Greenhouse gas emissions from a temperate peatland pasture
Tuesday, February 8, 2011 at 6:59PM Teh, Y. A., W. L. Silver, O. Sonnentag, M. Detto, M. Kelly, and D. D. Baldocchi. 2011. Large Greenhouse Gas Emissions from a Temperate Peatland Pasture. Ecosystems 14: 311–325
We report greenhouse gas fluxes (CH4, CO2, N2O) from a drained peatland in the Sacramento-San Joaquin River Delta, California, USA currently managed as a rangeland (that is, pasture). This ecosystem was a net source of CH4 (25.8 ± 1.4 mg CH4-C m-2 d-1) and N2O (6.4 ± 0.4 mg N2O-N m-2 d-1). Methane fluxes were comparable to those of other managed temperate peatlands, whereas N2O fluxes were very high; equivalent to fluxes from heavily fertilized agroecosystems and tropical forests. Ecosystem scale CH4 fluxes were driven by ‘‘hotspots’’ (drainage ditches) that accounted for less than 5% of the land area but more than 84% of emissions. Methane fluxes were unresponsive to seasonal fluctuations in climate and showed minimal temporal variability. Nitrous oxide fluxes were more homogeneously distributed throughout the landscape and responded to fluctuations in environmental variables, especially soil moisture. Elevated CH4 and N2O fluxes contributed to a high overall ecosystem global warming potential (531 g CO2-C equivalents m-2 y-1), with non-CO2 trace gas fluxes offsetting the atmospheric ‘‘cooling’’ effects of photoassimilation. These data suggest that managed Delta peatlands are potentially large regional sources of greenhouse gases, with spatial heterogeneity in soil moisture modulating the relative importance of each gas for ecosystem global warming potential. Journal Link. Pdf Download.
Key words: methane; nitrous oxide; carbon diox- ide; global warming potential; drained temperate peatland; management; agricultural conversion; Sacramento-San Joaquin Delta.