Monitoring of Greenhouse Gas Production on the Landscape Profile of the Vasyugan Swamp

This study deals with the analysis of long-term trends in greenhouse gas concentration, emission, and flows in the landscape profile (LP) of the Vasyugan swamp located in the southern taiga biome in Western Siberia. The autonomous part of the LP is occupied by the sedge–sphagnum swamp; the transitional part, by the dwarf-shrub–sphagnum swamp with low pine trees; and the accumulative part, by the dwarf-shrub–sphagnum swamp with high pine trees. Peat deposit in autonomous and transitional parts of the LP is up to 3 m in thickness, whereas in the accumulative part, up to 1 m. Concentrations of greenhouse gases were determined by the equilibrium diffusion chambers (“peepers”) method, and emissions were determined by the chamber method. It was found that under different climatic conditions the concentration of CO2 in the LP peat deposits varied in the range from 0.01 to 4.2 mmol/dm3; and the concentration of CH4, from 0.01 to 2.19 mmol/dm3. Against the background of an uneven distribution of CO2 and CH4 in peat deposits, a tendency for an increase in their concentrations and a decrease in the amplitude of fluctuations with the depth was revealed. A reliable influence of the botanical composition of peat on the profile activity of the studied gases was determined. The temporal variability of greenhouse gas concentrations in the upper layer of LP peat deposits was greatly affected by the weather conditions: the maximum values of CO2 concentrations were more often recorded in July and of CH4 concentrations, in May and September. The CO2 emission in LP peat deposits during the 8-yr-long observation period ranged from 3.9 to 160.3 mg CO2/(m2 h); and CO2 flows, from 17 to 120.5 g C/(m2 yr); CH4 emission varied from –3.0 to 10.7 mg CH4/(m2 h); and CH4 flows, from 0.5 to 6.7 g C/(m2 yr). At all observation points of the LP, maximum CO2 flows and minimum CH4 flows were recorded in a dry year with the annual hydrothermal index of 0.9. The flows of CH4 consistently increased from the accumulative to the transit and then to the autonomous part of the LP irrespectively of the hydrothermal conditions of particular year.