{"id":"eshete-2026-agb-m4","source":{"id":"eshete-2026","citation":"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.","title":"Aboveground biomass estimation of Vachellia tortilis (Forssk. Galasso & Banfi) for sustainable bioenergy production in the Central Rift Valley, Ethiopia","authors":["Eshete, A.","Getnet, D.","Yilma, Z.","Chimsa, D.","Befikadu, E."],"year":2026,"type":"journal-article","venue":"Discover Forests","doi":"10.1007/s44415-026-00110-y","url":"https://doi.org/10.1007/s44415-026-00110-y","read_url":"https://link.springer.com/content/pdf/10.1007/s44415-026-00110-y.pdf","access":"open","license":"CC BY-NC-ND 4.0","checked_at":"2026-11-05","status":"current"},"name":"Vachellia tortilis total aboveground biomass (Model 4)","output":{"quantity":"agb"},"expression":"0.31 * D30^1.731 * H^0.633","published":{"expression":"0.31 * dsh^1.731 * h^0.633","units":{"dsh":"cm","h":"m"},"variables":{"dsh":"D30","h":"H"},"output_unit":"kg"},"taxon":{"level":"species","name":"Vachellia tortilis","group":"broadleaf"},"region":{"scope":"site","countries":["ET"],"place":"Adami Tullu Jido Kombolcha district, Central Rift Valley, Ethiopia","biomes":["dryland"]},"fit":{"n_trees":15,"r2":0.97,"method":"nonlinear power regression"},"evidence":[{"field":"expression","quote":"Y = 0.31dₛₕ^1.731 h^0.633","locator":"Fig. 4 caption, full equation for M₄, p. 11; corresponding fit in Table 5, Total Model 4 row, p. 9"},{"field":"expression","quote":"Model 4                 Y = β1dshβ2h β3   0.31 1.731***       0.633** 0.97 36.55           0.605 29.558 0.90 1","locator":"Table 5, Total Model 4, p. 9"},{"field":"output","quote":"Total","locator":"Table 5, biomass component, p. 9"},{"field":"published.units","quote":"biomass (kg dry matter/","locator":"Table 5 heading, p. 9"},{"field":"published.units","quote":"ith stem at stump or breast height (cm).","locator":"Eq. 1 definition, p. 4"},{"field":"published.units","quote":"d: diameter at breast height (1.30 m); dsh:stump diameter at 30 cm height; h: total","locator":"Table 5 note, p. 9"},{"field":"published.units","quote":"height of plant (m)","locator":"Table 5 note, p. 9"},{"field":"fit.n_trees","quote":"kg per plant, n: 15","locator":"Table 5 note, p. 9"},{"field":"fit.r2","quote":"Model 4                 Y = β1dshβ2h β3   0.31 1.731***       0.633** 0.97 36.55           0.605 29.558 0.90 1","locator":"Table 5, Total Model 4, p. 9"},{"field":"fit.method","quote":"non-linear power function","locator":"Abstract, p. 1"},{"field":"taxon","quote":"Vachellia tortilis","locator":"Study area, p. 3"},{"field":"region","quote":"Adami Tullu Jido Kombolcha district","locator":"Study area, p. 2"},{"field":"region","quote":"semi-arid climate zone","locator":"Study area, p. 2"}],"check":[{"inputs":{"D30":20,"H":3},"expected":111.035632,"origin":"computed","note":"Computed from the printed Table 5 coefficients; no individual published prediction with all inputs is provided."}],"verification":"original_read","doubt":"Section 2.3.3 says M4 requires only stump diameter, whereas Tables 1, 5 and 6 and Fig. 4 include total height. This record uses the explicitly parameterized equation in Table 5; confirm the conflicting description with the authors before relying on it.","checked_at":"2026-11-05","notes":"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 the relevant height (Eq. 1). The harvested stump-diameter range was 3.2–44.5 cm. The authors recommend M4 for precise carbon accounting."}