The National Institute for Environmental Studies began monitoring of carbon dioxide (CO₂) concentrations in the interior of the Siberian taiga using a tower with the cooperation of Russian research organizations at the beginning of the 21st Century (Photo 1). The Siberian taiga is the world’s largest terrestrial ecosystem, and it is believed that its respiration and photosynthesis have a great impact on the fluctuation of CO₂ concentrations. Until the start of these monitoring activities, temporal and spatial monitoring data for Siberia was scarce due to the difficulties imposed by both the harsh natural environment and infrastructure issues. After a process of trial and error, the researchers from NIES were able to develop a stable automatic monitoring system which could operate even under severe conditions, and they have, for the first time in the world, succeeded in obtaining continuous CO₂ data from inner Siberia. This newly developed tower monitoring system at its height covered nine locations, and currently measurements of CO₂ concentrations are carried out in a variety of environments such as taiga, steppe and wetland (Figure 1, Table 1). “Station” itself implies a place where monitoring is conducted, and since this project is carried out with Japanese-Russian collaboration, it has been named JR-STATION (Japan-Russia Siberian Tall Tower Inland Observation Network). With the cooperation of Russian researchers, the system had been further improved by adding a methane sensor to the monitoring system (Photos 2 and 3). The most extensive wetland area in the world is situated in West Siberia, and it is believed that the amount of methane emitted from there is the largest in the world. The methane emissions from Siberia have a great impact on global methane concentrations.

We measured the vertical distributions of CO₂ concentrations using a small airplane for the skies above the tower. A comparative analysis with the data obtained from the tower observation system allowed us to evaluate the representativeness of tower data and estimate the CO₂ uptake by the forest (Photos 4–6). We are carrying out research to accurately elucidate the annual variation of CO₂ uptake in the entire Siberian region using the data of this extensive tower monitoring network.