Tree Allometrics

Equations / Stem biomass

Stem biomass from DBH, height and wood density (M9)

Stem biomassSeven dominant species of Chilimo forest (Juniperus procera, Podocarpus falcatus, Olea africana, Allophylus abyssinicus, Olinia rochetiana, Rhus glutinosa, Scolopia theifolia)EthiopianaturalRead from the original paper

Fitted on these 7 species: Juniperus procera, Podocarpus falcatus, Olea africana, Allophylus abyssinicus, Olinia rochetiana, Rhus glutinosa, Scolopia theifolia

2 of the 7 species it was fitted on · iNaturalist photos, hover for credit
Equation

As printed (Table 1 and Table 6)

M9 ln(b) = ln(β0) + β1 ln(d) + β2 ln(h) + β3 ln(ρ) + ε ... -3.142 1.847 0.945 0.274*

In this library's units, ready to compute (kg)

Stem biomass = 1.001 * (exp(-3.142 + 1.847 * ln(D) + 0.945 * ln(H) + 0.274 * ln(rho)))
D
Diameter at breast height (1.3 m), cm
H
Total tree height, m
rho
Wood density (oven-dry mass / green volume), g/cm³

Stem biomass only (branches and leaves not measured), computed as stem volume times basic wood density of each species, so dry mass. Range in fit is for the 194 sampled trees (Section 3.1). The wood density coefficient (0.274) is marked non-significant at alpha = 0.05 in Table 6. Back-transform CF 1.001 from Table S4 applied in expression.

Source
A total of 193 sampled trees from seven dominant tree species were used to develop the equations.
Trees measured · Abstract
The diameter, total height, and wood density ranged between 6.2 and 85.0 cm, 5.6 and 27.4 m
DBH range · Section 3.1
CF 1.001
Correction factor · Supplementary Table S4, p. 293
Trees measured
193
DBH range
6.2–85 cm
Height range
5.6–27.4 m
Correction factor
1.001 (applied)
Method
Robust linear regression (rlm, Tukey bisquare) of ln(response) on ln predictors
Where
Chilimo dry Afromontane forest, central Ethiopia
Last checked
2026-11-02
Calculate
Height from
99.5
Stem biomass (kg)
46.8
Carbon (kg), ×0.47
172
CO₂e (kg), ×44/12
Fitted DBH range0100200300400510152025303540DBH (cm)Stem biomass (kg)Stem biomass

Shaded: the DBH range the model was fitted on. Other inputs held at the values above.

Checks this equation passes

On every build, the library's form and the paper's own form (in its units) must both give these values within 1%.

InputsExpectedWe getFrom
D = 20, H = 12, rho = 0.699.599.5Computed from the printed form
hand-computed from the published form; CF 1.001 applied
D = 50, H = 20, rho = 0.6876876Computed from the printed form
hand-computed from the published form; CF 1.001 applied

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