The bogs of Western Siberia are considered one of the world’s largest natural carbon stores: they have been accumulating carbon in the form of peat deposits for millennia. Thanks to this, Western Siberian bogs actively contribute to the carbon cycle, absorbing carbon dioxide and releasing methane. At the same time, the intensity of greenhouse gas exchange largely depends on the temperature at the surface of the bog, its topography and soil moisture.
The effect of these factors on greenhouse gas fluxes has been considered by the scientists from the Obukhov Institute of Atmospheric Physics RAS, who chose to study a raised bog typical of Western Siberia: the Mukhrinsky peat bog in the Khanty-Mansi Autonomous Okrug (AO). The authors conducted an expedition, during which they described the topography and surface temperature of the bog, observing the area using a drone. The scientists also estimated the amount of methane emissions from various microlandscapes of the bog and carried out the most detailed measurements of heat and moisture flows to date.
As a result, the authors identified vastly different microlandscapes, such as ryams (elevated areas covered with shrubs or short trees); ridges (tussocks covered with moss); and swamps and hollows (low-lying waterlogged territories). Daytime and nighttime temperatures at the surface of the bog varied greatly: the difference between the higher elevations and the cold, low-lying, flooded areas was about 10 degrees Celsius. This is due to the fact that water warms up more slowly than air, which is why wet soils tend to have a lower temperature.
The amount of methane released from different microlandscapes of the bog also varied. For instance, CH4 emissions at higher elevations – in rows and ridges – were 150 times lower than in lowlands (0.07 and 11 milligrams of methane per square meter per hour, respectively). As a result, the scientists came to the conclusion that models for calculating greenhouse gas fluxes in bogs should take into account spatial heterogeneity.
“Our study will be useful in building correct models for the release and absorption of greenhouse gases by bogs, as well as in predicting these processes under climate change. In addition, understanding the processes of moisture, heat and gas exchange between bogs and the atmosphere is important when draining or restoring disturbed bogs,” Dmitry Chechin, candidate of physical and mathematical sciences, senior researcher at the Institute of Atmospheric Physics RAS, is quoted as saying by the Russian Science Foundation.