1:45 PM - 3:15 PM
[MIS01-P09] The response of net soil exchange CO2 (NSE) fluxes to the seasonal changes in precipitation in Central Siberia: snow-free period of year
Keywords:soil emission, precipatation, carbon cycle, boreal forest
The boreal forests, as a sink of atmospheric CO2, are an important research area that is largely responsive to current climate change. It has been noted that the soils of boreal forests contain four times more carbon than is concentrated in the entire aboveground phytomass. At the same time, estimates of the sequestration capacity of ecosystems in the boreal zone differ significantly. The process of carbon sequestration is influenced by a number of factors, both natural and anthropogenic, which often lead to additional release of CO2 from boreal forests.
One effect that changes the binding capacity of ecosystems is the "Birch effect" (Birch, 1964). The essence of the effect is that when waterlogged after soil drought, the rate of CO2 emission flux increases.
To date, extreme weather events have become more frequent, such as heavy rainfall or, on the contrary, drought during the summer period. Their influence on natural dynamic processes in ecosystems, including soil CO2 emissions, raises a number of questions.
The main purpose of this work was to evaluate the effect of rainfall on the exchange fluxes of CO2 in the subordinate layer during the snowless period in the pine ecosystems of the boreal zone of Central Siberia.
The studies were carried out on the territory of the Turukhansk district of the Krasnoyarsk Territory on the basis of the station "International Observatory High Mast Station ZOTTO" (https://www.zottoproject.org).
Net soil exchange (NSE) of CO2 during the snowless period was measured using an automated LI-COR system based on an infrared gas analyzer - Li-8100 A (Li-cor Biogeosciences Inc., Linkoln, USA) with a transparent chamber for measuring soil gas exchange (8100- 104C). For each measurement of CO2 flux, the temperature (Soil Temperature Probe Type E (Omega, USA)) and humidity (Theta Probe Model ML2 (Delta T Devices Ltd., UK)) of the soil at a depth of 5 cm were also recorded.
CO2 fluxes (NSE) for the considered time period varied significantly both during the season and between summer seasons (2020-2022). A common feature is the predominance of emission activity over photosynthetic activity during the summer period.
An increase in CO2 fluxes after heavy precipitation (more than 5 mm) was observed by 3–10 times depending on the intensity and duration of rain, and also slightly changing in certain periods of the season. It is interesting that in the waterlogged season (2020) of the year, the peak of CO2 emission falls on the duration of precipitation from 60 to 120 minutes, with different intensity of precipitation, and in the season with a deficit of precipitation (2021), the largest CO2 fluxes are observed at the maximum duration of rain - more than 120 minutes. The dependence of the emission flux on external environmental factors also varies between different seasons and depends on the amount of precipitation per season.
Thus, based on the results of the studied seasons, it can be concluded that during the growing season from the taiga forests of Central Siberia, heavy rains lead to a rapid impulsive response from soil emissions and, as a consequence, the release of an additional amount of CO2 from the soil into the atmosphere.
One effect that changes the binding capacity of ecosystems is the "Birch effect" (Birch, 1964). The essence of the effect is that when waterlogged after soil drought, the rate of CO2 emission flux increases.
To date, extreme weather events have become more frequent, such as heavy rainfall or, on the contrary, drought during the summer period. Their influence on natural dynamic processes in ecosystems, including soil CO2 emissions, raises a number of questions.
The main purpose of this work was to evaluate the effect of rainfall on the exchange fluxes of CO2 in the subordinate layer during the snowless period in the pine ecosystems of the boreal zone of Central Siberia.
The studies were carried out on the territory of the Turukhansk district of the Krasnoyarsk Territory on the basis of the station "International Observatory High Mast Station ZOTTO" (https://www.zottoproject.org).
Net soil exchange (NSE) of CO2 during the snowless period was measured using an automated LI-COR system based on an infrared gas analyzer - Li-8100 A (Li-cor Biogeosciences Inc., Linkoln, USA) with a transparent chamber for measuring soil gas exchange (8100- 104C). For each measurement of CO2 flux, the temperature (Soil Temperature Probe Type E (Omega, USA)) and humidity (Theta Probe Model ML2 (Delta T Devices Ltd., UK)) of the soil at a depth of 5 cm were also recorded.
CO2 fluxes (NSE) for the considered time period varied significantly both during the season and between summer seasons (2020-2022). A common feature is the predominance of emission activity over photosynthetic activity during the summer period.
An increase in CO2 fluxes after heavy precipitation (more than 5 mm) was observed by 3–10 times depending on the intensity and duration of rain, and also slightly changing in certain periods of the season. It is interesting that in the waterlogged season (2020) of the year, the peak of CO2 emission falls on the duration of precipitation from 60 to 120 minutes, with different intensity of precipitation, and in the season with a deficit of precipitation (2021), the largest CO2 fluxes are observed at the maximum duration of rain - more than 120 minutes. The dependence of the emission flux on external environmental factors also varies between different seasons and depends on the amount of precipitation per season.
Thus, based on the results of the studied seasons, it can be concluded that during the growing season from the taiga forests of Central Siberia, heavy rains lead to a rapid impulsive response from soil emissions and, as a consequence, the release of an additional amount of CO2 from the soil into the atmosphere.