title: Overwintering evergreen oaks reverse typical relationships between leaf traits in a species spectrum.
abstract: The leaf economics spectrum has given us a fundamental understanding of the species variations in leaf variables. Across plant species, tight correlations among leaf mass per area (LMA), mass-based nitrogen (N m) and photosynthetic rate (A m) and leaf lifespan have been well known as trade-offs in leaf carbon economy. However, the regional or biome-level correlations may not be necessary to correspond with the global-scale analysis. Here, we show that almost all leaf variables in overwintering evergreen oaks in Japan were relatively well included within the evergreen-broadleaved trees in worldwide temperate forests, but N m was more consistent with that in deciduous broadleaved trees. Contrary to the universal correlations, the correlation between A m and N m among the evergreen oaks was negative and the correlation between A m and LMA disappeared. The unique performance was due to specific nitrogen allocation within leaves, i.e. the evergreen oaks with later leaf maturation had lower N m but higher nitrogen allocation to photosynthetic enzymes within leaves, to enhance carbon gain against the delayed leaf maturation and the shortened photosynthetic period due to cold winters. Our data demonstrate that correlations between leaf variables in a local scale are occasionally different from averaged global-scale datasets, because of the constraints in each biome.
authors: Hokkaido Research Center , Forestry and Forest Products Research Institute , Hitsuji-gaoka, Toyohira-Ku, Sapporo, Hokkaido 062-8516 , Japan.
authors: Hisanori
authors: H
authors: Harayama
authors: Center for Ecological Research , Kyoto University , Hirano, Otsu, Shiga 520-2113 , Japan.
authors: Atsushi
authors: A
authors: Ishida
authors: Graduate School of Science and Technology and Department of Mathematical and Systems Engineering, Shizuoka University, Johoku, Naka-Ku, Hamamatsu, Shizuoka 432-8561, Japan; Department of Environmental and Forest Biology, State University of New York College of Environmental Science and Forestry, Syracuse, NY 13210, USA; Marine Biosystems Research Center, Chiba University, Kamogawa, Chiba 299-5502, Japan.
authors: Jin
authors: 0000-0003-1610-1386
authors: J
authors: Yoshimura
keywords: Quercus; leaf economics spectrum; leaf nitrogen; photosynthesis; winter cold