# Vachellia tortilis stem biomass (Model 4) Stem biomass equation for Vachellia tortilis, Ethiopia, from Eshete et al. 2026. 15 trees. Listed on Tree Allometrics, a free library of tree allometric equations, each quoted from the source that published it. **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 in Eshete et al. 2026 (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 Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#equation In this library's units, ready to compute (stem biomass in kg): ``` Stem biomass = 0.001 * D30^4.169 * H^(-1.298) ``` Inputs: D30 = Stem diameter at 30 cm (cm); H = Total tree height (m). The source's own form: 0.001 * dsh^4.169 * h^(-1.298), with dsh in cm, h in m; output in kg. Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#canonical ## What it covers - Output: Stem biomass, kg - Taxon: Vachellia tortilis (species); broadleaf - Where: Adami Tullu Jido Kombolcha district, Central Rift Valley, Ethiopia. Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#where - Biomes: dryland - Stand: not stated - Trees measured: 15. Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#n_trees - R²: 0.97. Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#r2 - Method: nonlinear power regression. Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#method - Verification: read in the original source - Last checked: 2026-11-05. Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#checked_at A missing fit statistic is one the source doesn't state, or that we haven't recorded; it is never estimated. Outside the stated DBH range or region, the equation is an extrapolation. ## 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: https://doi.org/10.1007/s44415-026-00110-y - Peer review: A paper in a peer-reviewed journal. - Access: open access - Copy we read: https://link.springer.com/content/pdf/10.1007/s44415-026-00110-y.pdf - Every equation from this source: https://treeallometry.org/sources/eshete-2026/ - Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#source ## The facts, in the source's words **Equation** (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 Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#equation **Equation** (Table 5, Stem Model 4, p. 9): > Model 4 Y = β1dshβ2h β3 0.001 4.169*** − 1.298* 0.97 27.965 − 1.415 22.50 0.77 1 Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#quote-expression **Output** (Table 5, biomass component, p. 9): > Stem Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#quote-output **Units** (Table 5 heading, p. 9): > biomass (kg dry matter/ Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#quote-published-units **Units** (Eq. 1 definition, p. 4): > ith stem at stump or breast height (cm). Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#quote-published-units-2 **Units** (Table 5 note, p. 9): > dsh:stump diameter at 30 cm height; h: total Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#quote-published-units-3 **Units** (Table 5 note, p. 9): > height of plant (m) Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#quote-published-units-4 **Trees measured** (Table 5 note, p. 9): > kg per plant, n: 15 Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#quote-fit-n-trees **R²** (Table 5, Stem Model 4, p. 9): > Model 4 Y = β1dshβ2h β3 0.001 4.169*** − 1.298* 0.97 27.965 − 1.415 22.50 0.77 1 Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#quote-fit-r2 **method** (Abstract, p. 1): > non-linear power function Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#quote-fit-method **Taxon** (Study area, p. 3): > Vachellia tortilis Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#quote-taxon **Where** (Study area, p. 2): > Adami Tullu Jido Kombolcha district Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#quote-region **Where** (Study area, p. 2): > semi-arid climate zone Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#quote-region-2 **Output** (Section 2.2.3, p. 5): > the stem cut-off point was set at a 2.5 cm diameter. Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#quote-output-2 **Our note:** 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. ## Checks this equation passes On every build, the library's form and the source'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. | Cite: https://treeallometry.org/equations/eshete-2026-stem-m4/#checks The calculator on the page shows carbon as biomass × 0.47 (IPCC 2006 Guidelines, Vol. 4, Ch. 4, Table 4.3) and CO₂e as carbon × 44/12. ## How to cite Cite the source for the equation: 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. https://doi.org/10.1007/s44415-026-00110-y Cite this page for the record and checks: Tree Allometrics (Restoration Scope), "Vachellia tortilis stem biomass (Model 4)", checked 2026-11-05, https://treeallometry.org/equations/eshete-2026-stem-m4/. Data CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Quotes are the authors' words. Data for this equation: https://treeallometry.org/data/equations/eshete-2026-stem-m4.json Report a problem: email info@restorationscope.com with the equation id (eshete-2026-stem-m4) and where the right value appears.