Equations / Aboveground biomass

Dry forest AGB with height (Model I)

Aboveground biomassTropical broadleaf treesPantropicalnaturalRead from the original paper

Many species, no single photo

Equation

As printed (Choice of the best predictive models, Dry forest stands, p. 92)

⟨AGB⟩est = exp(−2.187 + 0.916 × ln(ρD²H)) ≡ 0.112 × (ρD²H)^0.916

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

Aboveground biomass = exp(-2.187 + 0.916 * ln(rho * D^2 * H))

rho: Wood density (oven-dry mass / green volume), g/cm³
D: Diameter at breast height (1.3 m), cm
H: Total tree height, m

Printed equation already includes the Baskerville correction factor CF = exp(RSE²/2) (paper's Eq. 7); the paper does not print the CF value, so it is not repeated in fit.cf. RSE is the log-scale RSE of the joint fit across forest types (one value per model in the table). The paper writes 'ρ in grams per cubic meter', a misprint for g/cm³ (it defines wood specific gravity in g/cm³ in Methods). Forest types: dry = evapotranspiration exceeds rainfall more than 5 months/yr (roughly <1,500 mm/yr in lowlands); moist = 1–4-month dry season (ca. 1,500–3,500 mm/yr); wet = less than one dry month (>3,500 mm/yr, or montane cloud forest). Minus signs reconstructed from the PDF text layer, where the minus glyph is lost; intercept signs confirmed against Tables 2/4 (a + RSE²/2).

Source

Chave, J., Andalo, C., Brown, S., et al. (2005). Tree allometry and improved estimation of carbon stocks and balance in tropical forests. Oecologia, 145(1), 87–99.

doi:10.1007/s00442-005-0100-x · Paywalled · copy we read

Moist −3.080 – 1.007 – 1,346 0.311 0.996 913

Residual standard error · Table 2, model I.3 row (a, b1, b2, b3, df, RSE, r2, AIC; RSE printed once for the joint dry/moist/wet fit), p. 91

These equations already include the correction factor (Eq. 7).

Note · Choice of the best predictive models, p. 93

The models proposed here are valid in the range 5–156 cm for D, and 50–1,000,000 for ρD²H.

Largest DBH · Recommendations, p. 97

D should be measured in centimeter, H in meter, and ρ in grams per cubic meter. The resulting AGB estimated from the equation is then in kilograms.

Units · Recommendations, p. 97

DBH range: 5–156 cm
Residual SE: 0.311
Method: log-log regression on ρD²H by forest type (model I.3)
Where: 27 harvest sites across the tropics (America, Asia, Oceania); dry forest stands
Last checked: 2026-11-01

Calculate

Wood density (g/cm³)DBH (cm)Height (m)

Height from

682

Aboveground biomass (kg)

320

Carbon (kg), ×0.47

1,175

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, H = 25, rho = 0.6	682	682	Computed from the printed form computed with python3 from the published form

Report a problem with this equation · JSON

Dry forest AGB without height (Model II) · Chave et al. 2005 · Wood density + DBH
Moist forest AGB with height (Model I) · Chave et al. 2005 · Wood density + DBH + Height
Moist forest AGB without height (Model II) · Chave et al. 2005 · Wood density + DBH
Wet forest AGB with height (Model I) · Chave et al. 2005 · Wood density + DBH + Height
Wet forest AGB without height (Model II) · Chave et al. 2005 · Wood density + DBH
Dry forest AGB without height (Model II) · same paper · Aboveground biomass
Moist mangrove AGB without height (Model II) · same paper · Aboveground biomass
Moist forest AGB with height (Model I) · same paper · Aboveground biomass
Moist forest AGB without height (Model II) · same paper · Aboveground biomass
Wet forest AGB with height (Model I) · same paper · Aboveground biomass
Wet forest AGB without height (Model II) · same paper · Aboveground biomass

Compare these curves

Dry forest AGB with height (Model I)

Related