Increased water-use efficiency does not lead to enhanced tree growth under xeric and mesic conditions
Article first published online: 17 MAR 2014
© 2014 The Authors. New Phytologist © 2014 New Phytologist Trust
Volume 203, Issue 1, pages 94–109, July 2014
How to Cite
Lévesque, M., Siegwolf, R., Saurer, M., Eilmann, B. and Rigling, A. (2014), Increased water-use efficiency does not lead to enhanced tree growth under xeric and mesic conditions. New Phytologist, 203: 94–109. doi: 10.1111/nph.12772
- Issue published online: 28 MAY 2014
- Article first published online: 17 MAR 2014
- Manuscript Accepted: 20 FEB 2014
- Manuscript Received: 28 NOV 2013
- Swiss State Secretariat for Education and Research. Grant Number: FP0703
- BAFU/WSL Research Program
- carbon isotope;
- climate change;
- Larix ;
- oxygen isotope;
- Picea ;
- Pinus ;
- Pseudotsuga ;
- tree ring
- Higher atmospheric CO2 concentrations (ca) can under certain conditions increase tree growth by enhancing photosynthesis, resulting in an increase of intrinsic water-use efficiency (iWUE) in trees. However, the magnitude of these effects and their interactions with changing climatic conditions are still poorly understood under xeric and mesic conditions.
- We combined radial growth analysis with intra- and interannual δ13C and δ18O measurements to investigate growth and physiological responses of Larix decidua, Picea abies, Pinus sylvestris, Pinus nigra and Pseudotsuga menziesii in relation to rising ca and changing climate at a xeric site in the dry inner Alps and at a mesic site in the Swiss lowlands.
- iWUE increased significantly over the last 50 yr by 8–29% and varied depending on species, site water availability, and seasons. Regardless of species and increased iWUE, radial growth has significantly declined under xeric conditions, whereas growth has not increased as expected under mesic conditions. Overall, drought-induced stomatal closure has reduced transpiration at the cost of reduced carbon uptake and growth.
- Our results indicate that, even under mesic conditions, the temperature-induced drought stress has overridden the potential CO2 ‘fertilization’ on tree growth, hence challenging today's predictions of improved forest productivity of temperate forests.