Photosynthesis and stomatal conductance responses of poplars to free-air CO2 enrichment (PopFACE) during the first growth cycle and immediately following coppice
Article first published online: 25 JUL 2003
Volume 159, Issue 3, pages 609–621, September 2003
How to Cite
Bernacchi, C. J., Calfapietra, C., Davey, P. A., Wittig, V. E., Scarascia-Mugnozza, G. E., Raines, C. A. and Long, S. P. (2003), Photosynthesis and stomatal conductance responses of poplars to free-air CO2 enrichment (PopFACE) during the first growth cycle and immediately following coppice. New Phytologist, 159: 609–621. doi: 10.1046/j.1469-8137.2003.00850.x
- Issue published online: 25 JUL 2003
- Article first published online: 25 JUL 2003
- Received: 12 February 2003 Accepted: 9 May 2003; doi: 10.1046/j.1469-8137.2003.00850.x
- Free Air CO2 Enrichment (FACE);
- atmospheric change;
- climate change;
- elevated CO2;
- photosynthetic electron transport;
- Populus spp
- • Using the Poplar Free Air CO2 Enrichement (PopFACE) facility we investigated the effects of elevated [CO2] on the diurnal and growth cycle responses of photosynthesis and conductance in three poplar species.
- • In situ diurnal measurements of photosynthesis were made on Populus alba, P. nigra and P. ×euramericana and, in parallel, in vivo maximum capacity for carboxylation (Vc,max) and maximum rates of electron transport (Jmax) were determined by gas exchange measurement.
- • Light saturated (Asat) and daily integrated (A′) photosynthesis increased at elevated [CO2] in all species. Elevated [CO2] decreased Vc,max and Jmax for P. nigra and Jmax for P.¥euramericana but had no effect on stomatal conductance in any of the species throughout the first growth cycle. During post-coppice re-growth, elevated [CO2] did not increase Asat in P. nigra and P.×euramericana due to large decreases in Vc,max and Jmax.
- • A 50% increase in [CO2] under these open-air field conditions resulted in a large and sustained increase in Asat. Although there were some differences between the species, these had little effect on photosynthetic rates at the growth [CO2]. Nevertheless the results show that even fast growing trees grown without rooting volume restriction in the open may still show some down-regulation of photosynthetic potential at elevated [CO2].