Abstract
The leaf phenology of over-and understory trees was investigated in a deciduous broad-leaved forest in 1997. In the study area, the snow usually melts in late March or early April, and it does not prevent understory plants from using the light penetrated from the canopy. In the understory, the earliest leaf flushing was observed for Euonymus oxyphyllus and Prunus apetala in May, when the overstory trees were leafless. In the overstory, the earliest leaf flush was observed in late May for Betula platyphylla var. japonica and Prunus grayana. The latest was in early June for Castanea crenata. The leaf flushes of most of understory trees occurred earlier than overstory trees. Moreover, there is a tendency that smaller sized individuals wihin a tree species flush leaves earlier than those of large sized ones. Most of trees shed leaves in a short period at late October. From these, it is suggested that most of understory trees can utilize the favorable light in spring for photosynthetic activities before the leaf flushing of overstory trees.
