Agradecimentos: We are thankful to F. Elias for support in figure preparation. This project was funded by CAPES Science Without Borders grant 223211/2014 to IO. BHMJ and BSM were supported by the PELD/CNPq project (Transição Cerrado-Amazônia: bases ecológicas e socioambientais para a conservação , Proc. # 403725/2012-7 and 441244/2016-5). MCS was supported by a postdoctoral fellowship from CAPES Ver menos

Abstract: Leaf water potential is a good indicator of tree species responses to rainfall seasonality, allowing to better understand water stress effects on vegetation. We investigated daily and seasonal patterns on leaf water potentials of 21 dominant species in three distinct vegetation types from the Cerrado-Amazonia transition to assess how they respond to seasonal changes in water availability. We found that the variation on leaf water potential (?l) across species was higher in the dry compared to the rainy season, for all vegetation types. Typical cerrado and cerradão species showed similar patterns, with higher ?l regulation under higher VPD and lower variation in predawn ?l (??pd), indicating root access to soil water even during intense drought. In contrast, seasonal forest species showed lower regulation under lower VPD effects in both seasons, and higher ??pd, indicating lower access to deep water in the soil. These differences revealed two main groups of species: higher ?l regulators with a strategy isohydric occurring in both typical cerrado (savannah) and cerradão (woodland), and lower ?l regulators with anisohydric strategy, occurring in seasonal forest. Our results suggest that seasonal tropical forest species will become very vulnerable to predicted increases on drought severity in the region Ver menos