Microbial Biomass in the Soils of Burned and Unburned Japanese Red Pine Forests in the Setouchi District, Western Japan.

Microbial biomass in the soils of burned and unburned Japanese red pine forests in the Setouchi District, Western Japan was determined by a slightly modified chloroform fumigation-incubation method. Averages±standard deviations of microbial biomass carbon (C) of 36 unit samples in the 0-5cm soil layers at burned sites located in Ato and Nenoura were 307±206 and 789±274mg kg-1 dry soil, respectively, and that at an unburned site at Ato was 408±213 mg kg-1 dry soil. Soil microbial biomass C at the burned sites were approximately the same or slightly higher than at the unburned site. In contrast with soil microbial biomass, the above-ground plant biomass at the burned sites was about one-fifth or one-sixth of that at the unburned site. Microbial biomass C in the FH layer at the unburned site at Ato was 13.38±6.13g kg-1 dry soil. No significant fluctuations of microbial biomass were observed through 1 year in the 0-5cm soil layers at either the burned and unburned sites, nor in the FH layer at the unburned site. The ratios of microbial biomass C to total C in the soils at the burned sites were 3.2-3.3%, significantly higher than those at the unburned site (2.1%). Significant correlations were observed between microbial biomass C and some soil characteristics, such as contents of total C, total nitrogen (N) and water, in both burned and unburned soils.