Figure 2.

Comparison of observed to optimal $V_{\mathrm{cmax}}^{\prime }$. Observed mean maximum rate of Rubisco carboxylation ($V_{\mathrm{cmax}}^{\prime }$) at 201 global sites plotted against the predicted $V_{\mathrm{cmax}}^{\prime }$value at that site from the theoretical model. Sites are coloured by Köppen climate classification. Tropical (first letter A), arid (first letter B), temperate (first letter C), boreal (first letter D) and polar (first letter E) regions are represented by red, yellow, green, blue and grey colours. Error bars represent standard errors of the mean. The solid black line is the best fit line from the reduced major axis regression. The grey‐shaded area represents a 95% confidence interval. The dotted black line is a 1:1 line. Köppen climate classification key: Af= tropical rainforest, Am= tropical monsoon, Aw= tropical wet savannah, BSh= hot arid steppe, BSk= cold arid steppe, BWh= hot arid desert, BWk= cold arid desert, Cfa= temperate hot summer without dry season, Cfb= temperate warm summer without dry season, Cfc= temperate cold summer without dry season, Csa= temperate hot summer with dry summer, Csb= temperate warm summer with dry summer, Cwa= temperate hot summer with dry winter, Cwb= temperate warm summer with dry winter, Dfa= boreal hot summer without dry season, Dfb= boreal warm summer without dry season, Dfc= boreal cold summer without dry season, Dsc= boreal cold summer with dry summer, Dwc= boreal cold summer with dry winter, EF= eternal winter, ET= tundra. A version of this figure with individual points can be found in the Supplementary Information (Figure S8).