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Table 1 Species group above-ground forest tree biomass (AGB kg tree−1) equations

From: Model errors in tree biomass estimates computed with an approximation to a missing covariance matrix

Species # Equation
\(\widehat{{\text{AGB}}} =\)
\(\hat{R}^{2}\) \(\hat{\sigma }_{e}^{2}\)
103 kg
Wts
BEECHa 1 \(0.901{\text{DBH}}^{2} - 6.382\sqrt {\text{DBH} \times {\text{HT}}}\) 0.96 75.3 n.a.
2 \(\left( {9.645{\text{DBH}} - 0.648\sqrt {\text{HT}} } \right)^{2}\) 0.95 79.2 n.a.
SPRUCEa 5 \(0.447{\text{DBH}}^{2} - 1.189\sqrt {\text{DBH} \times {\text{HT}}}\) 0.98 18.7 n.a.
6 \(\left( {0.634{\text{DBH}} - 0.426\sqrt {\text{HT}} } \right)^{2}\) 0.98 18.2 n.a.
PINEa 9 \(0.450{\text{DBH}}^{2} - 0.014\sqrt {\text{DBH} \times {\text{HT}}}\) 0.98 14.5 n.a.
10 \(0.658{\text{DBH}}^{2} - 0.124\sqrt {\text{DBH} \times {\text{HT}}}\) 0.98 14.5 n.a.
BEECH 3 \(0.887{\text{DBH}}^{2} - 6.487\sqrt {\text{DBH} \times {\text{HT}}}\) 0.96 74.4 DBH−2
4 \(\left( {10.127{\text{DBH}} - 1.167\sqrt {\text{HT}} } \right)^{2}\) 0.95 75.3 DBH−2
SPRUCE 7 \(0.492{\text{DBH}}^{2} - 1.409\sqrt {\text{DBH} \times {\text{HT}}}\) 0.97 19.0 DBH−2
8 \(\left( {0.689{\text{DBH}} - 0.064\sqrt {\text{HT}} } \right)^{2}\) 0.97 18.7 DBH−2
PINE 11 \(0.479{\text{DBH}}^{2} - 1.927\sqrt {\text{DBH} \times {\text{HT}}}\) 0.97 14.7 DBH−2
12 \(0.690{\text{DBH}}^{2} - 0.205\sqrt {\text{DBH} \times {\text{HT}}}\) 0.97 14.5 DBH−2
BEECHb 13 \(Exp\left[ {0.006 + 10.933\,\frac{\text{DBH}}{\text {DBH} + 21.216}} \right]\) 0.99c n.a. n.a.
SPRUCEb 14 \(Exp\left[ { - 1.694 + 10.825\frac{\text{DBH}}{\text{DBH} + 11.816}} \right]\) 0.99c n.a. n.a.
PINEb 15 \(Exp\left[ { - 2.688 + 10.745\,\frac{\text{DBH}}{\text{DBH} + 8.062}} \right]\) 0.99c n.a. n.a.
  1. Sample size is 50 trees per species group.
  2. aBWI-1987 Predictions of AGB times a uniformly distributed random error [0.9,1.1] fitted to DBH (mm) and HT (dm).
  3. bGeneralized AGB equations from Table 8 (Temperate zone) in Muukkonen P and Heiskanen J [76]. DBH is in centimeters (cm).
  4. cAmount of variation in predicted AGB values captured by the generalized equation.
  5. Data were selected from 335 plots from the 1987 (West) German national forest inventory (BWI-1987). Plots were dominated by one of the three species groups. Selected trees have a DBH ≥ 7 cm, and were selected with a probability proportional to their basal area at breast height (basal area factor of 4), [77, ch. 8].