Fig. 5.

Age-dependent modifications in leaf nitrogen content per unit area (N_A) at a constant average daily integrated quantum flux density (Q_int) of 12 mol m^-2 d^-1 (a-d) and the degree of explained variance (r²) of Q_int vs. N_A relationships (e-h) in different plant life forms. Figure 1b demonstrates sample data fits. Symbols are defined in Fig. 2 and data presentation follows Fig. 3.