Abstract The response of soil carbon availability and microbial utilization efficiency to varying vegetations and to increasing temperature emphasizes the need for further research in volcanic forest soils. We have studied responses of soil microbial biomass C (MBC) concentrations and metabolic quotients (qCO2, CO2-C / biomass-C) to vegetations and temperature in temperate volcanic forest soils. Soils were sampled in April and October 2003 beneath four forest stands in close proximity (200 m apart) in central Japan: a Japanese cedar coniferous forest (CI), a pine coniferous forest (CII), and an oak-dominated hardwood on a grading and steep slope (DI and DII). The soil MBC concentrations and qCO2 values beneath each forest stand were measured under oxic conditions, along with the effect of temperature and the long-term storage at low temperature on both variables. Comparing different forest stands, it was indicated that the pine forest soil always showed the lowest MBC concentration relative to soil total C, and the largest qCO2 (P