MOSCOW, 31 Oct. Soil burned out during forest fires becomes a source of carbon dioxide, scientists from SibFU and the Krasnoyarsk Scientific Center of the Siberian Branch of the Russian Academy of Sciences came to this conclusion during the study. The results were published in MDPI.
According to scientists from the Siberian Federal University (SFU) and the Krasnoyarsk Scientific Center of the Siberian Branch of the Russian Academy of Sciences, fires radically change the function of forests from absorbers and holders of carbon dioxide to its additional source.
Experts assessed the emission value — the amount of CO2 released from the soil of damaged northern (boreal) forests. To assess the impact of fires on carbon dioxide fluxes, direct observation methods were used — chamber measurements from the soil surface. In this technique, the flow of carbon dioxide from the soil was calculated from the change in concentration in the chamber during the measurement time. The indicators were measured at different stages of post-fire recovery and compared with undisturbed forest areas.
Scientists investigated the middle taiga subzone of Central Siberia. The places where the fire happened a year earlier were examined, as well as the areas of fires that were 14, 23, 46 and 121 years old.
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“A sufficient amount of time must pass since the fire so that the ecosystem can function as usual again. In Russia, natural forest ecosystems of the boreal zone often act as a sink for atmospheric carbon. Whether forests will successfully absorb carbon dioxide is influenced by soil moisture, the rate of ecosystem recovery, and, of course, the time that has passed since the last major fire,” said Anastasia, co-author of the study, senior researcher at the Laboratory of Biogeochemistry of Ecosystems at the Institute of Ecology and Geography of Siberian Federal University. Makhnykina.
She explained that the microclimate parameters of the territory, such as heat and moisture regimes, significantly affect the natural cycle of substances. The surface albedo—the ability to reflect solar energy—changes.
In the area where the last fire was a year ago, the albedo is minimal. After a recent fire, there is no ground cover and the humidity undergoes changes — from drought to waterlogging. According to scientists, forest cover damaged by fire changes the usual metabolism.
«As a result of fires, the surface layer of soil, in which reserves of organic matter are concentrated, burns out substances. Because of this, the functioning of the microbial community is disrupted, fertility is significantly reduced, since the active layer of soil can completely burn out under the influence of high temperatures at the time of a fire. Forest restoration takes an average of 30 years, but the problem is that fires have become more frequent,» she said Makhnykina.
According to the researcher, disruption of secular rhythms can lead to a significant change in the functional role of forest areas. They will turn from an object that absorbs CO2 into its additional source.
The work was carried out as part of the implementation of the most important innovative project of national importance “Development of a system for ground-based and remote monitoring of carbon pools and greenhouse gas flows on the territory of the Russian Federation, ensuring creating a system for recording data on the flows of climate-active substances and the carbon budget in forests and other terrestrial ecological systems.”
The work was supported by the Russian Academy of Sciences within the framework of the state assignment of the Forest Institute of the Siberian Branch of the Russian Academy of Sciences.
Siberian Federal University is a participant in the Russian state program for supporting universities «Priority 2030» of the national project «Science and Universities».