Effects of the Length of the Snow-Free Period on Leaf Longevity in Alpine Shrubs: A Cost-Benefit Model

Leaf longevities of three woody dwarf-shrub species were investigated in relation to the length of the snow-free period in a mountain area in Hokkaido, northern Japan. Leaf longevity of a deciduous species, Sieversia pentapetala, slightly increased with increasing length of the snow free period. In contrast, the leaf life-span of two evergreen species, Phyllodoce aleutica and Rhododendron aureum, decreased with increasing snow-free period. These trends are consistent with a cost-benefit model for leaf longevity as a function of the changing length of the yearly period favorable for photosynthesis. Hence the plastic changes in leaf longevity with varying snow-free periods were concluded to be adaptive traits for maximizing photosynthetic gain for the plants