| Summary: | Northern peatlands play a significant role in the global carbon (C) cycle by functioning as sources of atmospheric methane (CH4). Peatlands are becoming polluted as a result of nitrogen (N) deposition, which is likely to impact CH4 dynamics. This thesis presents research at the Mer Bleue bog (Ottawa, Canada) in the longest known simulated atmospheric nutrient deposition experiment. After 8 years of simulated N (and other nutrient) deposition, activities of microbial communities involved in CH4 cycling have been analyzed in the laboratory and CH4 fluxes measured using chamber techniques in the field. High rates (>10 times ambient deposition) of simulated N deposition decreased CH4 production, and enhanced CH4 oxidation in vitro. However, in situ CH4¬ emissions were greater in the high N plots. I hypothesize that CH4 production is therefore driven by short-lived root exudates in the field, consistent with increased shrub biomass that occurs concomitantly with high N deposition.
|
|---|
