# Grevillea robusta on farms, polynomial in DBH (selected model)

Aboveground biomass equation for Grevillea robusta, Kenya, from Owate et al. 2018. 33 trees, DBH 1.5–29.8 cm. Listed on Tree Allometrics, a free library of tree allometric equations, each quoted from the source that published it.

## Equation

As printed in Owate et al. 2018 (Table 7):

> AGB=0.248DBH2 + 6.243DBH – 15.45

Cite: https://treeallometry.org/equations/owate-2018-agb-poly/#equation

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

```
Aboveground biomass = 0.248 * D^2 + 6.243 * D - 15.45
```

Inputs: D = Diameter at breast height (1.3 m) (cm).
The source's own form: 0.248 * DBH^2 + 6.243 * DBH - 15.45, with DBH in cm; output in kg.
Cite: https://treeallometry.org/equations/owate-2018-agb-poly/#canonical

## What it covers

- Output: Aboveground biomass, kg
- Taxon: Grevillea robusta (species), family Proteaceae; broadleaf
- Where: Maragua subcounty, Murang'a County, central Kenya (farms). Cite: https://treeallometry.org/equations/owate-2018-agb-poly/#where
- Biomes: tropical
- Stand: agroforestry
- Trees measured: 33. Cite: https://treeallometry.org/equations/owate-2018-agb-poly/#n_trees
- DBH range: 1.5–29.8 cm. Cite: https://treeallometry.org/equations/owate-2018-agb-poly/#dbh
- Height range: 3.6–24.8 m. Cite: https://treeallometry.org/equations/owate-2018-agb-poly/#height
- R²: 0.94. Cite: https://treeallometry.org/equations/owate-2018-agb-poly/#r2
- Method: polynomial regression on untransformed data. Cite: https://treeallometry.org/equations/owate-2018-agb-poly/#method
- Verification: read in the original source
- Last checked: 2026-11-01. Cite: https://treeallometry.org/equations/owate-2018-agb-poly/#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

Owate, O.A., Mware, M.J., Kinyanjui, M.J. (2018). Allometric Equations for Estimating Silk Oak (Grevillea robusta) Biomass in Agricultural Landscapes of Maragua Subcounty, Kenya. International Journal of Forestry Research, 2018, 6495271.

- DOI: https://doi.org/10.1155/2018/6495271
- Access: open access
- Copy we read: https://onlinelibrary.wiley.com/doi/full/10.1155/2018/6495271
- Every equation from this source: https://treeallometry.org/sources/owate-2018/
- Cite: https://treeallometry.org/equations/owate-2018-agb-poly/#source

## The facts, in the source's words

**Equation** (Table 7):

> AGB=0.248DBH2 + 6.243DBH – 15.45

Cite: https://treeallometry.org/equations/owate-2018-agb-poly/#equation

**Trees measured** (Appendix Table 10 (trees 1-33)):

> 33

Cite: https://treeallometry.org/equations/owate-2018-agb-poly/#quote-fit-n-trees

**Our note:** Selected by the authors. Returns negative AGB below about 2.3 cm DBH, inside the fitted range; use owate-2018-agb-power for trees that small. the authors say the trees do not grow beyond 40 cm DBH and the model should not be applied to larger trees. DBH range from Appendix Table 10.

## 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 = 15 | 134 | 134 | Computed from the printed form: hand-computed from the published form |
| D = 28 | 354 | 354 | Computed from the printed form: hand-computed from the published form |

Cite: https://treeallometry.org/equations/owate-2018-agb-poly/#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: Owate, O.A., Mware, M.J., Kinyanjui, M.J. (2018). Allometric Equations for Estimating Silk Oak (Grevillea robusta) Biomass in Agricultural Landscapes of Maragua Subcounty, Kenya. International Journal of Forestry Research, 2018, 6495271. https://doi.org/10.1155/2018/6495271

Cite this page for the record and checks: Tree Allometrics (Restoration Scope), "Grevillea robusta on farms, polynomial in DBH (selected model)", checked 2026-11-01, https://treeallometry.org/equations/owate-2018-agb-poly/. 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/owate-2018-agb-poly.json
Report a problem: email info@restorationscope.com with the equation id (owate-2018-agb-poly) and where the right value appears.