Reproductive phenology of a tropical canopy tree, Spondias mombin

We studied the reproductive phenology of isolated populations of Spondias m ombin to determine the degree of flowering and fruiting synchrony among pop ulations and to examine spacial and temporal variability in fruit productio n. The study was conducted on six small islands (1.8-3.5 ha) in the Panama Canal. All individuals (10 cm in diameter at breast height (DBH) were marke d in 1991 and censused each year through 1994 to record recruits and deaths . All marked trees were censused monthly for flowering and fruiting activit y from April 1992 through December 1995. Spondias mombin was seasonal and h ighly synchronous in flower and fruit production among islands and across y ears. Proportions of individuals fruiting varied among islands, years, and tree size classes. There was a positive relationship between probability of fruit production and tree size. Synchronous reproductive activity in S. mo mbin probably was due to responses to proximate environmental cues such as fluctuations in irradiance, but other factors must have been responsible fo r temporal and spatial variation in reproductive performance. We suggest th at this variation may have been due partly to temporal and spatial differen ces in pollinator abundance.