The importance of wood density in determining the phenology of tree species in a coastal rain forest

The phenology of tree species in tropical dry forests is related to a well‐characterized interaction between functional traits (e.g., wood density) and climatic seasonality (e.g., drought stress), but the existence of these relationships in tropical wet forests is largely unknown. For 12 months, we monitored the vegetative and reproductive phases of 281 individuals of 46 tree species in a coastal rain forest in Northeastern Brazil. We hypothesized that wood density and related tissue water storage would reliably distinguish phenological groups of trees, and that leaf shedding, flushing, and flowering in high wood density species would be closely related to rainfall, due to low tissue water storage capacity in these species. By contrast, we predicted leaf unfolding and flowering of low wood density species would depend exclusively on photoperiod. As predicted, wood density and saturated water content were inversely correlated, and species with either high or low wood density had distinct phenological patterns and levels of synchrony within species. Abiotic variables were not strongly associated with phenological events. Phenophases of leaf unfolding, flowering, and fruiting occurred earlier in low wood density species than in high wood density species, possibly indicating an adaptive strategy for preemptive resource capture. Abstract in Portuguese is available with online material.