Circadian rhythms constrain leaf and canopy gas exchange in an Amazonian forest

Christopher E. Doughty, Michael L. Goulden, Scott D. Miller, Humberto R. Da Rocha

Research output: Contribution to journalArticlepeer-review

35 Scopus citations

Abstract

We used a controlled-environment leaf gas-exchange system and the micrometeorological technique eddy covariance to determine whether circadian rhythms constrain the rates of leaf and canopy gas exchange in an Amazonian forest over a day. When exposed to continuous and constant light for 20 to 48 hours leaves of eleven of seventeen species reduced their photosynthetic rates and closed their stomata during the normally dark period and resumed active gas exchange during the normally light period. Similarly, the rate of whole-forest CO2 uptake at a predetermined irradiance declined during the late afternoon and early morning and increased during the middle of the day. We attribute these cycles to circadian rhythms that are analogous to ones that have been reported for herbaceous plants in the laboratory. The importance of endogenous gas exchange rhythms presents a previously unrecognized challenge for efforts to both interpret and model land-atmosphere energy and mass exchange.

Original languageEnglish (US)
Article numberL15404
JournalGeophysical Research Letters
Volume33
Issue number15
DOIs
StatePublished - Aug 2006
Externally publishedYes

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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