Figure 4.
Relationships among leaf morphology, leaf physiology and leaf lifespan in overwintering oaks in this study and in the GLOPNET dataset. (a) Bivariate relationships (log10 transformed) between the light-saturated photosynthetic rates based on leaf dry mass (Am, nmol g−1 s−1) and based on leaf nitrogen (PNUE, μmol mol−1 s−1), the leaf nitrogen content based on leaf dry mass (Nm, %), the leaf dry mass per area (LMA, g m−2), and the leaf lifespan (LLS, month) in the GLOPNET dataset. The light-blue filled circles and light-green open circles show data for evergreen and deciduous broad-leaves species in temperate forests in the GLOPNET dataset, respectively. The grey circles show other data in the dataset. Solid and dashed lines represent regressions with p < 0.05 and p ≥ 0.05 among evergreen oak species in this study, respectively. (b,c) Diagrams of correlations between the major parameters in the GLOPNET dataset (b) and overwintering evergreen oaks in Japan (c). The black and red arrows represent positive and negative correlations, respectively. The solid and dashed arrows represent strong and weak correlations, respectively. The correlations of Am, PNUE and LMA with Nm for the GLOPNET dataset are markedly different from those for the overwintering evergreen oaks in Japan, as shown by bold arrows in panel (c).