Timing of Sprouting in Hamabiwa (Litsea japonica Juss.) Growing in a Coastal Dwarf Forest

Abstract

Morphology, age structure and growth of sprouts in Hamabiwa (Litsea jufionica Juss.) growing in a coastal dwarf forest in northern Kyushu were investigated, and timing of sprouting was discussed in relation to activities of terminal buds. Sprouts of Hamabiwa were collected and n~orphology of sprouts and their prilnordia were observed. On the stem surfaces of Hamabiwa, there were numerous suppressed buds with vascular traces connected to the pith. Similar vascular traces were observed at the base of sprouting positions. So, the priinordia of sprouts in Hamabiwa were assumed to be suppressed buds. 67 sprouts from six clumps were randomly sampled for age structure analysis, Although there were large fluctuations in the frequency distributioil of sprout age, sprouts existed in most age classes. The frequency distribution showed a gentle inverse-J shape indicating a high survival rate of sprouts. Disks of stems of one clump with 7 sprouts were sampled for stem growth and sprouting analysis. Sprouting was observed in years when the height growth rate declined or in the following years. This result suggested that sprouting was closely related to the activity of terminal buds. However, there was no significant relationship between sprouting and volume or radial growth rates. From these results, it was suggested that Hamabiwa growing in a coastal dwarf forest flushes sprouts constailtly due to stress at terminal buds, and maintains their