CO<sub>2</sub> flux measurements in Russian Far East tundra using eddy covariance and closed chamber techniques

The objective of this study was to estimate the CO₂ exchange of a tundra ecosystem in the Russian Far East using the eddy covariance technique using closed-chamber measurements as a reference. An eddy covariance tower was placed near the Lavrentiya settlement (Chukotskiy Peninsula, Russia, 65° 36′N, 171°04′W) within a typical tundra landscape. During the 85 d of continuous measurements [Julian days (JD) 205–289, 2000] the CO₂ exchange of the studied ecosystem was found to be close to equilibrium (a carbon sink at 10.2 gC m−2). In the late summer period (JD 205–240) the ecosystem sequestered 32.1 gC m−2, whereas in autumn (JD 241–289), it was functioning as a carbon source of 21.9 gC m−2. Model-based estimates of ecosystem respiration and gross primary production were obtained over the period of observations. These are the first eddy covariance-based measurements performed in the Russian tundra.