Interannual variability of ecosystem exchange of CO2 and H2O in the middle taiga cowberry-lichen pine forest in the European north-east of Russia
S. V. ZAGIROVA, M. N. MIGLOVETS
Komi Science Centre of the Ural Branch of the Russian Academy of Sciences, Institute of Biology, Syktyvkar, Russia
Keywords: cowberry-lichen pine forest, carbon dioxide, evapotranspiration, ecosystem exchange
Abstract
Extreme weather events change the diurnal and seasonal variations in CO2 fluxes between the forest and the above surface atmosphere. The analysis of interannual variability of net CO2 exchange (NEE), total ecosystem respiration (TER), gross ecosystem photosynthesis (GEP) and evapotranspiration (ET) in a cowberry-lichen pine forest of the middle taiga subzone was performed under different weather conditions during the 2021-2023 growing season. According to measurements by eddy covariance system, in the pine forest over three years of observations, the total NEE in May-August varied from -653 to -980 g CO2/m2, GEP varied from 1711 to 2360 g CO2/m2, TER - from 913 to 1380 g CO2/m2. The total evapotranspiration corresponded to 137-262 mm, and the GEP/ET ratio varied within 1.8-3.9 mgC/g H2O. As a result of multi-level statistical analysis, a correlation GEP with gross radiation, temperature and humidity in the growing season was revealed. A relationship between GEP and air temperature and humidity characteristics of the growing season was revealed. GEP and NEE decreased at abnormally high temperatures and a long absence of precipitation in the first half of the 2021 growing season. Maximal effect of air temperature on ecosystem CO2 exchange was observed in 2023 at increased supply of soil moisture. It was concluded that the water reserve in the soil mitigates the negative effect of atmospheric moisture deficit in the summer on photosynthesis and evapotranspiration and thereby ensures a stable seasonal net sink of CO2 in the ecosystem of the cowberry-lichen pine forest of the middle taiga subzone.
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