Long-term Changes in Fruit Phenology in a West African Lowland Tropical Rain Forest are Not Explained by Rainfall

Decreases in rainfall have been proposed to have a negative impact on tropical rain forests, and West Africa is currently experiencing a decline in rainfall at the multi-decadal scale. Here, we present analyses of a long-term dataset on the plant fruiting status from individuals of 44 species of the tropical rain forest of Tai National Park, Cote d'Ivoire. This study includes records of 1401 individuals collected at monthly intervals for over 12yr, 984 of which survived throughout the entire study period. The aims of this study were to: (1) quantitate inter-annual trends in species and forest scale fruit presence; and (2) test the importance of rainfall in explaining inter-annual fruit presence variability. Long-term upward trends in the expected proportion of individuals with fruits were found for the majority of species, while no significant downward trends were detected, driving a significant upward trend at the community level. Peak production months of the upward trending species were not associated with the dry or wet season. Significant rainfall correlations with the total proportion of individuals showing fruit were generally negative, with only five species showing significant positive correlations. Taken together, these results suggest that the observed inter-annual trends and variability of fruit abundance are currently not associated with rainfall. We discuss several parsimonious and complex alternative explanations.