The role of microorganisms in the carbon cycle of the various soil ecosystems

1994 Fiscal Year Final Research Report Summary

• Project/Area Number: 05680447
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: Environmental dynamic analysis
• Research Institution: HIROSHIMA UNIVERSITY
• Principal Investigator: HORIKOSHI Takao Hiroshima Univ.・Fac.Integr.Arts & Sci., Prof., 総合科学部, 教授 (00094102)
• Project Period (FY): 1993 – 1994
• Keywords: Carbon cycle / Soil microbial biomass / Fumigation-extraction method / Turnover time

Research Abstract

Microbial biomass in the soils were determined by the fumigation-extraction method of Vance et al. (1987) in the 3 different forests, Pinus, Quercus and Cryptomeria, in western Japan. Microbial biomass on a ground area basis (kg C/ha) in the A_0 layr of Pinus, Quercus and Cryptomeria forests were 99-110,97-104 and 73-87, respectively, and those in the mineral 0-5 cm layr were 403,324 and 549, respectively.
The turnover times of microbial biomass were estimated by the methods of Tateno (1988) and Joergensen et al. (1990). After 120 days' incuation at 14ﾟC,microbial biomass and respiration rates in the steady state were determined. Using these values, the turnover times (days) in the A_0 layr of Pinus, Quercus and Cryptomeria forests were estimated to be 14-18,1-8 and 11-14, respectively, and those in the mineral 0-5 cm layr were 70-74,45-52 and 110-120, rewpectively.
Then the carbon flows were calculated by using the values of microbial biomass and turnover time. The carbon flow (ton C/ha・yr) in the A_0 layr of Pinus, Quercus and Cryptomeria forests were 2.0-2.9,4.4 and 1.5-2.9, respectively, and those in the mineral 0-5 cm layr were 2.0-2.1,2.3-2.6 and 1.7-1.8, respectively.
The carbon flow thus obtained is comparable to the amount of annual litter fall in each forest, showing quantitatively the important role in the carbon cycle of the forest ecosystems.