Interspecific variation in leaf phenology and its relationship with plant traits in a seasonal tropical forest

Abstract Leaf phenology plays an important role in plant life‐history strategies and in determining ecosystem‐level fluxes of carbon and water. In seasonal tropical forests, leaf phenology is highly variable among tree species, but limited quantitative data have hindered our understanding of leaf phenology and its relationship with other plant traits. We investigated leaf phenology and its relationship to plant traits in 48 tree species in a seasonally dry tropical forest. Our study combined image time series acquired by uncrewed aerial vehicles (UAVs) with ground‐based forest inventories and plant functional and life‐history traits. Quantitative metrics of phenology revealed wide variation along two dimensions –the degree and timing of deciduousness—with large interspecific variation. We categorized each species to one of three phenological groups: evergreen (25 species, leaf cover always >60%), early deciduous (six species) and late deciduous (17 species). Early‐deciduous species were deciduous near the beginning of the dry season and for a relatively short period (mean 22 days); late deciduous species were deciduous later in the dry season and for a longer period (mean 63 days). In multiple regression models, plant traits explained roughly 50% of the interspecific variation in phenology metrics. The best predictors in these models were xylem vessel area (species with larger vessels tended to have earlier start dates of deciduousness), LMA (negative relationship with the degree of deciduousness) and leaf phosphorus content (positive relationship with the degree of deciduousness). Synthesis . Co‐occurring tree species in a seasonal tropical forest vary widely in the degree and timing of deciduousness, with natural breaks in this variation defining three phenological groups—evergreen, early deciduous and late deciduous—and continuous variation in phenological traits within the deciduous groups. Interspecific variation in the degree and timing of deciduousness is associated with other plant traits. Combining UAV imagery with ground‐based forest inventory and trait data can lead to improved understanding of the complex phenology of tropical forests, which is crucial for accurately predicting carbon and water fluxes under changing climates. Read the free Plain Language Summary for this article on the Journal blog.