XVI International Botanical Congess

260 litter traps were used to monitor fruit production for 138 species for 10 years on Barro Colorado Island (BCI), Panamá. Production was greatest during the 1992 El Niño and lowest one year later after the mild 1993 dry season. Fruit production was again extraordinarily high during the 1997 El Niño. I hypothesize that (1) El Niño conditions enhance fruit production, (2) high fruit production consumes stored reserves limiting the next reproductive event, and (3) mild dry seasons reduce fruit production. Each plant species may respond to any combination of the three components of this hypothesis. Community-level production is extremely low when species sensitive to components 1 and 2 are entrained with species sensitive to component 3, or when a mild dry season follows one year after an El Niño event. El Niño events bring dry, sunny conditions to BCI and to a large portion of the wet tropics. Drought and sun may both favor fruit production in wet tropical forests. Drought is known to synchronize flowering, and sunny conditions may relieve light limitation.