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Figure 1

(a) Measurement and classification of growth ring angle: rift = α ≤ 90°; half-rift = α ≤ 60°; tangential = α ≤ 30° and b) red heartwood combinations (NRH = no red heartwood; WRH = with red heartwood).
(a) Measurement and classification of growth ring angle: rift = α ≤ 90°; half-rift = α ≤ 60°; tangential = α ≤ 30° and b) red heartwood combinations (NRH = no red heartwood; WRH = with red heartwood).