Discerning photosynthetic seasonality in tropical forests is fundamental to both basic ecology (plant strategies for resource acquisition when resources are limiting) and the need to understand vegetation responses and feedbacks to a changing climate. The seasonality question provides an important threshold test to advance predictions of tropical forest response to future climate changes. Despite its importance, spatial and temporal photosynthesis patterns in tropical forests are highly uncertain and remain controversial as ecosystem models yield divergent results while satellite-based observations are subject to various artifacts associated with cloud leakage, aerosols, and sensor-sun observation geometries. In this research, in situ seasonal tower carbon flux and leaf-scale phenology measures from cameras were combined with satellite data to investigate the roles of climate drivers and biologic processes (leaf phenology and demography traits) on vegetation canopy photosynthesis. Our results show the importance of phenology traits on controls on seasonal photosynthesis.