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Methane Emissions from a Subtropical Grass Marshland, Northern Taiwan

Abstract

Methane (CH4) is an important greenhouse gas and a significant contributor to global warming. Compared to preindustrial levels, the atmospheric CH4 concentration has more than doubled. The most dominant non-anthropogenic sources of atmospheric CH4 have been found to be natural wetlands, but CH4 fluxes from many wetlands all over the world are largely unexplored. We present the first results of eddy covariance CH4 flux measurements above a subtropical grass marshland in northern Taiwan. Our results show that this wetland, dominated by Phragmites australis and Brachiaria mutica, is a significant source of CH4. During the six-week measuring period in August and September, daily mean emissions of 145 mg CH4 m−2 were recorded. Clear diurnal variations of the CH4 fluxes were observed, peaking at 0.187 μmol m−2 s−1 in the early afternoon. Minimal emissions generally occurred between 03:30 and 06:30 h, before sunrise. Significant correlations of the CH4 flux with the latent heat flux, stomatal conductance, and relative humidity indicated that the diurnal patterns were induced by convective gas flow through the aerenchyma of the plants. Moreover, the magnitude of the CH4 emissions predominantly responded to water level fluctuations; water levels below the soil surface were associated with significantly lower CH4 emissions.

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Acknowledgments

We would like to thank Chao-Jung Fan and Ziyi Lu (National Taiwan University) for support during the setup of the eddy covariance tower and technical assistance both during and after our measuring period. We thank C. Brennecka for language-editing of the final version of the manuscript.

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Correspondence to Katharina Philipp.

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Philipp, K., Juang, JY., Deventer, M.J. et al. Methane Emissions from a Subtropical Grass Marshland, Northern Taiwan. Wetlands 37, 1145–1157 (2017). https://doi.org/10.1007/s13157-017-0947-8

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  • DOI: https://doi.org/10.1007/s13157-017-0947-8

Keywords

  • Methane fluxes
  • Subtropical wetland
  • Eddy covariance
  • Greenhouse gases
  • Diurnal pattern
  • Plant-mediated transport