Long‐term fluctuations and mechanisms of seed production of riparian tree canopy species

Annual seedfall was measured over a 24-year period for three canopy species, Fraxinus platypoda, Pterocarya rhoifolia, and Cercidiphyllum japonicum, in riparian forest the Chichibu Mountains, central Japan. We collected seeds from 20 traps approximately every month, except winter. platypoda P. rhoifolia fluctuated, with 2-year cycle. The of C. japonicum also but this species produced year, an approximate 4-year simple moving average 5 years F. maintained at constant level period, it gradually increased japonicum. Each year's influenced by previous seedfall. results suggest that fluctuations amount were almost entirely dependent on stored resources, regardless weather. Conversely, resources temperature or precipitation summer year before flowering. These differences seed production patterns associated life history characteristics such as size regeneration mechanisms.