|| 要旨トップ | 目次 |||日本生態学会第62回全国大会 (2015年3月、鹿児島) 講演要旨
一般講演（ポスター発表） PA1-021 (Poster presentation)
To clarify the role of ectomycorrhizae (ECMs) on nitrogen (N) transfer to Larix kaempferi (larch) and Salix reinii (willow) in harsh ecosystems on the volcano Mount Koma, northern Japan, N status and pathways were evaluated by N isotopes. The tephra N content was higher at the higher elevations where willow was dominant and played as an important N source. The larch varied in N-dependencies on ECMs from 0 to 90% with decreasing elevations, changing to dominant species at lower elevations, while the willow cover decreased with decreasing elevations, accompanying gradual decrease in N-dependencies on ECMs from 80% to 25%. The larch also had lower isotopic signature, i.e., higher N-dependency on ECMs, in the early growing season than the late growing season, while willow did not show seasonal variations in isotopic signature. The larch compensated the decrease of N availability, caused by decrease of willow patch with decreasing elevations and varying seasonal N demand, with flexible and strong mycorrhizal symbiosis, while willow responded unfavorably to mycorrhizal relations with elevations. The differences in N dependencies of early and late colonizers on ECMs were likely to be related to the species replacement along a successional gradient.