Effect of snow-free duration on leaf life-span of four alpine plant species
Leaf life-spans and specific leaf weights of four plant species, Phyllodoce aleutica, Rhododendron aureum, Sieversia pentapetala, and Potentilla matsumurae were compared along a gradient of decreasing snow-free duration in alpine snow beds. Life-span was obtained by observation from emergence to senescence for deciduous plants and was estimated from leaf age distributions for evergreen plants. Along the gradient, the evergreen shrubs Ph. aleutica and R. aureum had extended leaf life-spans, whereas the deciduous shrubs S. pentapetala and the deciduous herb Po. matsumurae had reduced leaf life-spans. Specific leaf weights, obtained by dry weight per unit leaf area, increased in Ph. aleutica but decreased in S. pentapetala and Po. matsumurae along the gradient. These phenomena are considered adaptive adjustments for maintaining a positive carbon balance under the conditions of limited photosynthetic season. Key words: alpine snow bed, carbon balance, deciduous plants, evergreen plants, leaf life-span, specific leaf weight.