PARENT SESSION
Poster Session 6: Arctic and Alpine Ecology
Tuesday, August 9, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Morphological, phenological and ecophysiological characteristics of young and mature plants of Polygonum weyrichii at an alpine timberline of Mt.Fuji.

NAKANO, Takashi^*,1, MITAMURA, Masako², MARUTA, Emiko², ¹ Yamanashi Institute of Environmental Sciences, Fuji-Yoshida, Yamanashi² Toho University, Funabashi, Chiba

ABSTRACT- In upper timberline of Mt. Fuji, basaltic scoria desert spreads in a great extent. Polygonum weyrichii is well known as a pioneer species around alpine timberlines of Mt. Fuji. In this study, we compare phenological, morphological and physiological (photosynthesis and water relation) characteristics of young and mature plants of P. weyrichii, to reveal the manner of plant adaptation to environment as a species. We choice adult plants (having more than ten shoots and 30cm in height) and young plants (having one shoot and less than 10cm in height). Growing season of young plant was one month longer than that in adult plant. The leaf weight ratio (LWR) of young plant was higher than that in adult plant. Adult plant had about two times higher maximum net photosynthetic rate (P_n) and leaf water vapor conductance (g_leaf) in the field than that in young plant. Initial slope of Ci-A curve and P_n in CO₂ saturation were also about two times higher in adult plant than that in young plant. Leaf nitrogen content was significantly higher in adult plant. The minimum leaf water potential in the field was not differed between adult and young plant, however leaf water potential at turgor loss point obtained from PV analysis was less negative in young plant than that in adult plant. These results indicate that young plant, having lower g_leaf and lower photosynthetic capacity, has longer growing season and higher LWR. Longer leaf longevity and higher LWR of young plants are important for matter preduction. On the other hand, higher g_leaf and higher P_n of adult plants are important for matter preduction.

Key words: alpine, age, adaptaion, ecophysiology