Table 7 Regression coefficients in the correlation of bark thickness (Bth) and of diameter of heartwood (Dh) with diameter of stem wood including bark (Dob), according to Eqs. (3) and (4). Note that heartwood is not distinguished for Norway spruce and beech. For silver birch, insufficient measurements of bark thickness were available
Tree species | Bark thickness (-) | Heartwood diameter (-) | ||||||
|---|---|---|---|---|---|---|---|---|
a | b | R 2 | n | c | d | R 2 | n | |
Larch | 0.045 | 0.010 | 0.75 | 60 | 0.86 | −2.82 | R² = 0.99 | 39 |
Spruce | 0.024 | −0.085 | 0.77 | 67 |  |  |  |  |
Fir | 0.049 | −0.093 |  0.81 | 111 | 0.69 | −3.02 | R² = 0.89 | 132 |
Pine | 0.046 | −0.15 |  0.53 | 156 | 0.46 | −1.76 | R² = 0.57 | 140 |
Beech | 0.011 | 0.14 | 0.77 | 62 | Â | Â | Â | Â |
Oak | 0.055 | 0.060 | 0.87 | 64 | 0.81 | −2.95 | R² = 0.99 | 35 |