Tree Allometrics

Equations / Aboveground biomass

Acacia-Commiphora total AGB, M8 (rho D2 H, crown width, D30)

Aboveground biomassEleven woody species of the Acacia-Commiphora biome (mixed)EthiopianaturalRead from the original paper
Many species, no single photo
Equation

As printed (Table 3, AGBTotal rows, p. 6; model form in Table 1, p. 4)

8a –0.6207 0.2108 0.4041 0.0911 0.4999 0.2052 0.4446 0.2240 0.40b 0.83b 0.83b

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

Aboveground biomass = exp(-0.6207 + 0.4041 * ln(rho * D^2 * H) + 0.4999 * ln(CD) + 0.4446 * ln(D30))
rho
Wood density (oven-dry mass / green volume), g/cm³
D
Diameter at breast height (1.3 m), cm
H
Total tree height, m
CD
Crown diameter, m
D30
Stem diameter at 30 cm, cm

Total aboveground dry biomass (stem + branches + foliage summed). In the paper D is DBH (cm), DSH30 is stem diameter at 30 cm (mapped to D30), CW is crown width (mapped to CD, m), rho is basic wood density (g/cm3). R2 shown is the printed R2 (Adj-R2 is within 0.01). No back-transformation correction factor is printed, so none is applied. The paper prints the mean D (12.61 cm) and a D range width of 29 cm but no min or max, so no DBH range is stored. RMSE printed in Table 3 is on the log scale. n = 140 is the full sample; Methods (p. 3) say 30% was held out for validation, so the fitted n may be ~98. The abstract and Results text say DSH10; Table 1 and the printed equations use DSH30, used here.

Source
AGBest. = exp {α + β1Ln (ρ.D2.H) + β2Ln (CW) + β3Ln (DSH30)}
model form · Table 1, p. 4
The biomass of the 140 individual trees was considered for biomass model development.
Trees measured · Methods, Biomass measurement, p. 3
8a –0.6207 0.2108 0.4041 0.0911 0.4999 0.2052 0.4446 0.2240 0.40b 0.83b 0.83b
R² · Table 3, AGBTotal, columns R2 / Adj-R2
Trees measured
140
R²
0.83
Method
ln-ln multiple linear regression (SAS); no correction factor stated
Where
Bena-Tsemay district, southern Ethiopia
Last checked
2026-11-02
Calculate
Height from
20.13
Aboveground biomass (kg)
9.46
Carbon (kg), ×0.47
34.69
CO₂e (kg), ×44/12
01020304050607080510152025303540DBH (cm)Aboveground biomass (kg)Aboveground 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 = 8, H = 4, rho = 0.7, CD = 3, D30 = 920.120.1Computed from the printed form
computed from the published form (coefficients as printed, no correction factor)
D = 15, H = 6, rho = 0.7, CD = 4.5, D30 = 1662.362.3Computed from the printed form
computed from the published form (coefficients as printed, no correction factor)
D = 25, H = 8, rho = 0.7, CD = 6, D30 = 26151.6151.6Computed from the printed form
computed from the published form (coefficients as printed, no correction factor)

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