Decomposition in extreme-rich fens of boreal Alberta, Canada
Rich fens (minerotrophic peatlands with surface water pH > 5.5) have greater alkalinity and species richness than other boreal peatlands. We used short-term laboratory incubations to quantify CO2 and CH^sub 4^ production in peat from five extreme-rich fens in Alberta. Carbon dioxide production rates averaged 48.29 ± 1.36 µmol CO2 g organic matter^sup -1^ d^sup -1^ across sites and sampling events. Peat from all sites produced CH^sub 4^ during anaerobic incubations, leading to average anaerobic CH^sub 4^ production rates of 359.53 ± 138.7 nmol CH^sub 4^ g organic matter^sup -1^ d^sup -1^. However, methane frequently was consumed (oxidized) during aerobic incubations, leading to aerobic CH^sub 4^ consumption rates averaging 75.2 ± 63.7 nmol CH^sub 4^ g organic matter^sup -1^ d^sup -1^ across sites. Calculated rates of dissolved H^sub 2^CO^sub 3^ + HCO^sup -^^sub 3^ production averaged 59.7 ± 13.4 µmol g organic matter^sup -1^ d^sup -1^, suggesting that dissolved inorganic C is important to the overall C fluxes in these rich fens. Our results suggest that changing hydrologic conditions will influence the balance between methanogenesis and methanotrophy in rich fens, but that surface water chemistry, likely influenced by marl precipitation, also is important to decomposition. Rich fens are estimated to represent the most common wetland type in Alberta, and these peatland ecosystems could play an important role in trace gas emissions across boreal regions.