Northern wetland soils contain about 14% of the global organic carbon and could be considered as important natural sources and sinks of atmospheric methane. Investigations of trace gas fluxes - for example the processes of methane production, transport, oxidation and emission - are only beginning in Middle Siberia.
The important site and soil parameters (precipitation, temperature, acidity, moisture, redox) - which determine the CH4 fluxes - are measured for different soil-plant-complexes. The typical patterned ground and their soils are monitored by soil survey (distribution, structure and decomposition of organic matter in the active layers, soil texture, transition to the permafrost table). The produced and emitted methane - which is formed under anoxic condition in the active layers - are measured by special gas chambers of different wet tundra soils.
The investigation areas are located at the Labaz Lake (72oN, 100oE) and the Levinson Lessing Lake (74oN, 98oE). The lowland of Labaz is characterized by an undulated landform with lake depression. The Levinson Lessing area has hilly to steeply landforms with meandering rivers. The main vegetation types of both sites are a treeless, subarctic tundra differentiated by the soil moisture conditions.
The climate is characterized by mean July air temperature of 12 oC (mean annual air temperature: -13oC) and mean annual precipitation of about 236 mm. Dominant in the Labaz Lake region are gleyic soils with different aquic soil moisture regimes and patterned-grounds are nonsorted polygons, nonsorted circles and earth hummocks. The Levinson Lessing Lake area is dominated by sorted polygons, circles and nets with different organic and gleyic cryosols. The thickness of the thawing layers range between 0.30 and 1.20 m depth.
The CH4 emission rates varied from 2 to 159 mg * m-2 * d-1 depending on the special soil and site parameters. CH4 is mainly produced in the upper few centimeters of soil depth which has higher soil temperatures (about 10 oC) and high water contents. In deeper soil layers with low temperature ( < 3,6 oC) - influenced by the permafrost table - no methane production could be measured. The presented data are the first results of a 3-year project. They indicate that wet tundra soils may play an important role in the global CH4 budget.
Eva-Maria Pfeiffer Institute of Soil Science University of Hamburg Allende Platz 2 20146 Hamburg, Germany Phone: 040.4123.3512 Fax: 040.4123.2024 E-mail: bk3a502@rrz.uni-hamburg.de