Vachellia tortilis stem biomass (Model 4)

Stem biomassVachellia tortilisEthiopiaRead from the original paperPeer-reviewed sourceNot fully checked

Not fully checked: The multiplier is printed as 0.001 with only one significant digit; obtain the unrounded coefficient before relying on precision.

Equation

As printed (Table 5, Models and Coefficients columns, Stem Model 4 row, p. 9)

Y = β₁dₛₕ^β₂h^β₃; β₁ = 0.001, β₂ = 4.169, β₃ = −1.298

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

Stem biomass = 0.001 * D30^4.169 * H^(-1.298)

D30: Stem diameter at 30 cm, cm
H: Total tree height, m

Nonlinear power regression on the original scale; no back-transformation or correction is stated or applied. dsh is diameter at 30 cm above ground and h is total height. For multi-stemmed trees use the square root of the sum of squared stem diameters at that 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

Eshete, A., Getnet, D., Yilma, Z., Chimsa, D. & Befikadu, E. (2026). Aboveground biomass estimation of Vachellia tortilis (Forssk. Galasso & Banfi) for sustainable bioenergy production in the Central Rift Valley, Ethiopia. Discover Forests, 2, 49.

doi:10.1007/s44415-026-00110-y · Peer-reviewed · Open access · copy we read

Model 4 Y = β1dshβ2h β3 0.001 4.169*** − 1.298* 0.97 27.965 − 1.415 22.50 0.77 1

Equation · Table 5, Stem Model 4, 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

dsh:stump diameter at 30 cm height; h: total

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 4 Y = β1dshβ2h β3 0.001 4.169*** − 1.298* 0.97 27.965 − 1.415 22.50 0.77 1

R² · Table 5, Stem Model 4, 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: 0.97
Method: nonlinear power regression
Where: Adami Tullu Jido Kombolcha district, Central Rift Valley, Ethiopia
Last checked: 2026-11-05

Calculate

D30 (cm)Height (m)

Height from

63.8

Stem biomass (kg)

Carbon (kg), ×0.47

110

CO₂e (kg), ×44/12

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%.

Inputs	Expected	We get	From
D30 = 20, H = 3	63.8	63.8	Computed from the printed form Computed from the printed Table 5 coefficients; no individual published prediction with all inputs is provided.

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Vachellia tortilis stem biomass (Model 2) · Eshete et al. 2026 · D30
Vachellia tortilis stem biomass (Model 3) · Eshete et al. 2026 · DBH + Height
Vachellia tortilis total aboveground biomass (Model 2) · same paper · Aboveground biomass
Vachellia tortilis total aboveground biomass (Model 3) · same paper · Aboveground biomass
Vachellia tortilis total aboveground biomass (Model 4) · same paper · Aboveground biomass
Vachellia tortilis branch biomass (Model 3) · same paper · Branch biomass
Vachellia tortilis branch biomass (Model 4) · same paper · Branch biomass
Vachellia tortilis branch biomass (Model 5) · same paper · Branch biomass
Vachellia tortilis combined leaf and twig biomass (Model 5) · same paper · Foliage biomass
Vachellia tortilis combined leaf and twig biomass (Model 6) · same paper · Foliage biomass

Compare these curves

Vachellia tortilis stem biomass (Model 4)

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