# Dry forest AGB with height (Model I)

Aboveground biomass equation for Tropical broadleaf trees, Pantropical, from Chave et al. 2005. DBH 5–156 cm. Listed on Tree Allometrics, a free library of tree allometric equations, each quoted from the source that published it.

## Equation

As printed in Chave et al. 2005 (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

Cite: https://treeallometry.org/equations/chave-2005-dry-h/#equation

In this library's units, ready to compute (aboveground biomass in kg):

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

Inputs: rho = Wood density (oven-dry mass / green volume) (g/cm³); D = Diameter at breast height (1.3 m) (cm); H = Total tree height (m).
The source's own form: exp(-2.187 + 0.916 * ln(rho * D^2 * H)), with D in cm, rho in g/cm3, H in m; output in kg.
Cite: https://treeallometry.org/equations/chave-2005-dry-h/#canonical

## What it covers

- Output: Aboveground biomass, kg
- Taxon: Tropical broadleaf trees (mixed species); broadleaf
- Where: 27 harvest sites across the tropics (America, Asia, Oceania); dry forest stands. Cite: https://treeallometry.org/equations/chave-2005-dry-h/#where
- Biomes: tropical, dryland
- Stand: natural
- DBH range: 5–156 cm. Cite: https://treeallometry.org/equations/chave-2005-dry-h/#dbh
- Residual SE: 0.311. Cite: https://treeallometry.org/equations/chave-2005-dry-h/#rse
- Method: log-log regression on ρD²H by forest type (model I.3). Cite: https://treeallometry.org/equations/chave-2005-dry-h/#method
- Verification: read in the original source
- Last checked: 2026-11-01. Cite: https://treeallometry.org/equations/chave-2005-dry-h/#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

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: https://doi.org/10.1007/s00442-005-0100-x
- Access: paywalled
- Copy we read: https://web.archive.org/web/2024id_/https://pdf.usaid.gov/pdf_docs/PA00KWXN.pdf
- Every equation from this source: https://treeallometry.org/sources/chave-2005/
- Cite: https://treeallometry.org/equations/chave-2005-dry-h/#source

## The facts, in the source's words

**Equation** (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

Cite: https://treeallometry.org/equations/chave-2005-dry-h/#equation

**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):

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

Cite: https://treeallometry.org/equations/chave-2005-dry-h/#quote-fit-rse

**Note** (Choice of the best predictive models, p. 93):

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

Cite: https://treeallometry.org/equations/chave-2005-dry-h/#quote-notes

**Largest DBH** (Recommendations, p. 97):

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

Cite: https://treeallometry.org/equations/chave-2005-dry-h/#quote-fit-dbh-max-cm

**Units** (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.

Cite: https://treeallometry.org/equations/chave-2005-dry-h/#quote-published-units

**Our note:** 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).

## 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 |
| --- | --- | --- | --- |
| D = 30, H = 25, rho = 0.6 | 681.7 | 681.7 | Computed from the printed form: computed with python3 from the published form |

Cite: https://treeallometry.org/equations/chave-2005-dry-h/#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: 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. https://doi.org/10.1007/s00442-005-0100-x

Cite this page for the record and checks: Tree Allometrics (Restoration Scope), "Dry forest AGB with height (Model I)", checked 2026-11-01, https://treeallometry.org/equations/chave-2005-dry-h/. 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/chave-2005-dry-h.json
Report a problem: email info@restorationscope.com with the equation id (chave-2005-dry-h) and where the right value appears.