[M-IS01] ENVIRONMENTAL, SOCIO-ECONOMIC, AND CLIMATIC CHANGES IN NORTHERN EURASIA

[MIS01-01] Long-term seasonal dynamics of soil CO₂ emission in pine forest ecosystems of Central Siberia: severe variations in precipitation conditions

*Anastasia Makhnykina^1,2, Eugene Vaganov^2,1, Alexey Panov¹, Daria Polosukhina^1,2, Anatoly Prokushkin^1,2 (1.V.N. Sukachev Institute of forest Siberian Branch of the Russian Academy of Sciences, Krasnoyarsk, Russia, 2.Siberian Federal University, Krasnoyarsk, Russia)

Keywords:boreal forest, soil emission, climate change, Siberia, precipitation, carbon sink

Boreal forests are the large sink of atmospheric CO2 and characterize as a sensitive area to any external factors. Ongoing climate change and enhanced human impacts may conduct irreversible changes in functioning of boreal regions converting them to additional source of CO2. The soil CO2 emission is the second largest flux in the forest ecosystem. Current extreme variations in precipitation conditions, as the main limiting factor for all biogeochemical processes in boreal forests, possibly will significantly modify the soil emission rates. The main goal of this research was to clarify the influence of seasonal precipitation regime on the soil CO2 emission fluxes during snow-free period in the pine forest ecosystems of Central Siberia. We analyzed long-term soil emission data from June to September which started in 2012. Our research sites were located in lichen and feathermoss pine forests with the observable differences in soil moisture content values. To characterize the precipitation conditions we used the hydrothermal coefficient (HTC) of G. Selyaninov (Selyaninov, 1928). Based on HTC we divided our seasons to two groups: (1) HTC > 1.0, “wet seasons”: 2015, 2017, 2019-2022; (2) HTC < 1.0, “dry seasons”: 2012, 2013, 2016, 2018. It was found that in wet seasons the soil CO2 emission rates on average 2-fold higher than in dry seasons with the strong peak of the emission rate in the middle of the season. Interestingly, in the lichen pine forest during dry seasons the soil emission is generally demonstrated the peak of the CO2 fluxes in the second half on the season when observed an increase of precipitation. In the feathermoss pine forest soil CO2 emission rates in dry seasons were 25% higher than in lichen pine forests. However, in wet seasons the soil emission rates were quite similar for two forest types. The obtained results underline the importance of the precipitation conditions of the exact year in control and modification of the soil CO2 emission rates in boreal regions. This study has been supported by the grants the Russian Science Foundation, RSF 24-14-20026.