Advertisement

The response of isoprene emission rate and photosynthetic rate to photon flux and nitrogen supply in aspen and white oak trees

Authors

  • M. E. Litvak,

    Corresponding author
    1. Department of Environmental, Population, and Organismic Biology, University of Colorado, Boulder, CO 80309, USA
      Marcy Litvak, Department of Environmental, Population and Organismic Biology, University of Colorado, Boulder, CO 80309–0334, USA
    Search for more papers by this author
  • F. Loreto,

    1. Department of Botany, University of Wisconsin, Madison, WI 53706, USA
    Search for more papers by this author
  • P. C. Harley,

    1. Department of Environmental, Population, and Organismic Biology, University of Colorado, Boulder, CO 80309, USA
    2. Atmospheric Chemistry Division, National Center for Atmospheric Research, Boulder, CO 80307, USA
    Search for more papers by this author
  • T. D. Sharkey,

    1. Department of Botany, University of Wisconsin, Madison, WI 53706, USA
    Search for more papers by this author
  • R. K. Monson

    1. Department of Environmental, Population, and Organismic Biology, University of Colorado, Boulder, CO 80309, USA
    Search for more papers by this author

Marcy Litvak, Department of Environmental, Population and Organismic Biology, University of Colorado, Boulder, CO 80309–0334, USA

ABSTRACT

Isoprene is the primary biogenic hydrocarbon emitted from temperate deciduous forest ecosystems. The effects of varying photon flux density (PFD) and nitrogen growth regimes on rates of isoprene emission and net photosynthesis in potted aspen and white oak trees are reported. In both aspen and oak trees, whether rates were expressed on a leaf area or dry mass basis, (1) growth at higher PFD resulted in significantly higher rates of isoprene emission, than growth at lower PFD, (2) there is a significant positive relationship between isoprene emission rate and leaf nitrogen concentration in both sun and shade trees, and (3) there is a significant positive correlation between isoprene emission rate and photosynthetic rate in both sun and shade trees. The greater capacity for isoprene emission in sun leaves was due to both higher leaf mass per unit area and differences in the biochemical and/or physiological properties that influence isoprene emission. Positive correlations between isoprene emission rate and leaf nitrogen concentration support the existence of mechanisms that link leaf nitrogen status to isoprene synthase activity. Positive correlations between isoprene emission rate and photosynthesis rate support previous hypotheses that isoprene emission plays a role in protecting photosynthetic mechanisms during stress.

Ancillary