In the past decades, drought-induced forest die-off has been recorded on every forested biome, exerting great effects on biodiversity and ecosystem functions (Allen et al., 2010; Hartmann et al., 2018; Brodribb et al., 2020). A general understanding of forest vulnerability to damage due to climate is lacking, because of our limited understanding of the variation in lethal water potential (Ψlethal ) of trees. Achieving this critical goal requires a reliable proxy for Ψlethal that can be used to characterize many species in a forest community.