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[B-1.7.1 Study on Carbon Flow Caused by Microbial Community in the Soils of Temperate Zone]

[Contact Person]

Mikiya Hiroki
senior researcher
Environmental Microbiology Section, Environmental Biology Division,
National Institute for Environmental Studies
Environmental Agency
Onogawa 16 - 2, Tsukuba, Ibaraki, 305 Japan
Tel: +81-298-50-25 13, Fax: +81-298-51-4732
E-mail: hiroki-m@nies.go.jp

[Total Budget for FY1993-FY1995]

14,101,000 Yen (FY1995; 4,705,000 Yen)

[Abstract]

　To reveal biological and chemical properties of soils which affect the CO₂ evolution from soil, a measuring system for determination of the CO₂ evolution from soil was developed, and CO₂ fluxes from soil surface, litter decomposition, biological and chemical properties of the soils were measured in a deciduous broad-leaved forest in Japan. The CO₂ evolution measuring system examined by flow-through chamber method had the advantage that CO₂ efflux was able to be determined easily in a short time at any field site without an electric power supply or other special equipment. In situ, there was a negative correlation between the CO₂ fluxes and the water content of soil in summer season. 31 % of litter in litter bags was decomposed from June to November. The decomposition rate of the litter decreased in processing of degradation. In laboratory experiment, CO₂ evolution rates from incubated litter were ranged from 51-83 mgC kg^-1h^-1. CO₂ evolution rates from incubated soils collected from 0-5 cm depth layer were ranged 1.2-2.0 mgC kg^-1h^-1, while those of the deeper layer were lower than 0.2 mgC kg^-1h^-1. These results suggest that the CO₂ evolution is carried out at litter and surface layers down to 10 cm depth. CO₂ evolution rates from incubated soils were significantly correlated to the microbial biomass in the soils, which correlated more significantly to nitrogen contents than to the carbon contents in the soils.

[Key Words]

Biomass, CO₂, Organic matter, Microorganisms, Soil respiration