Long-term response of photosynthesis to elevated carbon dioxide in a Florida scrub-oak ecosystem

Elizabeth A. Ainsworth, Phillip A. Davey, Graham J. Hymus, Bert G. Drake, Stephen P. Long

Research output: Contribution to journalArticle

Abstract

The response of photosynthesis was analyzed during canopy closure in a Florida scrub-oak ecosystem exposed to elevated [CO2] (704 μmol CO2/mol air; concentration of CO2). The species were measured on six occasions, covering different seasons, during the third and fourth year of exposure to elevated [CO2]. The entire regrowth cycle of this community has been under elevated [CO2], providing a rare opportunity to assess the differential responses of species during the critical phase of canopy closure. Measurements were taken in order to determine both season-specific and species-specific differences in the response of photosynthesis to elevated [CO2]. Photosynthesis was measured with an open-gas exchange system, and in vivo rates of Rubisco carboxylation (Vc,max) and electron transport (Jmax) were derived to assess changes in the photosynthetic capacity in the codominant, evergreen oak species. Quercus myrtifolia did not show any change in photosynthetic capacity with prolonged exposure to elevated [CO2] during any season, and as a result the increase in photosynthesis due to the increased supply of CO2 was sustained at 72%. The codominant, Q. geminata, showed a loss of photosynthetic capacity with growth at elevated [CO2], such that during most measurement periods light-saturated photosynthesis in leaves grown and measured at elevated [CO2] was no higher than in leaves grown and measured at ambient CO2. A third oak, Q. chapmanii, showed a response similar to that of Q. myrtifolia. This suggests that at the critical phase of canopy closure in a woody community, elevation of [CO2] causes a species-dependent and time-dependent change in the capacity of the codominants to acquire carbon and energy.

Original languageEnglish (US)
Pages (from-to)1267-1275
Number of pages9
JournalEcological Applications
Volume12
Issue number5
DOIs
StatePublished - Oct 2002

Keywords

  • Canopy closure
  • Climate change
  • Elevated CO
  • Florida scrub oak
  • Intergeneric variation
  • Interspecific variation
  • Photosynthesis
  • Quercus
  • Rubisco

ASJC Scopus subject areas

  • Ecology

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