[B-BC02] Methane in terrestrial and aquatic ecosystems: from microbes to the atmosphere

[BBC02-P01] Seasonal and daily variation of methane emissions from the stem surfaces of Alnus japonica

*Kenshi Takahashi¹, Ayaka Sakabe³, Wakana Azuma², Masayuki Itoh⁴, Yoshiko Kosugi³ (1.Research Institute for Sustainable Humanosphere, Kyoto University, 2.Graduate School of Agricultural Science, Kobe University, 3.Graduate School of Agriculture, Kyoto University, 4. School of Human Science and Environment, University of Hyogo)

Keywords:CH4, woody stem, methanogens

Methane (CH4) is recognized as one of the most important greenhouse gases in the present Earth’s atmosphere, and thus identifying the source distributions and quantifying the emission strengths are a crucial issue. An important source of CH4 from terrestrial areas is known to be microbial origin, especially in wetland soils. Recent studies suggest that tree stems in certain environments can emit CH4. In our study, to explore the mechanisms responsible for CH4 emission from the stem surfaces of Alnus japonica in a riparian wetland, year-round measurements of stem CH4 emission rates and sap flux were conducted. CH4 emission rates were obtained by a closed-chamber method, showing an interesting feature of diurnal variations with a seasonality. Possible mechanisms for CH4 emission will be discussed.