Annual variation of CH4 emissions from the middle taiga in West Siberian Lowland (2005–2009):a case of high CH4 flux and precipitation rate in the summer of 2007

We described continuous measurements of CH₄ and CO₂ concentration obtained at two sites placed in the middle taiga, Karasevoe (KRS) and Demyanskoe (DEM), in West Siberian Lowland (WSL) from 2005 to 2009. Although both CH₄ and CO₂ accumulation (ΔCH₄ and ΔCO₂) during night-time at KRS in June and July 2007 showed an anomalously high concentration, higher ratios of ΔCH₄/ΔCO₂ compared with those in other years indicated that a considerably higher CH₄ flux occurred relative to the CO₂ flux. The daily CH₄ flux calculated with the ratio of ΔCH₄/ΔCO₂ and terrestrial biosphere CO₂ flux from an ecosystem model showed a maximum in July at the both sites. Although anomalously high flux was observed in June and July 2007 at KRS, only a small flux variation was observed at DEM. The high regional CH₄ flux in June and July 2007 at KRS was reproduced using a process-based ecosystem model, Vegetation Integrative Simulator for Trace gases (VISIT), in response to high water table depth caused by the anomalously high precipitation during the summer of 2007.