# Root biomass from basal area at breast height, all four species

Root biomass equation for Four Sudanian savanna-woodland species (Anogeissus leiocarpa, Detarium microcarpum, Piliostigma thonningii, Vitellaria paradoxa), Burkina Faso, from Koala et al. 2017. 100 trees, DBH 1.59–23.87 cm. Listed on Tree Allometrics, a free library of tree allometric equations, each quoted from the source that published it.

Fitted on Anogeissus leiocarpa, Detarium microcarpum, Piliostigma thonningii, Vitellaria paradoxa.

## Equation

As printed in Koala et al. 2017 (Table 2, BA1.3 row, All species, p. 7):

> BA1.3 1084.9 603.0 0.88 0.09 0.56 0.85 <0.0001

Cite: https://treeallometry.org/equations/koala-2017-bgb-ba13-all-species/#equation

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

```
Root biomass = 1084.9 * (0.7853982 * (D/100)^2)^0.88
```

Inputs: D = Diameter at breast height (1.3 m) (cm).
The source's own form: 1084.9 * (0.7853982 * (DBH/100)^2)^0.88, with DBH in cm; output in kg.
Cite: https://treeallometry.org/equations/koala-2017-bgb-ba13-all-species/#canonical

## What it covers

- Output: Root biomass, kg
- Taxon: Four Sudanian savanna-woodland species (Anogeissus leiocarpa, Detarium microcarpum, Piliostigma thonningii, Vitellaria paradoxa) (mixed species); broadleaf
- Where: Tiogo and Laba state forests, Burkina Faso (north Sudanian savanna-woodland). Cite: https://treeallometry.org/equations/koala-2017-bgb-ba13-all-species/#where
- Biomes: tropical, dryland
- Stand: natural
- Trees measured: 100. Cite: https://treeallometry.org/equations/koala-2017-bgb-ba13-all-species/#n_trees
- DBH range: 1.59–23.87 cm. Cite: https://treeallometry.org/equations/koala-2017-bgb-ba13-all-species/#dbh
- R²: 0.56. Cite: https://treeallometry.org/equations/koala-2017-bgb-ba13-all-species/#r2
- Method: nonlinear regression, BGB = a × BA1.3^b. Cite: https://treeallometry.org/equations/koala-2017-bgb-ba13-all-species/#method
- Verification: read in the original source
- Last checked: 2026-11-01. Cite: https://treeallometry.org/equations/koala-2017-bgb-ba13-all-species/#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

Koala, J., Sawadogo, L., Savadogo, P., Aynekulu, E., Heiskanen, J., Saïd, M. (2017). Allometric equations for below-ground biomass of four key woody species in West African savanna-woodlands. Silva Fennica, 51(3), article 1631.

- DOI: https://doi.org/10.14214/sf.1631
- Access: open access
- Copy we read: https://silvafennica.fi/pdf/1631
- Every equation from this source: https://treeallometry.org/sources/koala-2017/
- Cite: https://treeallometry.org/equations/koala-2017-bgb-ba13-all-species/#source

## The facts, in the source's words

**Equation** (Table 2, BA1.3 row, All species, p. 7):

> BA1.3 1084.9 603.0 0.88 0.09 0.56 0.85 <0.0001

Cite: https://treeallometry.org/equations/koala-2017-bgb-ba13-all-species/#equation

**Equation** (Eq. 4, p. 5):

> BGB = a × BA1.3b + ε

Cite: https://treeallometry.org/equations/koala-2017-bgb-ba13-all-species/#quote-expression

**Units** (Table 2 caption, p. 7):

> basal area (m2) at 1.3 m above ground level (BA1.3)

Cite: https://treeallometry.org/equations/koala-2017-bgb-ba13-all-species/#quote-published-units

**Trees measured** (Table 1, p. 4 (N, then C0.2, C1.3 columns)):

> All species 100 31.9±1.6 8 86 21.6±1.4 5 75

Cite: https://treeallometry.org/equations/koala-2017-bgb-ba13-all-species/#quote-fit-n-trees

**Our note:** Not one of the authors' best models (they recommend basal area at 0.2 m, BA0.2, which has no canonical diameter variable here, and BA×H terms); this is the breast-height-only fit from Table 2, included because it can be used with DBH. Paper input is basal area at 1.3 m in m2; here BA1.3 is computed from DBH as pi*D^2/4 (0.7853982*(D/100)^2) in both forms. Fit dbh range is the printed C1.3 min and max divided by pi (circumference at 1.3 m, Table 1). BGB is stump plus coarse roots (roots over 5 mm for the non-protected species) from excavation, oven-dry. Table 2 prints a and b to 1 or 2 decimals. No correction factor is stated. Only the BA1.3-only models are included: the paper's height columns are labelled cm while the coefficients only make sense with H in metres, so the BA×H and H models are left out. Generic model fitted across the four species. For forked trees the paper's C1.3 is the quadratic sum of stem circumferences (Eq. 1, p. 4), so D here is the equivalent diameter sqrt(ΣDi²).

## 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 = 10 | 15.2 | 15.2 | Computed from the printed form: computed from the published form with BA1.3 = pi*D^2/4 in m2 |

Cite: https://treeallometry.org/equations/koala-2017-bgb-ba13-all-species/#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: Koala, J., Sawadogo, L., Savadogo, P., Aynekulu, E., Heiskanen, J., Saïd, M. (2017). Allometric equations for below-ground biomass of four key woody species in West African savanna-woodlands. Silva Fennica, 51(3), article 1631. https://doi.org/10.14214/sf.1631

Cite this page for the record and checks: Tree Allometrics (Restoration Scope), "Root biomass from basal area at breast height, all four species", checked 2026-11-01, https://treeallometry.org/equations/koala-2017-bgb-ba13-all-species/. 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/koala-2017-bgb-ba13-all-species.json
Report a problem: email info@restorationscope.com with the equation id (koala-2017-bgb-ba13-all-species) and where the right value appears.