the carbon footprint as well as study in more detail the dependence of both greenhouse gases on peatland environmental factors. Using the required calculations, it will be possible to scale the results of the study and to assess peatland emissions in other regions", — says Maxim Napreenko, a candidate of biological sciences, senior researcher of the "Geoecology and Marine Environmental Management" Research Centre at BFU named after Kant Immanuel.
More information:
doi.org/10.3390/land14091840
Provided by Immanuel Kant Baltic Federal University
