[A-CG37] Biogeochemical cycles in Land Ecosystem

[ACG37-01] Temporal and spatial variation of soil CO₂/CH₄ fluxes in two cool-temperate forests in Japan

*Lifei Sun¹, Naishen Liang¹, Takashi Hirano², Yoshiyuki Takahashi ¹, Munemasa Teramoto³, Kentaro Takagi², Toshiaki Kondo⁴, Jun Koarashi⁵, Mariko Atarashi-Andoh⁵, Reiko Ide¹, Xin Zhao¹, Sachinobu Ishida⁶, Masahiro Takagi⁷, Tomotsugu Yazaki⁸ (1.National Institute for Environmental Studies Japan, 2.Hokkaido University, 3.Tottori University, 4.Japan International Research Center for Agricultural Sciences , 5.Japan Atomic Energy Agency , 6.Hirosaki University, 7.University of Miyazaki, 8.Meji University)

Keywords:Soil carbon fluxes, Chamber, Temporal variation, Spatial variation

Forests cover about 30% of global land surface and the total forest carbon stocks (860 Pg) are responsible for about 45% of the carbon in the terrestrial biosphere. Forest soil carbon fluxes which include CO₂ and CH₄ play an important role in global climate change due to both high soil respiration and CH₄ absorption. Consequently, clarifying of mechanisms in forest soil carbon fluxes is critical for understanding the future global carbon cycle and climate change.
To investigate soil CO₂/CH₄ fluxes, we installed multi-channel automated chamber measurement systems in two cool-temperate forests of Tomakomai (natural recovered forest following the typhoon in 2004) of Hakkaido and Fuji-Hokuroku (65-year-old larch plantation) of central Japan. The chambers were separated into 3 groups each with control, trenching and covering understory treatment, respectively. Soil carbon fluxes were continuously measured at hourly and two-hour intervals during snow-free season.
In both forests, soil CO₂/CH₄ fluxes showed high seasonal variation. Soil respiration increased exponentially with changing in soil temperature, whereas soil CH₄ uptake was negatively correlated with soil moisture. Though both the soil temperature and moisture were not significant difference between two forests, we found significant larger soil respiration as well as CH4 absorption in Fuji-Hokuroku larch forest as compared with that of Tomakomai natural forest probably due to both the higher root biomass and soil organic carbon.