ИСТИНА

Ecosystem carbon dioxide, energy, and water fluxes were measured using eddy covariance and portable chambers in a fresh clear-cut surrounded by a mixed spruce-birch-aspen forest in the boreal zone of European Russia. Measurements started in April 2016 following timber harvest and continued for height months. Results showed that the clear-cut was a permanent source of CO2 to the atmosphere. Total Ecosystem Respiration (TER) and Gross Primary Production (GPP) were about 7.4±3.4 gС∙m-2 and 4.1±3.0 gС∙m-2 per day, respectively. TER derived by eddy covariance technique showed a reasonable accordance with TERch obtained by chamber methods. During the mid-spring the mean daily latent (LE) and sensible (H) heat fluxes were very similar and the Bowen ratio (β=H/LE) averaged about 1.0. During the late spring and summer months the net ecosystem exchange of CO2 (NEE) remained slightly positive following onset of vegetation growth, while β was changing in the range from 0.3 to 0.5. There was strong diurnal variability in NEE, LE and H over the measurement period that was governed by solar radiation and temperature as well as the leaf area index (LAI) of regrown vegetation.