Assessing vertical seed dispersal through seed oxygen isotope ratios of Japanese larch ( <i>Larix kaempferi</i> )

Abstract Vertical seed dispersal, involving seed movement to higher or lower elevations, plays a vital role in plant adaptation to rising temperatures. However, its assessment has been limited owing to labor‐intensive processes. A recently developed method exploits the negative correlation between elevation and seed oxygen isotope ratios ( 18 O/ 16 O; hereafter δ 18 O) for efficient evaluation of vertical seed dispersal. Nevertheless, it remains unclear whether this method is suitable for conifers and whether plant size and age introduce noise into δ 18 O values, which would affect vertical seed dispersal estimations. In this study, we investigated the association between elevation and seed δ 18 O values of Japanese larch ( Larix kaempferi ) and explored the relationship among these oxygen isotope ratios, tree height, diameter at breast height (DBH), and age. Notably, we found a negative correlation between elevation and seed δ 18 O values of L. kaempferi but failed to detect any influence of tree height, DBH, and age on these oxygen isotope ratios. These findings suggest this method's potential for accurately estimating vertical seed dispersal across diverse plant lineages.