PARENT SESSION
Poster Session 32: Biogeochemistry
Thursday, August 11, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Emission of nitrous oxide through a snowpack in ten types of ecosystems in Japan.

Yashiro, Yuichiro^*,1, Mariko, Shigeru², Koizumi, Hiroshi¹, ¹ Institute for Basin Ecosystem Studies, Gifu University, Gifu, Gifu, Japan² Institute of Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan

ABSTRACT- The release of N2O from the snow surface in winter and from the soil in summer was measured in various cool–temperate ecosystems (bare ground, grassland, forest, marsh, and crop field) in Japan. The closed chamber method (CC–method) was used for summer measurements and Fick′s diffusion model (DM–method) was used for winter measurements. The snow–covered crop field emitted by far the largest amount of N2O (67.5–70.8 g N2O m^-2 h^-1) in winter. Among snow–covered natural ecosystems, marshy ecosystems had the largest effluxes of N2O (6.3–12.7 g N2O m^-2 h^-1). In summer, the crop field N2O efflux averaged over 1000 g m^-2 h^-1, which was much higher than those of the other ecosystems. Moreover, of the natural ecosystems, the marshy ecosystems had relatively large effluxes of N2O in summer (15.3– 48.9 g N2O m^-2 h^-1), as well as in winter. No emissions of N2O were detected from the bare ground, grassland, or forest ecosystems in summer . Overall, the N2O emissions in winter were analogous to those in summer. The winter to summer ratio of N2O emissions was estimated to be from about 6.7% to 7.0% in crop field, and from about 7.1% to 57.0% in marshes. These results suggest that crop fields and marshy ecosystems play an important role in the annual N2O budget during the snowy season as well as growing season.

Key words: N2O, snow cover, closed chamber method, Fick′s diffusion model