Ectomycorrhizae capable of degrading organic polymers proliferate in nitrogen(N)-limited, disturbed terrestrial ecosystems, which can supply host plants with organic N via fungal symbiosis. In estimating N transfer, N isotope can be a useful marker due to the isotopic fractionation between symbiotic partners. This study was carried out on Mt. Koma where the facilitative relation between Salix reinii and Larix kaempferi has taken an interest as the succession is going on. N status, N transfer, and role of mycorrhizae were evaluated on Mt. Koma where the 1929 eruption completely destroyed the former vegetation. With N and N isotope of tephra, non-mycorrhizal plant (Carex), ectomycorrhizal plants (Larix and Salix) and ectomycorrhizae, it was evident that Larix and Salix were taking advantage from mycorrhizal N-transfer and it also showed elevational and mycorrhiza-successional dependency. Although N-dependencies on mycorrhizae (f) of Salix were similar as 77%~80% at both 890 m and 650 m elevations, f values of Larix were 22% and 58% at high and middle elevations, respectively, which meant the succession of Larix-specific mycorrhizae went together with Larix and played an important role in N-transfer for Larix revegetation.