Tree Allometrics

Vachellia tortilis / Stem biomass

Vachellia tortilis stem biomass (Model 3)

Stem biomassVachellia tortilisEthiopiaRead from the original paperPeer-reviewed source
Photo of Vachellia tortilis
© Rabah Al-Shammary · CC BY · iNaturalist
Equation

As printed (Table 5, Models and Coefficients columns, Stem Model 3 row, p. 9)

Y = β₁d^β₂h^β₃; β₁ = 0.015, β₂ = 4.165, β₃ = −2.433

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

Stem biomass = 0.015 * D^4.165 * H^(-2.433)
D
Diameter at breast height (1.3 m), cm
H
Total tree height, m

Nonlinear power regression on the original scale; no back-transformation or correction is stated or applied. d is diameter at breast height, 1.3 m, and h is total height. For multi-stemmed trees use the square root of the sum of squared stem diameters at the relevant height (Eq. 1). The harvested stump-diameter range was 3.2–44.5 cm. The paper sets the stem cut-off point at a diameter of 2.5 cm.

Source
Model 3 Y = β1d β2h β3 0.015 4.165** − 2.433** 0.77 49.93 6.78 39.98 0.86 3
Equation · Table 5, Stem Model 3, p. 9
Stem
Output · Table 5, biomass component, p. 9
biomass (kg dry matter/
Units · Table 5 heading, p. 9
ith stem at stump or breast height (cm).
Units · Eq. 1 definition, p. 4
d: diameter at breast height (1.30 m)
Units · Table 5 note, p. 9
height of plant (m)
Units · Table 5 note, p. 9
kg per plant, n: 15
Trees measured · Table 5 note, p. 9
Model 3 Y = β1d β2h β3 0.015 4.165** − 2.433** 0.77 49.93 6.78 39.98 0.86 3
R² · Table 5, Stem Model 3, p. 9
non-linear power function
method · Abstract, p. 1
Vachellia tortilis
Taxon · Study area, p. 3
Adami Tullu Jido Kombolcha district
Where · Study area, p. 2
semi-arid climate zone
Where · Study area, p. 2
the stem cut-off point was set at a 2.5 cm diameter.
Output · Section 2.2.3, p. 5
Trees measured
15
R²
0.77
Method
nonlinear power regression
Where
Adami Tullu Jido Kombolcha district, Central Rift Valley, Ethiopia
Last checked
2026-11-05
Calculate
Height from
82
Stem biomass (kg)
38.5
Carbon (kg), ×0.47
141
CO₂e (kg), ×44/12

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 = 15, H = 38282Computed from the printed form
Computed from the printed Table 5 coefficients; no individual published prediction with all inputs is provided.

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