Phenotypic plasticity controls regional-scale variation in Quercus variabilis leaf δ13C

Key message The variation of Quercus variabilis leaf δ 13 C along latitude resulted primarily from phenotypic acclimation to climate. The determination of relative contribution by genetic adaptation and phenotypic acclimation to leaf δ 13 C variation helps the use of this index for reconstructing paleoclimates, developing terrestrial carbon dynamic models, and evaluating plant water use efficiency under predicted climate change. Using a 4-year in situ investigation across eastern China and a common garden experiment to explore plastic versus adaptive effects on the variation of leaf δ 13 C in Quercus variabilis , a widely distributed, economically important species in China. The leaf δ 13 C of in situ populations ranged from −24.05 to −30.74 ‰, and increased significantly with latitude, which was positively related to index of aridity, and negatively to mean annual temperature. However, there was little variation in leaf δ 13 C of seedlings from 16 populations planted in a common garden. These findings indicate the dominance of phenotypic acclimation in leaf δ 13 C variation. The hierarchical partitioning analysis further suggested that observed changes of in situ leaf δ 13 C had little association with leaf mass per area and nitrogen. These results suggest that Q. variabilis is physiologically flexible in acclimation to rapid climate change and can be a model plant species for studying the impacts of climate change on plant ecophysiology.