1. Elevated CO₂ increases tree-level intrinsic water use efficiency: insights from carbon and oxygen isotope analyses in tree rings across three forest FACE sites.
- Author
-
Battipaglia G, Saurer M, Cherubini P, Calfapietra C, McCarthy HR, Norby RJ, and Francesca Cotrufo M
- Subjects
- Carbon Isotopes, Climate, Italy, North Carolina, Oxygen Isotopes, Partial Pressure, Photosynthesis drug effects, Plant Stomata drug effects, Plant Stomata physiology, Regression Analysis, Tennessee, Time Factors, Air analysis, Carbon Dioxide pharmacology, Trees drug effects, Trees physiology, Water metabolism
- Abstract
Elevated CO₂ increases intrinsic water use efficiency (WUE(i) ) of forests, but the magnitude of this effect and its interaction with climate is still poorly understood. We combined tree ring analysis with isotope measurements at three Free Air CO₂ Enrichment (FACE, POP-EUROFACE, in Italy; Duke FACE in North Carolina and ORNL in Tennessee, USA) sites, to cover the entire life of the trees. We used δ¹³C to assess carbon isotope discrimination and changes in water-use efficiency, while direct CO₂ effects on stomatal conductance were explored using δ¹⁸O as a proxy. Across all the sites, elevated CO₂ increased ¹³C-derived water-use efficiency on average by 73% for Liquidambar styraciflua, 77% for Pinus taeda and 75% for Populus sp., but through different ecophysiological mechanisms. Our findings provide a robust means of predicting water-use efficiency responses from a variety of tree species exposed to variable environmental conditions over time, and species-specific relationships that can help modelling elevated CO₂ and climate impacts on forest productivity, carbon and water balances., (© 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.)
- Published
- 2013
- Full Text
- View/download PDF