Dominant trees (white triangles, dashed line: y = 1.06x − 0.34, R² = 0.92, P < 0.001) produced significantly more heartwood (HW) per unit area of trunk, compared to co-dominant (white circles, solid line: y = 1.1x − 0.44, R² = 0.90, P < 0.001) and suppressed trees (black squares, dotted line: y = 1.09x − 0.36, R² = 0.96, P < 0.001). CSA: cross-sectional area.