Use este identificador para citar ou linkar para este item: https://repositorio.inpa.gov.br/handle/1/16864
Título: Causes of reduced leaf-level photosynthesis during strong El Niño drought in a Central Amazon forest
Autor: Santos, Victor Alexandre Hardt Ferreira dos
Ferreira, Marciel José
Rodrigues, J. V. F. C.
Garcia, Maquelle Neves
Ceron, João Vitor Barbosa
Nelson, Bruce Walker
Saleska, Scott Reid
Palavras-chave: Chlorophyll
Climate Change
Drought Stress
El Nino
Extreme Event
Photosynthesis
Stomatal Conductance
Tropical Forest
Warming
Amazonia
Drought
El Nino
Forest
Photosynthesis
Physiology
Plant Leaf
Season
Tree
Droughts
El Nino-southern Oscillation
Forests
Photosynthesis
Plant Leaves
Seasons
Trees
Data do documento: 2018
Revista: Global Change Biology
É parte de: Volume 24, Número 9, Pags. 4266-4279
Abstract: Sustained drought and concomitant high temperature may reduce photosynthesis and cause tree mortality. Possible causes of reduced photosynthesis include stomatal closure and biochemical inhibition, but their relative roles are unknown in Amazon trees during strong drought events. We assessed the effects of the recent (2015) strong El Niño drought on leaf-level photosynthesis of Central Amazon trees via these two mechanisms. Through four seasons of 2015, we measured leaf gas exchange, chlorophyll a fluorescence parameters, chlorophyll concentration, and nutrient content in leaves of 57 upper canopy and understory trees of a lowland terra firme forest on well-drained infertile oxisol. Photosynthesis decreased 28% in the upper canopy and 17% in understory trees during the extreme dry season of 2015, relative to other 2015 seasons and was also lower than the climatically normal dry season of the following non-El Niño year. Photosynthesis reduction under extreme drought and high temperature in the 2015 dry season was related only to stomatal closure in both upper canopy and understory trees, and not to chlorophyll a fluorescence parameters, chlorophyll, or leaf nutrient concentration. The distinction is important because stomatal closure is a transient regulatory response that can reverse when water becomes available, whereas the other responses reflect more permanent changes or damage to the photosynthetic apparatus. Photosynthesis decrease due to stomatal closure during the 2015 extreme dry season was followed 2 months later by an increase in photosynthesis as rains returned, indicating a margin of resilience to one-off extreme climatic events in Amazonian forests. © 2018 John Wiley & Sons Ltd
DOI: 10.1111/gcb.14293
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