Effects of vegetation change and soil disturbance on ectomycorrhizas ofBetula platyphylla var.japonica: A test using seedlings planted in soils taken from various sites

The occurrence and character of different types of ectomycorrhizas of birch seedlings were investigated in soils from three naturally regenerating birch stands: a forest site, a clear-cut site, and a site recently disturbed by plowing. Birch grown in soil from an evergreen broad-leaved forest without birch was also studied. The rate of ectomycorrhizal formation in the soil from the evergreen broad-leaved forest was lower than that in the soil from the other three sites. The ectomycorrhizal formation of seedlings grown in soil from the clear-cut and plowed sites were the same as or higher than that in soil from the birch forest site. The largest number of ectomycorrhizal types were formed in soil from the birch forest site. In the soil from the plowed site, only one type of ectomycorrhiza was formed, and it was different from the dominant type formed in soils from the birch forest site and the clear-cut site. The results of this investigation showed that equal levels of ectomycorrhizas were formed in soils from the different birch stands, but the types formed were different among those sites. It is likely that the different ectomycorrhizal fungi were better adapted to the soil conditions at each of those sites.