Demography and growth pattern of understory shrubs in a Japanese beech forest.

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(1) In each year between 1995 and 1997, fruits production and its spatial destribution were studied for four shrub species in a Japanese beech forest. The amount of fruit production in the mast year, which were far less than those of tree species, were rather similar among three shrub species. The seed size and its morphology were also similar among them.(2) In all of four species sxamined, the mortality of stems rapidly decreased with the increase of ramet size but slightly increased again after the ramet reaching the flowering and seeding size. The pattern observed is the same with those reported for tree species which rarely sprout.Every year, 10-20% of the total number of stems were recruited by sprouting for four shrub species. The mortality of these sprouted stems in the first year was very low, about 10%.Every year, the current-year seedlings appeared for three species (Lindera umbellata var.membranacea, Magnolia salicifolia and Viburnum furcatum) in the forest floor, although its distribution were scattered and the densties were quite low.Clone morphology and the interconnection among stems were examined by excavating the clone. Vegetative reproduction by the fragmentation of layred branches was observed for Hydrangea panniculata.