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Summary Generalised dose–response curves are essential to understand how plants acclimate to atmospheric CO 2 . We carried out a meta‐analysis of 630 experiments in which C 3 plants were experimentally grown at different CO 2 under relatively benign conditions, and derived dose–response curves for 85 phenotypic traits. These curves were characterised by form, plasticity, consistency and reliability. Considered over a range of 200–1200 µmol mol −1 CO 2 , some traits more than doubled (e.g. area‐based photosynthesis; intrinsic water‐use efficiency), whereas others more than halved (area‐based transpiration). At current atmospheric CO 2 , 64% of the total stimulation in biomass over the 200–1200 µmol mol −1 range has already been realised. We also mapped the trait responses of plants to CO 2 against those we have quantified before for light intensity. For most traits, CO 2 and light responses were of similar direction. However, some traits (such as reproductive effort) only responded to light, others (such as plant height) only to CO 2 , and some traits (such as area‐based transpiration) responded in opposite directions. This synthesis provides a comprehensive picture of plant responses to CO 2 at different integration levels and offers the quantitative dose–response curves that can be used to improve global change simulation models.
Poorter et al. (Sun,) studied this question.