Divergent carbohydrate-use strategies in woody species in a tropical dry forest

Abstract Producing and storing non-structural carbohydrates (NSC) during the short rainy season in a tropical dry forest (TDF) may determine the survival of woody species. As rainy seasons become increasingly irregular under global climate change, advancing our understanding of these dynamics is crucial for discussing the performance of woody species. In this study, we investigated two woody species widely found in the Brazilian tropical dry forest (Caatinga), Pityrocarpa moniliformis and Cenostigma microphyllum , focusing on the seasonal dynamics of NSC in leaves, stems, and roots, as well as the water status of adult plants under semi-arid climate conditions. We measured soluble sugars, starch, xylem water potential, and stomatal conductance across climatic seasons and their transitions. Both species decreased stomatal conductance during the transition from the rainy to the dry season. We observed that P. moniliformis reduced starch reserves and increased soluble sugar concentrations during this transition, while maintaining a higher water status compared to C. microphyllum . In contrast, C. microphyllum maintained relatively stable NSC concentrations across the evaluated periods. Our results suggest that the response of woody species is species-specific and does not always involve the preservation of carbohydrate reserves, as these species may tolerate low xylem water potential during the dry season. Furthermore, although both species are highly abundant in the Caatinga, their strategies of NSC dynamics among plant organs are divergent. The ecophysiological significance of these contrasting carbon allocation patterns is discussed.