Fig. 2. Observations, modelled simulations, and the predictability of the leaf temperature response of net CO₂ assimilation (A_n) for individual species and plant functional types.

a The A_n temperature response of four representative cool grown species: Triticum aestivum (herb/grass), Quercus pubescens (temperate tree), Picea mariana (needle-leaf tree), and Deschampsia antarctica (herb/grass). For D. antarctica, an extremophile that was grown at 12 °C, the broken line between observations highlights the deviation from the model prediction below 30 °C for this species. Points are observations and the curves are the Rubisco carboxylation limited assimilation rates (A_c) with Rubisco deactivation included parameterised to cool grown plants (solid blue lines), or RuBP regeneration limited CO₂ assimilation rates (A_r) parameterised to cool grown plants (dotted blue lines). b Four representative warm grown species: Oryza sativa (grass), Cryptocarya laevigata (tropical tree), Eucalyptus camaldulensis (temperate tree), and Larrea divaricata (shrub). For L. divaricata, an extremophile that was grown at 44 °C, the broken line between observations highlights the deviation from the model prediction above 30 °C for this species. Points are observations and the curves are the A_c with Rubisco deactivation included for warm grown plants (solid red lines), or A_r for warm grown plants (dotted red lines). c, d Predictions of A_c which included Rubisco deactivation were plotted against corresponding observations for cool (c) and warm (d) grown plants. The coefficient of determination (r²), a 1:1 ratio (solid line), the root mean squared error (RMSE) between observed and predicted values (μmol m⁻² s⁻¹), and the bias in observations being greater than predictions (μmol m⁻² s^–1) for each growth environment are provided. Plant functional types are indicated by differing symbols and colours.