Microbial biomass and microflora in the soils at burned and unburned Japanese red pine forests

Soil microbial biomass was estimated in the burned and unburned Japanese red pine forests by the chloroform fumigation-incubation method. Along with this study numbers of some microbial groups (fungal spores, actinomycetes, total bacteria, gram-negative bacteria and bacterial spores) were investigated in the same soils by dilution plate count technique.Microbial biomass-C in the 0-2cm soil layer at the burned site at Nenoura fluctuated from month to month during the period from February, 1986 to July, 1987 (34-51 months after fire) in the range from 74 2 to 134.9mg/100g dry soil, relatively low during the period from December to April and maximal in October, 1986 and June, 1987. Microbial biomass in the 0-2cm soils at the burned sites at Tennoh (4 months after fire) and Norosan (80 months after fire) and the unburned site at Ato were almost the same level as that at the burned site at Nenoura. In contrast to the relatively small fluctuations of biomass, the numbers of microorganisms, especially those of total and gram-negative bacteria, fluctuated extensively from month to month. The greater numbers of total and gram-negative bacteria appeared in October-December in the 0-2cm soil layer at the burned site and in the FH and 0-2cm soil layer at the unburned site. The numbers of all microbial groups essentially decreased in August to early-September.