Influences of Hillslope biogeochemistry on anaerobic soil organic matter decomposition in a tundra watershed

We investigated rates and controls on greenhouse gas (CO2 and CH4) production in two contrasting water-saturated tundra soils within a watershed near Nome, Alaska, United States. Three years of field sample analysis have shown that soil from a fen-like area at the base of the hillslope had higher pH and higher porewater ion concentrations than soil collected from a bog-like peat plateau at the top of the hillslope. The influence of these contrasting geochemical and topographic environments on CO2 and CH4 production was tested in soil microcosms by incubating both the organic- and mineral-layer soils anaerobically. Our results also indicate that inorganic N concentrations were lower and soil C decomposition was more N-limited in the peat plateau soils than the toeslope soils, which exhibited net N mineralization while the peat plateau soils had net N immobilization.