CO2 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. 65degrees 36'N, 171degrees 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.