1999 年 49 巻 1 号 p. 21-35
Although various leaf traits (such as photosynthetic capacity, leaf mass per area (LMA), longevity, nitrogen content and toughness) are highly influenced by changes in environmental conditions, strong correlations exist among leaf traits. Photosynthetic productivity and leaf persistence are negatively correlated, i.e., short-lived leaves often have higher photosynthetic activity and lower defensive ability than long-lived leaves. There are two major hypotheses for explaining the observed variation of leaf longevity: the nutrient use efficiency theory and the carbon balance theory. The theories differ in their viewpoints of the factors limiting photosynthetic activity, i.e. mineral limitation and carbon limitation. In general, plants living in tundra environments suffer from a short growing season, and the extent of this stress changes along the altitudinal, latitudinal and snowmelt gradients in arctic and alpine ecosystems. As season length decreases, deciduous plants produce shorter-lived, lower-LMA and nitrogen-richer leaves, whereas evergreen plants produce longer-lived leaves within and among specics. This contrasting pattern of changes in leaf traits can be explained by a simple graphic model based on the carbon balance theory. The ecological significance of leaf-trait variations should be applied to the fields of reproductive ecology and biological interactions between plants and herbivores.