Quantities and types of ectomycorrhizal and endophytic fungi associated with Betula platyphylla var. japonica seedlings during the initial stage of establishment of vegetation after disturbance

Ectomycorrhizal and endophytic fungi of Betula platyphylla Sukatchev var. j aponica Hara seedlings were investigated by bioassay using soils from sites where the surface layer had been removed by destructive disturbances. Soil samples were taken from sites A, B, C and D, where 1, 2-3, 4-5, and 7-8 ye ars, respectively had passed since disturbance. Naturally regenerated B. pl atyphylla var. japonica seedlings grew at sites C and D, but not at sites A or B. The percentages of ectomycorrhizal formation in seedlings were signi ficantly lower in the soils from site A (4%) and site B (13%), compared to those in the soils from site C (53%) and site D (37%). The numbers of ectom ycorrhizal morphologic types in sites A, B, C, and D were eight, five, one, and seven, respectively. The same dominant type of ectomycorrhiza was foun d in sites C and D, and this type was different from those in sites A and B . The frequencies of colonization of seedling roots by endophytic fungi, es pecially Mycelium radicis atrovirens Melin (MRA) in soils from sites A and B were 31 and 33%, respectively; these frequencies were significantly highe r than those for site C (0%) and site D (2%). During the initial stage of e stablishment of vegetation following disturbance, the quantities and types of ectomycorrhizal fungi in the field that have the potential to associate with B. platyphylla var. japonica might rapidly change after invasion of th e host plant. Ectomycorrhizal fungi seemed to compete with endophytic MRA f ungi for colonization of the roots of B. platyphylla var. japonica seedling s.