Carbon Flux and Growth in Mature Deciduous Forest Trees Exposed to Elevated CO2
- Christian Körner1,*,
- Roman Asshoff1,
- Olivier Bignucolo1,
- Stephan Hättenschwiler1,2,
- Sonja G. Keel3,
- Susanna Peláez-Riedl1,
- Steeve Pepin1,4,
- Rolf T. W. Siegwolf3,
- Gerhard Zotz1
- 1 Institute of Botany, University of Basel, Schönbeinstrasse 6, CH-4056 Basel, Switzerland.
- 2 Center of Functional Ecology and Evolution, CEFE-CNRS, 1919, route de Mende, F-34293 Montpellier cedex 5, F-34293 France.
- 3 Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland.
- 4 Faculté des sciences de l'agriculture et de l'alimentation, Pavillon Paul-Comtois, Université Laval, Québec (Qc) G1K 7P4, Canada.
- ↵* To whom correspondence should be addressed. E-mail: ch.koerner{at}unibas.ch
Abstract
Whether rising atmospheric carbon dioxide (CO2) concentrations will cause forests to grow faster and store more carbon is an open question. Using free air CO2 release in combination with a canopy crane, we found an immediate and sustained enhancement of carbon flux through 35-meter-tall temperate forest trees when exposed to elevated CO2. However, there was no overall stimulation in stem growth and leaf litter production after 4 years. Photosynthetic capacity was not reduced, leaf chemistry changes were minor, and tree species differed in their responses. Although growing vigorously, these trees did not accrete more biomass carbon in stems in response to elevated CO2, thus challenging projections of growth responses derived from tests with smaller trees.
- Received for publication 25 April 2005.
- Accepted for publication 21 July 2005.
