Fig. 3.

Relationships between τ_soil, soil mean carbon age, and biomarker ¹⁴C age. (A and B) Plant-wax fatty-acid and (C and D) lignin-phenol ¹⁴C ages as a function of weighted-catchment τ_soil (Left, ref. 5), and soil mean carbon age (0 to 100 cm, Right, ref. 34). Solid and dashed black lines are reduced major-axis regression lines; reported values are the corresponding reduced major-axis regression slopes and r² values (Materials and Methods). Uncertainty (±1σ) is always smaller than marker points.