Annual periodicity of fruiting in temperate forests in Yakushima, Japan

Abstract

Fruiting phenology, assessed by seed fall, in five warm- and cool-temperate forests on Yakushima Island, southern Japan, was studied for two years in one 50 m × 50 m plot and for four years in four 100 m × 50 m plots. The elevation of the plots ranged between 170 and 1200 m a.s.l. Seed fall phenology showed annual periodicity in all five plots. This was clear when assessed by the number of species but became less clear when assessed by the biomass of seed litter. Community-level annual periodicity was based on the prevalence of population-level annual periodicity and interspecific synchronization of the fruiting peak from autumn to winter. Fleshy fruits had peaks of seed fall in a wider range of months than non-fleshy fruits, since it is sometimes beneficial to bear fruit outside the community-level fruiting peaks in order to avoid interspecific competition for animal seed dispersers. No consistent effect of climatic factors on seed fall phenology was detected.