biostudies-literatureUnknown617(7959)Tavares JVTropical forests face increasing climate risk^1,2, yet our ability to predict their response to climate change is limited by poor understanding of their resistance to water stress. Although xylem embolism resistance thresholds (for example, [Formula: see text]₅₀) and hydraulic safety margins (for example, HSM₅₀) are important predictors of drought-induced mortality risk^3-5, little is known about how these vary across Earth's largest tropical forest. Here, we present a pan-Amazon, fully standardized hydraulic traits dataset and use it to assess regional variation in drought sensitivity and hydraulic trait ability to predict species distributions and long-term forest biomass accumulation. Parameters [Formula: see text]₅₀ and HSM<sub>50</sNature111-117https://www.ebi.ac.uk/biostudies/studies/S-EPMC10156596biostudies-literatureBasin-wide variation in tree hydraulic safety margins predicts the carbon balance of Amazon forests.PMC10156596Feldpausch TREsquivel-Muelbert AAragao LSignori-Muller CMencuccini MHuaraca Huasco WLola da Costa ACde Camargo PBGalbraith DRBittencourt PMarimon BHBrienen RRodrigues GGilpin MTalbot JCastro WMorandi PEspejo JSChama Moscoso VMonteagudo Mendoza ASilveira MCumapa ERMPerez Mullisaca FMMarimon BSDisney MOliveras Menor ITavares JVRuschel ARSchlickmann MGloor EHonorio EScalon MCMuscarella RAcosta MFernandes LPhillips OLLewis SCosio EGDiniz FCUgarteche MTMMartinez FAlmeida EAraujo-Murakami AChambers-Ostler ABaker TRBaca JVieira SASanchez JMBSalinas NFlores Llampazo GSantos JARSalas Yupayccana CAJancoski HDavila Cardozo NMalhi YBarros FVPenha Dda Costa Silva RTintaya JSRibeiro SCTello LOliveira RSHiguchi NHirota MFerreira LPereira LCoelho de Souza FVedovato LMarca Zevallos MJTeixeira RMeir PChino RSCGiacomin LFancourt MRowland LNina ACuellar GAVasquez RDel Aguila Pasquel JRocha MCda Cruz WJAfalseBasin-wide variation in tree hydraulic safety margins predicts the carbon balance of Amazon forests.Tropical forests face increasing climate risk^1,2, yet our ability to predict their response to climate change is limited by poor understanding of their resistance to water stress. Although xylem embolism resistance thresholds (for example, [Formula: see text]₅₀) and hydraulic safety margins (for example, HSM₅₀) are important predictors of drought-induced mortality risk^3-5, little is known about how these vary across Earth's largest tropical forest. Here, we present a pan-Amazon, fully standardized hydraulic traits dataset and use it to assess regional variation in drought sensitivity and hydraulic trait ability to predict species distributions and long-term forest biomass accumulation. Parameters [Formula: see text]₅₀ and HSM<sub>50</s2023-01-01T00:00:00Z2023 May2025-04-04T14:44:53.489Z2025-04-04T14:44:53.489ZS-EPMC101565963710090110.1038/s41586-023-05971-3