Carbon dioxide and methane dynamics and annual carbon balance in tundra wetland in NE Europe, Russia

[1] Methane (CH4) and carbon dioxide (CO2) fluxes on east European tundra wetland ecosystems (67degrees23'N, 63degrees22'E) were measured by static chamber techniques in 1999. The 29 microsites were divided into wet flarks (WF), intermediate flarks (IF), wet lawns (WL), intermediate lawns (IL), and hummocks (HCK) in accordance to the water table (WT) and vegetation. The seasonal net ecosystem exchange (NEE) varied from -104 mg emission to 249 mg CO2-C m(-2) h(-1) uptake. Regression models were constructed to estimate the seasonal gross photosynthesis and respiration on each of the microsites. The cumulative gross photosynthesis (and respiration) was 68 (37), 131 (77), 176 (126), 164 (129), and 189 (187) g C m(-2) in a 100 day summer period in WF, IF, WL, IL, and HCK, respectively. The losses of carbon in winter accounted for 23.7%, 5.0%, 3.1%, 2.6%, and 2.3% of the net ecosystem production. CH4 emissions in summer (and winter) were 7.7 (7.8), 6.6 (0.8), 8.2 (0.4), 0.7 (0.3), and 0.1 (0.2) g C m(-2) for WF, IF, WL, IL, and HCK, respectively. The modeled annual carbon balance for grouped microsites shows that dry HCKs were carbon sources -7.5 g C yr(-1) while flarks and lawns were carbon sinks ranging from 2.2 to 35.9 g C yr(-1). The results show the importance of WT and vegetation composition on annual flux dynamics in a tundra wetland. CH4 emissions from arctic peatlands seem to be sensitive to changes in the WT.