# Vietnam evergreen forest AGB with DBH, height and wood density (Eq. 10)

Aboveground biomass equation for Mixed species of tropical evergreen forest (45 species), Vietnam, from Nam et al. 2016. 300 trees, DBH 1.8–115 cm. Listed on Tree Allometrics, a free library of tree allometric equations, each quoted from the source that published it.

## Equation

As printed in Nam et al. 2016 (Eq. 10):

> ln(AGB) = −3.081 + 0.966 ln(DBH²H) + 0.305 ln(WD)

Cite: https://treeallometry.org/equations/nam-2016-eq10/#equation

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

```
Aboveground biomass = 1.030 * exp(-3.081 + 0.966 * ln(D^2 * H) + 0.305 * 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: 1.030 * exp(-3.081 + 0.966 * ln(DBH^2 * H) + 0.305 * ln(WD)), with DBH in cm, H in m, WD in g/cm3; output in kg.
Cite: https://treeallometry.org/equations/nam-2016-eq10/#canonical

## What it covers

- Output: Aboveground biomass, kg
- Taxon: Mixed species of tropical evergreen forest (45 species) (mixed species); broadleaf
- Where: K'Bang district, Gia Lai province, Central Highlands, Vietnam. Cite: https://treeallometry.org/equations/nam-2016-eq10/#where
- Biomes: tropical
- Stand: natural
- Trees measured: 300. Cite: https://treeallometry.org/equations/nam-2016-eq10/#n_trees
- DBH range: 1.8–115 cm. Cite: https://treeallometry.org/equations/nam-2016-eq10/#dbh
- R²: 0.986. Cite: https://treeallometry.org/equations/nam-2016-eq10/#r2
- Residual SE: 0.245. Cite: https://treeallometry.org/equations/nam-2016-eq10/#rse
- Correction factor: 1.03 (applied). Cite: https://treeallometry.org/equations/nam-2016-eq10/#cf
- Method: OLS on ln-transformed data, adjusted R2 (Table 2 model 8). Cite: https://treeallometry.org/equations/nam-2016-eq10/#method
- Verification: read in the original source
- Last checked: 2026-11-01. Cite: https://treeallometry.org/equations/nam-2016-eq10/#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

Nam, V.T., van Kuijk, M., Anten, N.P.R. (2016). Allometric Equations for Aboveground and Belowground Biomass Estimations in an Evergreen Forest in Vietnam. PLoS ONE, 11(6), e0156827.

- DOI: https://doi.org/10.1371/journal.pone.0156827
- Access: open access
- Every equation from this source: https://treeallometry.org/sources/nam-2016/
- Cite: https://treeallometry.org/equations/nam-2016-eq10/#source

## The facts, in the source's words

**Equation** (Eq. 10):

> ln(AGB) = −3.081 + 0.966 ln(DBH²H) + 0.305 ln(WD)

Cite: https://treeallometry.org/equations/nam-2016-eq10/#equation

**Fit** (Table 2, model 8):

> 8 ln(AGB) = a + hln(DBH2H) + cln(WD) 0.986 0.245 -841.2 19.8 1.030

Cite: https://treeallometry.org/equations/nam-2016-eq10/#quote-fit

**Trees measured** (Methods):

> a total of 300 trees pertaining to 45 species

Cite: https://treeallometry.org/equations/nam-2016-eq10/#quote-fit-n-trees

**DBH range** (Table 5):

> AGB = exp(-3.051+0.966ln(DBH2H) +0.305ln(WD)) ... 300 ... 1.8–115.0 ... Vietnam

Cite: https://treeallometry.org/equations/nam-2016-eq10/#quote-fit-dbh

**Our note:** Eq. 10 times the CF 1.030 from Table 2. The paper's Eq. 11 back-transformed form prints 'exp(3,051 + ... + 3.05 ln(WD))', a typo; Table 5 prints exp(-3.051 + 0.966 ln(DBH2H) + 0.305 ln(WD)), i.e. the CF folded into the intercept (ln 1.030 = 0.030). H is the felled stem length. Functional-group models (Eq. 12-15) have no printed CF and are not included.

## 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 = 20, rho = 0.63 | 530 | 530 | Computed from the printed form: hand-computed from the published form |
| D = 60, H = 30, rho = 0.63 | 2,991 | 2,991 | Computed from the printed form: hand-computed from the published form |

Cite: https://treeallometry.org/equations/nam-2016-eq10/#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: Nam, V.T., van Kuijk, M., Anten, N.P.R. (2016). Allometric Equations for Aboveground and Belowground Biomass Estimations in an Evergreen Forest in Vietnam. PLoS ONE, 11(6), e0156827. https://doi.org/10.1371/journal.pone.0156827

Cite this page for the record and checks: Tree Allometrics (Restoration Scope), "Vietnam evergreen forest AGB with DBH, height and wood density (Eq. 10)", checked 2026-11-01, https://treeallometry.org/equations/nam-2016-eq10/. 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/nam-2016-eq10.json
Report a problem: email info@restorationscope.com with the equation id (nam-2016-eq10) and where the right value appears.