Factors affecting pollinator visitation and reproductive success in Sonneratia caseolaris and Aegiceras corniculatum in a mangrove forest in India

Pollinator visitation to, and tile reproductive success of, Sonneratia case olaris (Sonneratiaceae) and Aegiceras corniculatum (Myrsinaceae) was invest igated in a mangrove forest in India. S, caseolaris was shown to be primari ly outcrossed and A. corniculatum was shown to be a selfing species. The fl owers of both plant species attracted several diurnal and nocturnal visitor s. Earlier reports had indicated that S. caseolaris flowered for one night and was exclusively night-pollinated. But flowers of this species were foun d to be in bloom both at night and during the day, and diurnal visitors to the flowers were more diverse and frequent than nocturnal ones. This was re lated to tile higher volume and energy value of nectar in the morning. Tile effects of time of day and temperature on visitation rates were quantified . The importance of visitors to plant reproductive success was investigated via controlled visitor-exclusion experiments. Pollinators were expected to be more important for the outcrossing species than for the selfing species , and this was confirmed by the results of thr exclusion experiments. In S. caseolaris reproductive success was determined both by pollinator availabi lity and the intensity of flower and fruit predation, while in A. cornicula tum it is likely to be resource limited.