Understanding the interactive effects of elevated CO2 concentration and water availability on tree functioning is fundamental for the advance of both forest science and global climate change research. In this study, Sánchez-Gómez et al. conduct a controlled experiment in growth chambers with clones of Pinus pinaster with contrasting drought tolerance to test the hypothesis that intraspecific variability in drought tolerance can be modulated by elevated [CO2].
Intraspecific variation in leaf gas exchange, growth rate and other leaf functional traits was analysed. They find that elevated [CO2] attenuates genotypic differences in drought tolerance, in terms of photosynthetic performance and growth, as compared with those observed at ambient [CO2]. This study suggests that elevated [CO2] can modify the range of drought tolerance across genotypes within tree species.