Effects of Differences in Forest Floor and Canopy Vegetation on Ectomycorrhizas of Betula platyphylla var.japonica: A Test Using Seedlings Planted into Soils Taken from Various Sites

Abstract

Effects of different forest floor vegetation types in secondary forest and of conversion to plantation on the quality and quantity of ectomycorrhizas are mostly unknown.Betula platyphylla var.japonica seedlings were used for bioassays of ectomycorrhizal fungal inoculum using soils from four 50-year-oldB. platyphylla var.japonica forests that had different types of forest floor vegetation: two with shrub types, one with aSasa type, and one with a grass type. Seedlings were also grown in soil from a nearby monospecific plantation ofChamaecyparis obtusa. Ectomycorrhizas formed 13 to 26% of root length of seedlings grown in soil from the five different sites. The maximum percentage of ectomycorrhizal formation was obtained from the grass-type forest. The dominant type of ectomycorrhiza in the two shrub-type forest soils was the same as that in theSasa-type forest soil. The dominant types of ectomycorrhizas in the grass-type forest soil and in theC. obtusa plantation soil were different from that in the two shrub-type forest soils and in theSasa-type forest soil. The results of this investigation suggest that the type of forest floor vegetation, accompanied with changes in thickness of the A0 horizon, might affect the ectomycorrhizal fungi in the soils ofB. platyphylla var.japonica forests. Establishment of artificial plantations ofC. obtusa might change the ectomycorrhizal fungi that could associate withB. platyphylla var.japonica seedlings in soil.