Differences in nitrogen redistribution between early and late plant colonizers through ectomycorrhizal fungi on the volcano Mount Koma

Abstract

Relationships involving the transfer of nitrogen (N) among Salix reinii (willow), Larix kaempferi (larch), and mycorrhizal fungi were investigated in a ridge and hillslope on the volcano Mount Koma in northern Japan using a two‐pool fungal model. This model estimated N transfer among the examined taxa by measuring changes in the stable isotope ratio of N (δ15N). Although N content in tephra was low at both sites, it was higher on the ridge than on the hillslope, and higher in the willow patch than on bare ground or in the larch understory. The non‐mycorrhizal sedge (Carex oxyandra) exhibited non‐significant differences between the two sites regarding δ15N for N obtained from tephra. Larches developed a relationship with larch‐specific Suillus mycorrhizal fungal species in the roots, and had a lower foliar δ15N on the hillslope than on the ridge. The larch δ15N increased during the growing season, while the willow δ15N remained stable. The dependence of larch on mycorrhizal fungi for N uptake was 3–5 % on the ridge and 56–76 % on the hillslope in autumn. Therefore, larches exhibited a flexible symbiotic relationship with mycorrhizal fungi for obtaining N. Over 45 % of the N taken up by willow plants was obtained from mycorrhizal fungi at both sites. In conclusion, willow plants promoted N deposition in tephra through the litter supply, and formed a stable relationship with mycorrhizal fungi. This enabled successful revegetation with larch plants, which exhibited flexibility in terms of N uptake (i.e., dependent on mycorrhizae or from tephra).

Role ofSalix reiniipatches in spatio-temporal patterns of cohabitants on a Japanese volcano

“…For example, an invasive tree, Larix kaempferi, establishes in the Salix reinii shrubs with different ways at different elevations on Mount Koma (Akasaka and Tsuyuzaki 2005). Larix kaempferi changes flexibly the pathways of nitrogen uptake directly form the volcanic deposits and indirectly from mycorrhizal fungi while S. reinii does not change the nitrogen dependence on them (Kwon and Tsuyuzaki 2016). Therefore, the effects of shrub patches on the cohabitants should be evaluated with different elevations (Schöb et al 2013).…”

Differences in C, N,δ13C, andδ15N among plant functional types after a wildfire in a black spruce forest, interior Alaska

“…Stable isotope analysis has various advantages in the quantification of C and N cycles, represented by  15 N and  13 C. Specifically,  13 C concentrations in leaves increases with increasing leaf-level intrinsic water use efficiency (WUE) in C3 plants (Dawson et al 2002) and  15 N concentrations are related to mycorrhizal associations and their related N dynamics (Kwon and Tsuyuzaki 2016). These patterns imply that measuring  13 C and  15 N could detect interactions between WUE, which is reduced by changes in moisture and temperature in the underground after intensive wildfire (Volik et al, 2021), and mycorrhizal associations in boreal forests (Hobbie and Hogberg 2012).…”