{"id":"nath-2019-model1","source":{"id":"nath-2019","citation":"Nath, A.J., Tiwari, B.K., Sileshi, G.W., et al. (2019). Allometric Models for Estimation of Forest Biomass in North East India. Forests, 10(2), 103.","title":"Allometric Models for Estimation of Forest Biomass in North East India","authors":["Nath, A.J.","Tiwari, B.K.","Sileshi, G.W."],"year":2019,"venue":"Forests","doi":"10.3390/f10020103","url":"https://doi.org/10.3390/f10020103","read_url":"https://www.mdpi.com/1999-4907/10/2/103/htm","access":"open","license":"CC BY 4.0","checked_at":"2026-11-02","status":"current"},"name":"NE India mixed-forest AGB from DBH, power law (Model 1, second best)","output":{"quantity":"agb"},"expression":"0.18 * D^2.16 * 1.32","published":{"expression":"0.18 * D^2.16 * 1.32","units":{"D":"cm"},"output_unit":"kg"},"taxon":{"level":"mixed","name":"Dominant tree species of four NE Indian forest types","group":"mixed"},"region":{"scope":"regional","countries":["IN"],"place":"North East India (tropical semi-evergreen, tropical wet evergreen, sub-tropical broad leaved and sub-tropical pine forest)","biomes":["tropical","subtropical","montane"]},"stand":"natural","fit":{"n_trees":303,"dbh_min_cm":10.1,"dbh_max_cm":90,"r2":0.705,"cf":1.32,"method":"Linear mixed model on log scale (forest type random effect), back-transformed with CF = exp(MSE/2)"},"evidence":[{"field":"expression","quote":"AGBest = 0.18D2.16 × 1.32","locator":"Abstract"},{"field":"fit.n_trees","quote":"Sample tree data (a total of 303 trees) were collected from four major forest types","locator":"Section 2.2"},{"field":"fit.dbh_min_cm","quote":"seven diameter classes were formed: 10.1–20 cm, 20.1–30 cm, 30.1–40 cm, 40.1–50 cm, 50.1–60 cm, 60.1–70 cm, and 70.1–90 cm","locator":"Section 2.2"},{"field":"fit.cf","quote":"Upon back transformation, each model was multiplied with a correction factor (CF) estimated from the residual variance or mean square error (MSE) using the formula CF = exp(MSE/2)","locator":"Section 2.3"},{"field":"published.units","quote":"AGB is total above-ground biomass in kg dry matter tree−1, ... D is diameter at breast height in centimeters","locator":"Section 2.3"},{"field":"fit.r2","quote":"1 ... LME −1.73 (0.45) 2.16 (0.10) - 705 0.705 0.749","locator":"Table 2, Model 1 LME row (Adj R2 column)"}],"check":[{"inputs":{"D":30},"expected":368.4922,"origin":"computed","note":"computed from the published form in the Abstract"}],"verification":"original_read","checked_at":"2026-11-02","notes":"Coefficients as printed in the Abstract and Results (two decimals). Table 2 (LME, Model 1) prints ln(a) = −1.73 (SE 0.45) and b = 2.16 (SE 0.10); exp(−1.73) = 0.177, consistent with the printed 0.18, and the Model 1 residual variance 0.56 (Table 3) gives CF = exp(0.56/2) = 1.32. r2 is the adjusted R2 of the LME fit as printed in Table 2 (R2 = 1 − RVm/RVi for the mixed model). The 1.32 correction factor is part of the printed equation. Model 3 (0.32(D²Hδ)^0.75 × 1.34, the authors' best) was not added: the text gives wood density in kg m-3 but the printed form only gives plausible biomass with g/cm3, so the unit is unclear. DBH range is the sampling-class span, not a stated fitted range."}