Fig. 1: Relationships between leaf photosynthetic characteristics and leaf N and P for diverse woody species across continents.

a, b Relationships between mass-based photosynthetic parameters and leaf N concentration (N_mass) for tropical and subtropical trees across four continents, for species grouped into two leaf P (P_mass) classes, “low P” (P < 0.92 mg g⁻¹) and “moderate P” (P ≥ 0.92 mg g⁻¹). Low P data and lines in a, b are plum-coloured, with moderate P species shown as grey and black. Lines are least-squares fits and the shaded areas are the 95% CI regions. Each point represents the mean of a species-site combination, where different symbols of the same colour denote different continents and there are n = 445 species-site combinations. c, d The relationships between mass-based photosynthetic parameters and leaf phosphorus concentration for tropical and subtropical trees across four continents, with the shaded zone denoting the 95% CI. Least-squares fits and statistics for the lines in a–d are shown in Table 1. Photosynthetic parameters are a, b leaf mass-based carboxylation capacity normalised to 25 °C (V_{cmax_mass}), and c, d leaf mass-based RuBP regeneration capacity normalised to 25 °C (J_{max_mass}).