Seasonal variation of concentration and net CO2 exchange in the spruce forest ecosystem of the middle taiga
S.V. Zagirova, J.F. Mikhailov
Section: Ecology and climate change
Measurements of CO2 concentration in atmospheric air and CO2 fluxes over the forest canopy were carried out to quantify ecosystem net exchange (NEE) in spruce stands during the growing season of 2017. In the conditions of cool and rainy summer, the rate of net CO2 exchange between the spruce forest and the surface atmosphere varied from -15.0 to 15.0 gCO2 /(m2 · day), the cumulative NEE from May to August was -780 gCO2 /m2 . In the second half of August the spruce forest became a source of CO2 release into the atmosphere. The change in the CO2 concentration in the air column was approaching zero and did not affect the accumulation of ecosystem exchange. Measurements at eight heights of spruce stands showed a gradual decrease in CO2 concentration in the first half of the growing season, the minimum values were noted in July and August, during the period of maximum photosynthesis of forest trees. The main source of CO2 is soil, respectively, the maximum concentrations are noted in the ground layer of air. The amplitude of seasonal fluctuations in the CO2 content in the air at a height of 0.5 m was 92 ppm, at 2.5 m – 67 ppm, and in the crown space did not exceed 47 ppm. The rate of turbulent air mixing and photosynthetic activity of the canopy of the stand determined the daily changes in the concentration gradient according to the altitude profile of the phytocenosis. Decrease of CO2 in the air column 0–30 m after sunrise and before noon corresponded to an increase in net exchange in the ecosystem of forest. The results of one year of observations indicate that the spruce forest ecosystem performs the function of a sink of carbon dioxide, however,
to assess the interannual variability of net exchange, continuous long-term measurements are required.
Keywords: spruce forest, middle taiga, surface layer of atmosphere, carbon dioxide net exchange, eddy-covariance
Article published in number 3 for 2022 DOI: 10.25750/1995-4301-2022-3-226-234
ISSN 1995-4301
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