Equations / Stem biomass
Pinus cembroides stem biomass from DBH (cubic in ln D)
As printed (Cuadro 3 (Bf, modelo 4); R2 ajustada 0.75 in Cuadro 5)
In this library's units, ready to compute (kg)
Stem biomass = exp(-95.506 + 133.347*ln(D) - 61.223*(ln(D))^2 + 9.459*(ln(D))^3)D- Diameter at breast height (1.3 m), cm
Bf = stem biomass, selected as best model for stem in P. cembroides (Resultados). The cubic term in ln D has a very large cancelling coefficient set; the fit is only meaningful inside the sampled DBH range. Decimal point in the original. Plantation 22 years old. Biomass by the indirect Adelaide method (leaves-branches by reference branch, stem by Smalian volume times basic density), so the stem and total values are not weighed directly. Cuadro 5 R2 is the adjusted R2. The paper prints no correction factor for the ln back-transform, so none is applied. Ranges are from Cuadro 2 (n = 50).
doi:10.29298/rmcf.v9i47.172 · Open access · copy we read
ln B = β0 + β1 ln(Dn) + β2 ln(Dn)2 + β3 ln(Dn)3 + ε
con una muestra de 50 árboles por especie
- Trees measured
- 50
- DBH range
- 6.1–11 cm
- Height range
- 2.9–4.4 m
- R²
- 0.75
- Method
- ln-ln least squares in R; no correction factor stated
- Where
- Cuauhtémoc and El Recreo ejidos, Saltillo, Coahuila
- Last checked
- 2026-11-02
Shaded: the DBH range the model was fitted on. Other inputs held at the values above.
On every build, the library's form and the paper's own form (in its units) must both give these values within 1%.
| Inputs | Expected | We get | From |
|---|---|---|---|
| D = 7 | 6.34 | 6.34 | Computed from the printed form computed from the published form (coefficients as printed, no correction factor) |
| D = 9 | 9.52 | 9.52 | Computed from the printed form computed from the published form (coefficients as printed, no correction factor) |
| D = 11 | 14 | 14 | Computed from the printed form computed from the published form (coefficients as printed, no correction factor) |
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