The numbers and biomass of bacteria and fungi obtained by the dilution plate count method and the direct count method by microscopy

The Kasuga-yama Hill Primeval Forest in Japan, a world heritage site, is the sole lowland laurel-leaved forest in the Kansai District where natural conditions have been conserved for more than 1160 years. The properties, especially the microbial ecology, of the soil supporting the primeval forest have not been clarified to date. Therefore, we have started a series of studies for clarifying the soil properties, especially the microbial ecology, of this region. In the present study, the organic layer (L, F and H horizons) and mineral soil layer (A. B and C horizons) of the soil under the laurel-1eaved forest (Dry Brown Forest soil; BD-1), natural Cryptomeria japonica (Dry Brown Forest soil; BD-2) and Hideyoshi Cryptomeria japonica forests (Wet Podzol Soil type; Pw) were selected to examine the physico-chemical properties of the soil and the numbers and biomass of the microorganisms. The obtained results are summarized below. 1)The numbers of bacteria and fungi obtained by the dilution plate count method and the direct count method by microscopy were larger in the organic layer of F and H horizons than in the mineral soil layer. So, it was suggested that active microbial metabolism took place in the organic layer. 2)The number of bacteria obtained by the plate count method was only 0.05% of those counted by the direct count method. So, we found that forest soil contains very numerous non-culturable bacteria, compared with agricultural soil. 3)The numbers of bacteria and the length of fungi hypha obtained by the direct count method were larger in H horizon than in F horizon. So, it was estimated that organic matter content in H horizon was as 10w as that in F horizon. 4)The ratio of fungal and bacterial biomass was lower in the laurel-leaved forest soil (BD-1) than that in the Cryptomeria japonica forest soils (BD-2, and Pw). So, we estimated that fungal biomass was relatively small in the laurel-leaved forest soil.