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@Article{BrumVIASAPDABBPO:2019:HyNiSe,
               author = "Brum, Mauro and Valdeboncoeur, Matthew A. and Ivanov, Valeriy and 
                         Asbjornsen, Heidi and Saleska, Scott and Alves, Luciana F. and 
                         Penha, Deliane and Dias, Jadson D. and Arag{\~a}o, Luiz Eduardo 
                         Oliveira e Cruz de and Barros, Fernanda and Bittencourt, Paulo and 
                         Pereira, Luciano and Oliveira, Rafael S.",
          affiliation = "{Universidade Estadual de Campinas (UNICAMP)} and {University of 
                         New Hampshire} and {University of Michigan} and {University of New 
                         Hampshire} and {University of Arizona} and {University of 
                         California} and {Universidade Federal do Oeste do Par{\'a} 
                         (UFOPA)} and {Universidade de S{\~a}o Paulo (USP)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Universidade Estadual 
                         de Campinas (UNICAMP)} and {Universidade Estadual de Campinas 
                         (UNICAMP)} and {Universidade Estadual de Campinas (UNICAMP)} and 
                         {Universidade Estadual de Campinas (UNICAMP)}",
                title = "Hydrological niche segregation defines forest structure and 
                         drought tolerance strategies in a seasonal Amazon forest",
              journal = "Journal of Ecology",
                 year = "2019",
               volume = "107",
                pages = "318--333",
             keywords = "2015 ENSO, Amazon functional diversity, cavitation, embolism 
                         resistance, hydraulic traits, root depth, stable isotopes, water 
                         potential.",
             abstract = "1. The relationship between rooting depth and above-ground 
                         hydraulic traits can potentially define drought resistance 
                         strategies that are important in determining species distribution 
                         and coexistence in seasonal tropical forests, and understanding 
                         this is important for predicting the effects of future climate 
                         change in these ecosystems. 2. We assessed the rooting depth of 12 
                         dominant tree species (representing c. 42% of the forest basal 
                         area) in a seasonal Amazon forest using the stable isotope ratios 
                         (\δ18O and \δ2 H) of water collected from tree xylem 
                         and soils from a range of depths. We took advantage of a major 
                         ENSO-related drought in 2015/2016 that caused substantial 
                         evaporative isotope enrichment in the soil and revealed water use 
                         strategies of each species under extreme conditions. We measured 
                         the minimum dry season leaf water potential both in a normal year 
                         (2014; \Ψnon-ENSO) and in an extreme drought year (2015; 
                         \ΨENSO). Furthermore, we measured xylem hydraulic traits 
                         that indicate water potential thresholds trees tolerate without 
                         risking hydraulic failure (P50 and P88). 3. We demonstrate that 
                         coexisting trees are largely segregated along a single 
                         hydrological niche axis defined by root depth differences, access 
                         to light and tolerance of low water potential. These differences 
                         in rooting depth were strongly related to tree size; diameter at 
                         breast height (DBH) explained 72% of the variation in the 
                         \δ18Oxylem. Additionally, \δ18Oxylem explained 49% of 
                         the variation in P50 and 70% of P88, with shallow-rooted species 
                         more tolerant of low water potentials, while \δ18O of xylem 
                         water explained 47% and 77% of the variation of minimum 
                         \Ψnon-ENSO and \ΨENSO. 4. We propose a new formulation 
                         to estimate an effective functional rooting depth, i.e. the likely 
                         soil depth from which roots can sustain water uptake for 
                         physiological functions, using DBH as predictor of root depth at 
                         this site. Based on these estimates, we conclude that rooting 
                         depth varies systematically across the most abundant families, 
                         genera and species at the Tapaj{\'o}s forest, and that 
                         understorey species in particular are limited to shallow rooting 
                         depths. 5. Our results support the theory of hydrological niche 
                         segregation and its underlying trade-off related to drought 
                         resistance, which also affect the dominance structure of trees in 
                         this seasonal eastern Amazon forest. 6. Synthesis. Our results 
                         support the theory of hydrological niche segregation and 
                         demonstrate its underlying trade-off related to drought resistance 
                         (access to deep water vs. tolerance of very low water potentials). 
                         We found that the single hydrological axis defining water use 
                         traits was strongly related to tree size, and infer that periodic 
                         extreme droughts influence community composition and the dominance 
                         structure of trees in this seasonal eastern Amazon forest.",
                  doi = "10.1111/1365-2745.13022",
                  url = "http://dx.doi.org/10.1111/1365-2745.13022",
                 issn = "0022-0477",
             language = "en",
           targetfile = "brum_hydrological.pdf",
        urlaccessdate = "04 dez. 2020"
}


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