Changes in net ecosystem exchange of CO2, latent and sensible heat fluxes in a recently clear-cut spruce forest in western Russia: results from an experimental and modeling analysisстатья
Статья опубликована в высокорейтинговом журнале
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Аннотация:Ecosystem carbon dioxide, energy, and water fluxes were measured using eddy covariance in a
fresh clear-cut surrounded by a mixed spruce-birch-aspen forest in the boreal zone of European
Russia. Measurements were initiated in spring 2016 following timber harvest and continued for
five months. The influence of surrounding forest on air flow and turbulent fluxes within the
clear-cut were examined using a process-based two-dimensional (2D) hydrodynamic turbulent
exchange model. The clear-cut was a source of CO2 to the atmosphere prior to onset of
vegetation growth during early spring. During this period the mean daily latent (LE) and sensible
(H) heat fluxes were very similar and the Bowen ratio (b = H/LE) averaged about 1.0. Daily net
ecosystem exchange of CO2 (NEE) was around 0 gC m2 d1 following onset of vegetation
growth from mid-spring through summer, while b declined to 0.6–0.7. 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. Modeled vertical CO2
and H2O fluxes along a transect that crossed the clear-cut and coincided with the dominate wind
direction showed that the clear-cut strongly influenced turbulent fluxes within the atmospheric
surface layer. Furthermore, modeled atmospheric dynamics suggested that the clear-cut had a
large influence on turbulent fluxes in the downwind forest, but little impact on the upwind side.
An aggregated approach including field measurements and process-based models can be a useful
approach to estimate energy, water and carbon dioxide fluxes in non-uniform forest landscapes.