Non-structural carbohydrates mediate seasonal water stress across Amazon forests

This is the final version. Available from Nature Research via the DOI in this record.The non-structural carbohydrates concentration data are available at www.forestplots.net/data-packages/Signori-Muller-et-al-2021 (https://doi.org/10.5521/forestplots.net/2021_3), all recorded species, genus and family names were checked and standardized using the Taxonomic Name Resolution Service (tnrs.biendata.org). The mean growth rate, potential tree size and mortality rate are available at www.forestplots.net/data-packages/coelho-de-souza-et-al-2016 (https://doi.org/10.5521/FORESTPLOTS.NET/2016_4). The climatic data are available at www.worldclim.org/data/index.html. Enhanced vegetation index data are available at www.zenodo.org/record/3159488#.YBW_u3f7Tlw (https://doi.org/10.5281/ZENODO.3159488). Leaf water potential data are available upon reasonable request to the correspondence author. Branch wood density data are from Tavares et al. (in prep) and Vasconcelos Barros (unpublished data). The inventory data for species selection are from the RAINFOR network available upon request at www.forestplots.net.Non-structural carbohydrates (NSC) are major substrates for plant metabolism and have been implicated in mediating drought-induced tree mortality. Despite their significance, NSC dynamics in tropical forests remain little studied. We present leaf and branch NSC data for 82 Amazon canopy tree species in six sites spanning a broad precipitation gradient. During the wet season, total NSC (NSCT) concentrations in both organs were remarkably similar across communities. However, NSCT and its soluble sugar (SS) and starch components varied much more across sites during the dry season. Notably, the proportion of leaf NSCT in the form of SS (SS:NSCT) increased greatly in the dry season in almost all species in the driest sites, implying an important role of SS in mediating water stress in these sites. This adjustment of leaf NSC balance was not observed in tree species less-adapted to water deficit, even under exceptionally dry conditions. Thus, leaf carbon metabolism may help to explain floristic sorting across water availability gradients in Amazonia and enable better prediction of forest responses to future climate change.Natural Environment Research Council (NERC)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior-BrasilBrazilian National Council for Scientific and Technological DevelopmentNatural Environment Research Council (NERC)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior-BrasilCoordenação de Aperfeiçoamento de Pessoal de Nível Superior-BrasilSão Paulo Research FoundationMINECO FUN2FUNDRESSU.S. Department of EnergyThe Royal SocietyEuropean Research Council (ERC)The Gordon and Betty Moore Foundatio