Autecology of Successional Dominants of the Cool-temperate Forest in Japan : On Sapling Stage of Fagus crenata Blume

Saplings of Fagus crenata, whose averaged height and weight and weight were 124.1 cm and 237.3 g were grown at an experimental field located in the montane region of central Japan. The saplings initiated the leaf unfolding in mid May and shed the leaves in late October (about 150 leaf days) in 1989. The mean net increment of the plant was 156.6 g during the growing season. The current shoots and leaves were formed from the reserve matter produced and stored in the branches and trunk during previous year. The relationship between weight masses of above・ (T : g) and below (R : g) ground was described as : R = 0.77T1.18 The relationship between weight masses of leaves (Wl : g) and trunk and branches (Wib : g) is given as : Wtb=3.75Wl1.07 The weight ratio of leaves to whole plant was about 12% through the growing season. The plant absorbed 910 mg of nitrogen from the soil during April to September. The nitrogen was first allocated to leaves and re-allocated from the leaves to the branches and trunk at shedding. The weight ratio of plant net increment to total nitrogen absorbed from soil was 172.1. By combining these ecological characteristics, Fagus crenata appeared to be dominant in the climax forest. Key words : Fagus crenata, allometry, nitrogen allocation, T/R rati