Between campo rupestre and rainforest: evidence of conservative evergreen strategies in contrasting tropical environments

Tropical plants continuously or seasonally shed leaves in a complex dynamic that remains not fully understood. Leaf phenology has received limited attention compared to reproductive phenology, especially in humid environments where water balance remains positive year-round and most species are considered evergreen. Recent studies suggest that even in such environments, leaf turnover may respond to environmental drivers. In this context, the present study sought to analyze the vegetative phenology of 14 species of Myrtaceae in gallery forests adjacent to the Lençóis River, in the Municipality of Lençóis, and in campo rupestre vegetation on the Mãe Inácia Mountain, in the Municipality of Palmeiras, Chapada Diamantina, Brazil. Phenological observations were undertaken on a monthly basis on 141 marked individuals (5-10 individuals per population) for two years. During the observation period, the intensity of leaf fall and leaf flush (buds and young leaves) were estimated. The species were classified as perennial (with reduced leaf loss, without concentrated loss), episodically perennial (with concentrated leaf fall) and semideciduous (leaf production and loss well marked). These results suggest that, despite environmental differences, Myrtaceae species exhibit conservative vegetative strategies, shaped by both functional adaptations and evolutionary constraints. Understanding these patterns contributes to a broader comprehension of plant responses to seasonal environments and underscores the importance of vegetative phenology in ecological and evolutionary studies of tropical flora.