Seasonal and long-term patterns of reproductive phenology in the Wet Tropics rainforests of Australia

Understanding reproductive phenology in tropical rainforests is important for predicting forest dynamics, ecosystem processes, and forest vulnerability. Long-term plant phenology datasets from tropical rainforests are relatively rare, particularly in Oceania. Here, canopy observations collected by a single observer using a forest gondola system generated a 15-year weekly flowering and fruiting dataset of 132 species in the Wet Tropics of Queensland, Australia. Using this dataset, we investigated seasonal and long-term reproductive phenology at the community and species level. At the community level, flowering was strongly seasonal and concentrated in the wet season, while fruiting showed weaker seasonality and was generally concentrated in the dry season. The timing of peak flowering and fruiting activity differed between abiotic and biotic groups. Over the 15-year study period, some species advanced or delayed flowering and fruiting. Flowering timing was largely stable across both biotically and abiotically dispersed species, with most species showing no significant change. Changes in fruiting timing were more common among biotically dispersed species, including both advances and delays, whereas most abiotically dispersed species showed no significant change. Annual cycles were most common in flowering, whereas supra-annual cycles were predominant in fruiting. At the species level, reproductive activity occurred throughout the year but varied markedly in timing, with many species displaying supra-annual flowering and fruiting. Supra-annual flowering was more likely in biotically dispersed species, while supra-annual fruiting was more likely in species with larger seeds. Finally, we present the first comprehensive phenological calendar for 81 tree species in the Wet Tropics rainforests of Queensland. These findings provide a foundation for future ecological research and restoration practice in the region.