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Seasonal shifts in isoprenoid emission compositions from three hyperdominant tree species in central Amazonia
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  • Eliane Gomes Alves,
  • Tyeen Taylor,
  • Michelle Robin ,
  • Debora Pinheiro de Oliveira,
  • Juliana Schietti,
  • Sergio Duvoisin Júnior,
  • Nora Zannoni,
  • Christoph Hartmann,
  • Jonathan. Williams,
  • José Francisco Gonçalves,
  • Jochen Schöngart,
  • Florian Wittmann,
  • Maria Piedade
Eliane Gomes Alves
Max Planck Institute for Biogeochemistry

Corresponding Author:[email protected]

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Tyeen Taylor
University of Miami
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Michelle Robin
Max Planck Institute for Biogeochemistry
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Debora Pinheiro de Oliveira
National Institute of Amazonian Research
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Juliana Schietti
Federal University of Amazonas
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Sergio Duvoisin Júnior
University of Amazonas State
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Nora Zannoni
Max Planck Institute for Chemistry
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Christoph Hartmann
Max Planck Institute for Chemistry
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Jonathan. Williams
Max Planck Institute for Chemistry
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José Francisco Gonçalves
National Institute of Amazonian Research
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Jochen Schöngart
National Institute of Amazonian Research
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Florian Wittmann
Karlsruhe Institute of Technology
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Maria Piedade
National Institute of Amazonian Research
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Abstract

Volatile isoprenoids regulate plant performance and atmospheric processes, and Amazon forests comprise the dominant source to the global atmosphere. Still, there is a poor understanding of how isoprenoid emission capacities vary in response to ecophysiological and environmental controls in Amazonian ecosystems. We measured isoprenoid emission capacities of Amazonian hyperdominant tree species—Protium hebetatum, Eschweilera grandiflora, Eschweilera coriacea — across seasons and along a topographic and edaphic environmental gradient in the central Amazon. From wet to dry season, both photosynthesis and isoprene emission capacities strongly declined, while emissions increased among the heavier isoprenoids—monoterpenes and sesquiterpenes. Plasticity across habitats was most evident in P. hebetatum, which emitted sesquiterpenes only in the dry season, at rates that significantly increased along the hydro-topographic gradient from white sands (shallow root water access) to upland (deep water table). We suggest that emission composition shifts are part of a plastic response to increasing abiotic stress (e.g., heat and drought) and reduced photosynthetic supply of substrates for isoprenoid synthesis. Our comprehensive measurements suggest that more emphasis should be placed on other isoprenoids besides isoprene in the context of abiotic stress responses. Shifting emission compositions have implications for atmospheric responses due to the strong variation in reactivity among isoprenoid compounds.