Functional traits determine the vegetative phenology of woody species in riparian forest in semi-arid Brazil

Relationships between phenological and morphophysiological traits of functional groups of woody species in riparian forests of semi-arid environments are little understood, especially regarding the representativeness of these groups in the community. This study aimed to evaluate the influence of the leaf and wood morphofunctional characteristics on the vegetative phenology of woody species in a riparian forest in the Brazilian semi-arid region and how these traits act in the distribution of species in functional groups. Vegetative phenology and leaf traits (specific leaf area, leaf area, leaf thickness, and leaf dry matter content), wood density, and amount of saturated water in the stem and their association with soil water availability, relative air humidity, precipitation, temperature, photoperiod, and vapor pressure deficit were evaluated. Cluster analysis showed three functional groups ( n = 23): deciduous low wood density species (9%), deciduous high wood density species (48%), and non-deciduous species, which included semideciduous (17%) and evergreen species (26%). Deciduousness was positively related to specific leaf area and negatively related to leaf dry matter and leaf area. Deciduous and semideciduous species (55.1% and 7.5% of the individuals in the community, respectively) showed a strong dependence on abiotic factors linked to precipitation and temperature, while the evergreen species showed a strong dependence on the vapor pressure deficit to trigger their phenophases. We concluded that the studied functional traits act on the leaf habit, which is essential to understand how the phenology is projected within functional groups.