EFFECT OF SNOW-FREE DURATION ON LEAF LIFE-SPAN OF 4 ALPINE PLANT-SPECIES

Leaf life-spans and specific leaf weights of four plant species, Pyllodoce aleutica, Rhododendron aureum, Sieversia pentapetala, and Potentilla matsumurae were compared along a gradient of decreasing snow-five 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.