| 要旨トップ | 目次 | | 日本生態学会第73回全国大会 (2026年3月、京都) 講演要旨 ESJ73 Abstract

一般講演（口頭発表） Q01-04 （Oral presentation）

#### Effects of enhanced seasonal precipitation on gas exchange of Pinus densiflora seedlings【E】

*Hee-eun YOON, Heejae JO, Jae-Ah LEE, Yowhan SON（Korea Univ.）

This study examined the effects of enhanced seasonal precipitation on gas exchange parameters of Pinus densiflora seedlings through a greenhouse experiment conducted in Seoul, South Korea. Four precipitation treatments were applied to one-year-old P. densiflora seedlings from April to October, 2025: control (C), 40% increase in spring and fall (PSF), 40% increase in summer (PSU), and 40% increase continuously from spring to fall (PC). Net photosynthesis (A), transpiration (E), and stomatal conductance (gs) were measured monthly using a portable photosynthesis system, and intrinsic water use efficiency (iWUE) was additionally calculated. For all four variables, significant interactions between treatment and measured month were detected. Monthly comparisons revealed that in May, A, E, and gs were higher under PC and PSF compared to C, while iWUE was lower under PC and PSF compared to C. Specifically, A was 12.8% and 20.5% higher under PC and PSF compared to C, respectively. This likely reflects that enhanced water availability during spring promoted stomatal opening and carbon assimilation. However, differences observed in May disappeared from June, and enhanced precipitation during summer and fall did not induce any significant differences among treatments. These results suggests that while enhanced precipitation initially promoted gas exchange during spring, likely due to this period being the most active growth phase, the effects did not persist in following seasons. This indicates that enhanced precipitation may not have a significant impact on gas exchange parameters of P. densiflora under a short-term experiment.

日本生態学会