Equations / Aboveground biomass

NE India mixed-forest AGB from DBH, power law (Model 1, second best)

Aboveground biomassDominant tree species of four NE Indian forest typesIndianaturalRead from the original paper

Many species, no single photo

Equation

As printed (Abstract)

AGBest = 0.18D2.16 × 1.32

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

Aboveground biomass = 0.18 * D^2.16 * 1.32

D: Diameter at breast height (1.3 m), cm

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.

Source

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.

doi:10.3390/f10020103 · Open access · copy we read

Sample tree data (a total of 303 trees) were collected from four major forest types

Trees measured · Section 2.2

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

Smallest DBH · Section 2.2

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)

Correction factor · Section 2.3

AGB is total above-ground biomass in kg dry matter tree−1, ... D is diameter at breast height in centimeters

Units · Section 2.3

1 ... LME −1.73 (0.45) 2.16 (0.10) - 705 0.705 0.749

R² · Table 2, Model 1 LME row (Adj R2 column)

Trees measured: 303
DBH range: 10.1–90 cm
R²: 0.705
Correction factor: 1.32 (applied)
Method: Linear mixed model on log scale (forest type random effect), back-transformed with CF = exp(MSE/2)
Where: North East India (tropical semi-evergreen, tropical wet evergreen, sub-tropical broad leaved and sub-tropical pine forest)
Last checked: 2026-11-02

Calculate

DBH (cm)

368.5

Aboveground biomass (kg)

173.2

Carbon (kg), ×0.47

635

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%.

Inputs	Expected	We get	From
D = 30	368.5	368.5	Computed from the printed form computed from the published form in the Abstract

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