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Differences in xylem and leaf hydraulic traits explain differences in drought tolerance among mature Amazon rainforest trees

Powell, Thomas L. ; Wheeler, James K. ; Oliveira, Alex A. R. ; Costa, Antonio Carlos Lola ; Saleska, Scott R. ; Meir, Patrick ; Moorcroft, Paul R.

Global change biology, 2017-10, Vol.23 (10), p.4280-4293 [Periódico revisado por pares]

England: Blackwell Publishing Ltd

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  • Título:
    Differences in xylem and leaf hydraulic traits explain differences in drought tolerance among mature Amazon rainforest trees
  • Autor: Powell, Thomas L. ; Wheeler, James K. ; Oliveira, Alex A. R. ; Costa, Antonio Carlos Lola ; Saleska, Scott R. ; Meir, Patrick ; Moorcroft, Paul R.
  • Assuntos: Amazon rainforest ; Anthropogenic factors ; Biosphere ; Branches ; Brazil ; Bulk modulus ; Canopies ; Canopy ; Climate ; Climate Change ; Composition ; Computational fluid dynamics ; Demographics ; Drought ; Drought resistance ; Droughts ; Ecosystems ; Elasticity ; Environment models ; Fluid flow ; Forests ; Human influences ; Hydraulics ; Leaves ; Modulus of elasticity ; Mortality ; Osmotic potential ; Physiology ; plant hydraulics ; Plant Leaves ; plant traits ; Rainforest ; Rainforests ; Soil ; Soil types ; Species ; Terrestrial environments ; Trees ; Tropical Climate ; Tropical forests ; Turgor ; turgor loss point ; Water ; Water potential ; Wood ; Xylem
  • É parte de: Global change biology, 2017-10, Vol.23 (10), p.4280-4293
  • Notas: ObjectType-Article-1
    SourceType-Scholarly Journals-1
    ObjectType-Feature-2
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    USDOE
  • Descrição: Considerable uncertainty surrounds the impacts of anthropogenic climate change on the composition and structure of Amazon forests. Building upon results from two large‐scale ecosystem drought experiments in the eastern Brazilian Amazon that observed increases in mortality rates among some tree species but not others, in this study we investigate the physiological traits underpinning these differential demographic responses. Xylem pressure at 50% conductivity (xylem‐P50), leaf turgor loss point (TLP), cellular osmotic potential (πo), and cellular bulk modulus of elasticity (ε), all traits mechanistically linked to drought tolerance, were measured on upper canopy branches and leaves of mature trees from selected species growing at the two drought experiment sites. Each species was placed a priori into one of four plant functional type (PFT) categories: drought‐tolerant versus drought‐intolerant based on observed mortality rates, and subdivided into early‐ versus late‐successional based on wood density. We tested the hypotheses that the measured traits would be significantly different between the four PFTs and that they would be spatially conserved across the two experimental sites. Xylem‐P50, TLP, and πo, but not ε, occurred at significantly higher water potentials for the drought‐intolerant PFT compared to the drought‐tolerant PFT; however, there were no significant differences between the early‐ and late‐successional PFTs. These results suggest that these three traits are important for determining drought tolerance, and are largely independent of wood density—a trait commonly associated with successional status. Differences in these physiological traits that occurred between the drought‐tolerant and drought‐intolerant PFTs were conserved between the two research sites, even though they had different soil types and dry‐season lengths. This more detailed understanding of how xylem and leaf hydraulic traits vary between co‐occuring drought‐tolerant and drought‐intolerant tropical tree species promises to facilitate a much‐needed improvement in the representation of plant hydraulics within terrestrial ecosystem and biosphere models, which will enhance our ability to make robust predictions of how future changes in climate will affect tropical forests. Associations between hydraulic traits and drought tolerance have been inferred for tropical tree species based on abundances in ecosystems with contrasting soils or precipitation, but it has never been experimentally demonstrated, as we have done, on species growing in direct competition in the Amazon rainforest. Our results show that when exposed to experimental drought, species with higher mortality rates had higher vulnerability to cavitation, turgor loss point, and leaf osmotic potential compared to species with lower mortality rates. These patterns were spatially conserved between tropical forests with contrasting soil types—clay versus sandy soil.
  • Editor: England: Blackwell Publishing Ltd
  • Idioma: Inglês
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  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

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