# Campo-Ma'an AGB from DBH, height and wood density (Table 3, model 5)

Aboveground biomass equation for Mixed species, Campo-Ma'an lowland moist forest, Cameroon, from Djomo et al. 2010. 71 trees, DBH 1–79 cm. Listed on Tree Allometrics, a free library of tree allometric equations, each quoted from the source that published it.

## Equation

As printed in Djomo et al. 2010 (Table 3, Total biomass, model 5 and footnote a):

> 5. ln(M) = a + b(ln D)2 + c ln(D2 H) + β ln(ρ)   a = −2.3325  b = 0.1651  c = 0.6620  (β = 0.1309)

Cite: https://treeallometry.org/equations/djomo-2010-campo-d-d2h-rho/#equation

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

```
Aboveground biomass = exp(-2.3325 + 0.1651 * ln(D)^2 + 0.6620 * ln(D^2 * H) + 0.1309 * ln(rho))
```

Inputs: D = Diameter at breast height (1.3 m) (cm); H = Total tree height (m); rho = Wood density (oven-dry mass / green volume) (g/cm³).
The source's own form: exp(-2.3325 + 0.1651 * ln(D)^2 + 0.6620 * ln(D^2 * H) + 0.1309 * ln(WD)), with D in cm, H in m, WD in g/cm3; output in kg.
Cite: https://treeallometry.org/equations/djomo-2010-campo-d-d2h-rho/#canonical

## What it covers

- Output: Aboveground biomass, kg
- Taxon: Mixed species, Campo-Ma'an lowland moist forest (mixed species); broadleaf
- Where: Campo-Ma'an, southern Cameroon. Cite: https://treeallometry.org/equations/djomo-2010-campo-d-d2h-rho/#where
- Biomes: tropical
- Stand: natural
- Trees measured: 71. Cite: https://treeallometry.org/equations/djomo-2010-campo-d-d2h-rho/#n_trees
- DBH range: 1–79 cm. Cite: https://treeallometry.org/equations/djomo-2010-campo-d-d2h-rho/#dbh
- R²: 0.9659. Cite: https://treeallometry.org/equations/djomo-2010-campo-d-d2h-rho/#r2
- Residual SE: 0.291. Cite: https://treeallometry.org/equations/djomo-2010-campo-d-d2h-rho/#rse
- Method: log-log regression. Cite: https://treeallometry.org/equations/djomo-2010-campo-d-d2h-rho/#method
- Verification: read in the original source
- Last checked: 2026-11-01. Cite: https://treeallometry.org/equations/djomo-2010-campo-d-d2h-rho/#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

Djomo, A.N., Ibrahima, A., Saborowski, J., Gravenhorst, G. (2010). Allometric equations for biomass estimations in Cameroon and pan moist tropical equations including biomass data from Africa. Forest Ecology and Management, 260(10), 1873–1885.

- DOI: https://doi.org/10.1016/j.foreco.2010.08.034
- Access: paywalled
- Copy we read: https://uni-goettingen.de/de/document/download/4df40c701547ab5773871feade802dc2.pdf/Djomo_et_al_(2010)_FORECOLMANAG_allometric_equations.pdf
- Every equation from this source: https://treeallometry.org/sources/djomo-2010/
- Cite: https://treeallometry.org/equations/djomo-2010-campo-d-d2h-rho/#source

## The facts, in the source's words

**Equation** (Table 3, Total biomass, model 5 and footnote a):

> 5. ln(M) = a + b(ln D)2 + c ln(D2 H) + β ln(ρ)   a = −2.3325  b = 0.1651  c = 0.6620  (β = 0.1309)

Cite: https://treeallometry.org/equations/djomo-2010-campo-d-d2h-rho/#equation

**Trees measured** (Table 3, model 5):

> N 71, RSE 0.291, Adj. R2 0.9659, D (cm) 1–79

Cite: https://treeallometry.org/equations/djomo-2010-campo-d-d2h-rho/#quote-fit-n-trees

**Our note:** Best-fitting site equation (lowest RSE, average error 3.4%). Printed form has the intermediate coefficient for ln(D²H) as c and β for ln(ρ) from the table footnote. Coefficients are used as printed; the paper does not state that the log-scale back-transformation correction factor is included, so none is applied. Reported R² is the adjusted R². Table 3 fit on 71 trees (7 of its equations captured). The Discussion (p. 1880) refits on 91 trees and recommends slightly different coefficients, printed without n, RSE or R²; this file keeps the Table 3 fit. The paper notes only three of the 71 trees were above 10 cm. The text calls the best three-variable fit 'model 14' (with a (ln D)³ term), but Table 3 model 5, the only place coefficients are printed, has none; this file follows Table 3.

## 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 = 0.64 | 470 | 470 | Computed from the printed form: hand-computed from the published form |

Cite: https://treeallometry.org/equations/djomo-2010-campo-d-d2h-rho/#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: Djomo, A.N., Ibrahima, A., Saborowski, J., Gravenhorst, G. (2010). Allometric equations for biomass estimations in Cameroon and pan moist tropical equations including biomass data from Africa. Forest Ecology and Management, 260(10), 1873–1885. https://doi.org/10.1016/j.foreco.2010.08.034

Cite this page for the record and checks: Tree Allometrics (Restoration Scope), "Campo-Ma'an AGB from DBH, height and wood density (Table 3, model 5)", checked 2026-11-01, https://treeallometry.org/equations/djomo-2010-campo-d-d2h-rho/. 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/djomo-2010-campo-d-d2h-rho.json
Report a problem: email info@restorationscope.com with the equation id (djomo-2010-campo-d-d2h-rho) and where the right value appears.