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Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 7, 3447-3457, 2010
https://doi.org/10.5194/bg-7-3447-2010
© Author(s) 2010. This work is distributed under
the Creative Commons Attribution 3.0 License.
 
05 Nov 2010
Soil CO2 efflux of a larch forest in northern Japan
N. Liang1, T. Hirano2, Z.-M. Zheng3, J. Tang4, and Y. Fujinuma1,5 1Center for Global Environmental Research, National Institute for Environmental Studies, Tsukuba, Ibaraki 305-8506, Japan
2Research Faculty of Agriculture, Hokkaido University, Sapporo 060-0809, Japan
3East China Normal University, Shanghai 200062, China
4The Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA 02543, USA
5Tottori University of Environmental Studies, Tottori 689-1111, Japan
Abstract. We had continuously measured soil CO2 efflux (Rs) in a larch forest in northern Japan at hourly intervals for the snow-free period in 2003 with an automated chamber system and partitioned Rs into heterotrophic respiration (Rh) and autotrophic respiration (Rr) by using the trench method. In addition, we applied the soil CO2 concentration gradients method to continuously measure soil CO2 profiles under snowpack in the snowy period and to partition Rs into topsoil (Oa and A horizons) CO2 efflux (Ft) with a depth of 0.13 m and sub-soil (C horizon) CO2 efflux (Fc). We found that soil CO2 effluxes were strongly affected by the seasonal variation of soil temperature but weakly correlated with soil moisture, probably because the volumetric soil moisture (30–40% at 95% confidence interval) was within a plateau region for root and microbial activities. The soil CO2 effluxes changed seasonally in parallel with soil temperature in topsoil with the peak in late summer. On the other hand, the contribution of Rr to Rs was the largest at about 50% in early summer, when canopy photosynthesis and plant growth were more active. The temperature sensitivity (Q10) of Rr peaked in June. Under snowpack, Rs was stable until mid-March and then gradually increased with snow melting. Rs summed up to 79 gC m−2 during the snowy season for 4 months. The annual Rs was determined at 934 gC m−2 y−1 in 2003, which accounted for 63% of ecosystem respiration. The annual contributions of Rh and Rs to Rs were 57% and 43%, respectively. Based on the gradient approach, Rs was partitioned vertically into litter (Oi and Oe horizons) with a depth of 0.01–0.02 m, topsoil and sub-soil respirations with proportions of 6, 72 and 22%, respectively, on an annual basis. The vertical distribution of CO2 efflux was consistent with those of soil carbon and root biomass.

Citation: Liang, N., Hirano, T., Zheng, Z.-M., Tang, J., and Fujinuma, Y.: Soil CO2 efflux of a larch forest in northern Japan, Biogeosciences, 7, 3447-3457, https://doi.org/10.5194/bg-7-3447-2010, 2010.
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