title: Seasonal change in light partitioning among coexisting species of different functional groups along elevation gradient in subalpine moorlands.
abstract: Species niches are expected to differ between different functional groups and between species with different functional traits. However, it is still unclear how functional traits contribute to niche separation between species coexisting in a community and between sites along environmental gradients. We studied seasonal changes in light partitioning among coexisting species belonging to different functional groups in moorland plant communities at different altitudes. We estimated the lifetime light absorption per unit invested leaf biomass (ΦLleafmass) as a measure of the benefit/cost ratio of light acquisition. Evergreen species absorbed more light in spring, whereas deciduous species absorbed more light in summer. A similar tradeoff was also found between short and tall species within each functional group. As a result, evergreen and shorter species had comparable ΦLleafmass values to those of deciduous and taller species. Evergreen species had higher ΦLleafmass at higher altitudes relative to deciduous species, suggesting that evergreen habit is more advantageous for the lifetime light interception at higher altitudes. Our results demonstrate that phenological tradeoffs for light partitioning can contribute to the coexistence of species with different functional traits. Our results also reveal that the most advantageous traits differ depending on environment.
authors.affiliation: Graduate School of Life Sciences, Tohoku University, Aoba, Sendai, 980-8578, Japan; Risk Analysis Research Center, The Institute of Statistical Mathematics, Tachikawa, Tokyo, 190-8562, Japan.
authors.forename: Chiho
authors.initials: C
authors.lastname: Kamiyama
authors.forename: Shimpei
authors.initials: S
authors.lastname: Oikawa
authors.forename: Kouki
authors.initials: K
authors.lastname: Hikosaka
mesh_terms: D000531:Altitude; D017753:Ecosystem; D007564:Japan; D008027:Light; D008954:Models, Biological; D018515:Plant Leaves / Q000502:physiology*; D018521:Plant Physiological Phenomena; D019655:Quantitative Trait, Heritable; D012621:Seasons
keywords: coexistence; deciduous; evergreen; functional trait; leaf life span; light acquisition; plant height; specific leaf area