A 1-year greenhouse gas budget of a peatland exposed to long-term nutrient infiltration and altered hydrology: high carbon uptake and methane emission

摘要

Long-term increased nutrient influx into normally nutrient-limited peatlands in combination with altered hydrological conditions may threaten a peatland's carbon storage function and affect its greenhouse gas (GHG) budget. However, in situ studies on the effects of long-term altered conditions on peatland functioning and GHG budgets are scarce. We thus quantified GHG fluxes in a peatland exposed to enhanced water level fluctuations and long-term nutrient infiltration in Ontario, Canada, via eddy-covariance and flux chamber measurements. The peatland was a prominent sink of - 680 +/- 202 g carbon dioxide (CO2) and a source of 22 +/- 8 g methane (CH4) m(-2) year(-1), resulting in a negative radiative forcing of - 80 g CO2 eq. m(-2) y(-1). During the growing season CH4 fluxes were constantly high (0.1 g m(-2) s(-1)). Further, on three dates, we measured nitrous oxide (N2O) fluxes and observed a small flux of 2.2 mg m(-2) day(-1) occurring during the thawing period. Taking the studied ecosystem as a model system for other peatlands exposed to long-term increased nutrient infiltration and enhanced water level fluctuations, our data suggest that such peatlands can maintain their carbon storage function and CO2 sequestration may outweigh emissions of CH4.