Fruiting phenology uncoupled from seasonal soil nitrogen supply in masting Fagus crenata trees.

Han, Qingmin; Kabeya, Daisuke; Inagaki, Yoshiyuki; Noguchi, Kyotaro; Fujii, Kazumichi; Satake, Akiko

Background and aims: Masting is a widespread reproductive strategy in perennial plants. Its mechanism remains largely uncertain, although it is generally accepted that internal nutrient dynamics play a role. We aimed to examine whether soil nitrogen (N) supply influences plant N acquisition and drives masting. Methods: We measured spatio-temporal variations in soil N mineralization rate and plant N uptake by roots using plant root simulator probes on the periphery of six fruiting and four non-fruiting trees in a mature Fagus crenata Blume forest. In parallel, N concentrations and biomass growth in leaves, current-year branches, cupules, nuts and winter buds were analysed for the same trees. Results: Soil N mineralization rates exhibited significant seasonal variations in both nitrate- and ammonium-N, and varied spatially up to 38-fold between spots sampled on the same date and 39-fold for the same tree in a growing season. Fruiting did not enhance N uptake by roots, and a dramatic decrease in soil N mineralization rate was observed in autumn during nut ripening. Translocation from cupules supplemented this N shortfall in mature nuts. Consequently, the amount of N amount per whole shoot, but not in ripe nuts per shoot, was correlated with the cumulative soil inorganic N. Conclusion: Masting is influenced ultimately by internal resource dynamics, which are decoupled from soil N dynamics. This may be a result of evolutionary selection to insulate trees from the high variation in local soil nutrients to ensure reproductive success.

LIFE sciences; BOTANY; SOIL dynamics; PLANT ecology; NITROGEN in soils

Plant & Soil, 2025, Vol 509, Issue 1, p237

0032-079X

Academic Journal

10.1007/s11104-024-06859-5