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Sympatric plant species exhibit various patterns in flowering phenology, from continuous to supra-annual and from periodic to intermittent pulses. This phenological variation is evident in many forests. Hypotheses propose that plant-animal interactions, such as pollination and seed predation, and ancestral signature may be responsible for differential patterns of flowering among sympatric species. In order to investigate the importance of these potential causes for diversification of flowering patterns among sympatric species, we characterize flowering periodicity and synchrony for 148 species with 18-year weekly flower data in the 50-ha Forest Dynamics Plot in Pasoh Forest Reserve, Malaysia. Periodicity is calculated with Fast Fourier Transform. Synchrony is determined by the proportion of flower produced within the flowering time of Shorea species, the renowned indicator species for the community level synchronous flowering. We then explore the relation of phenology pattern to dispersal mode and phylogeny. Our results showed that 105 species exhibit supra-annual flowering patterns and 84% of these species participated in GF events. We also found 60% of species flowered subannually and annually produced substantially more flowers during general flowering events. We found a significant relationship between seed dispersal mode and synchrony types implied the importance of seed predator satiation for intermittent flowering species. No clear relationship was found between flowering periodicity and seed dispersal type. We found no phylogenetic signals for flowering phenology, for both periodicity and synchrony. Regular flowering pattern in this aseasonal forest could not be explained by either causes tested here. The diversification of phenology patterns in aseasonal tropical forests calls for further investigation.

Keywords:

flowering phenology, synchrony, dipterocarp, seed dispersal, phylogeny

Yu-Yun Chen, I-Fang Sun, Matteo Detto, Stephen Hubbell, Tze Leong Yao, S Joseph Wright

Presentation within symposium:

S-16 Long-term climate effects on interannual variation in tropical forest reproduction: a global perspective

Flowering phenology in a lowland mixed dipterocarp forest

-Review-