Home

Editors

Contents

Contribute

Subscribe

Contact

Effect of elevated CO₂ on monoterpene emission of young Quercus ilex trees and its relation to structural and ecophysiological parameters

Michael Staudt (1), Richard Joffre (1), Serge Rambal (1) and Jürgen Kesselmeier (2)

1. DREAM unit, Centre d'Ecologie Fonctionelle et Evolutive CNRS, 1919 Route de Mende, 34293 Montpellier cedex 5, France / 2. Max Planck Institute for Chemistry, Biogeochemistry Department, P.O. Box 3060, 55020 Mainz, Germany / Received July 20, 2000

Summary

We investigated growth, leaf monoterpene emission, gas exchange, leaf structure and leaf chemical composition of 1-year-old Quercus ilex L. seedlings grown in ambient (350 μl l^–1) and elevated (700 μl l^–1) CO₂ concentrations ([CO₂]). Monoterpene emission and gas exchange were determined at constant temperature and irradiance (25 °C and 1000 μmol m^–2 s^–1 of photosynthetically active radiation) at an assay [CO₂] of 350 or 700 μl l^–1. Measurements were made on intact shoots after the end of the growing season between mid-October and mid-February. On average, plants grown in elevated [CO₂] had significantly increased foliage biomass (about 50%). Leaves in the elevated [CO₂] treatment were significantly thicker and had significantly higher concentrations of cellulose and lignin and significantly lower concentrations of nitrogen and minerals than leaves in the ambient [CO₂] treatment. Leaf dry matter density and leaf concentrations of starch, soluble sugars, lipids and hemi-cellulose were not significantly affected by growth in elevated [CO₂]. Monoterpene emissions of seedlings were significantly increased by elevated [CO₂] but were insensitive to short-term changes in assay [CO₂]. On average, plants grown in elevated [CO₂] had 1.8-fold higher monoterpene emissions irrespective of the assay [CO₂]. Conversely, assay [CO₂] rapidly affected photosynthetic rate, but there was no apparent long-term acclimation of photosynthesis to growth in elevated [CO₂]. Regardless of growth [CO₂], photosynthetic rates of all plants almost doubled when the assay [CO₂] was switched from 350 to 700 μl l^–1. At the same assay [CO₂], mean photosynthetic rates of seedlings in the two growth CO₂ treatments were similar. The percentage of assimilated carbon lost as monoterpenes was not significantly altered by CO₂ enrichment. Leaf emission rates were correlated with leaf thickness, leaf concentrations of cellulose, lignin and nitrogen, and total plant leaf area. In all plants, monoterpene emissions strongly declined during the winter independently of CO₂ treatment. The results are discussed in the context of the acquisition and allocation of resources by Q. ilex seedlings and evaluated in terms of emission predictions.

Keywords: carbon allocation, carbon dioxide enrichment, global change, growth, Holm oak, leaf structure, photosynthesis, volatile organic compound emission.

---

ISSN 0829-318X Copyright © 2002–2008 Heron Publishing