# North American taxa group: woodland Fagaceae (Table 5)

Aboveground biomass equation for Woodland Fagaceae (Quercus douglasii, Q. gambelii, Q. hypoleucoides, Quercus (live) spp.), United States, from Chojnacky et al. 2014. Listed on Tree Allometrics, a free library of tree allometric equations, each quoted from the source that published it.

Fitted on Quercus douglasii, Quercus gambelii, Quercus hypoleucoides, and other species the source does not name here.

## Equation

As printed in Chojnacky et al. 2014 (Table 5 caption, p. 140):

> ln(biomass) = β0 + β1 ln(diameter)

Cite: https://treeallometry.org/equations/chojnacky-2014-woodland-fagaceae/#equation

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

```
Aboveground biomass = exp(-3.0304 + 2.4982 * ln(DRC))
```

Inputs: DRC = Root collar / stem base diameter (cm).
The source's own form: exp(-3.0304 + 2.4982 * ln(drc)), with drc in cm; output in kg.
Cite: https://treeallometry.org/equations/chojnacky-2014-woodland-fagaceae/#canonical

## What it covers

- Output: Aboveground biomass, kg
- Taxon: Woodland Fagaceae (Quercus douglasii, Q. gambelii, Q. hypoleucoides, Quercus (live) spp.) (mixed species), family Fagaceae; broadleaf
- Where: United States (equations compiled from US and Canadian studies). Cite: https://treeallometry.org/equations/chojnacky-2014-woodland-fagaceae/#where
- Biomes: temperate, dryland
- Stand: mixed
- R²: 0.84. Cite: https://treeallometry.org/equations/chojnacky-2014-woodland-fagaceae/#r2
- Method: Weighted regression of ln(biomass) on ln(drc) fitted to 36 pseudodata points generated from 5 published equations; no back-transform correction. Cite: https://treeallometry.org/equations/chojnacky-2014-woodland-fagaceae/#method
- Verification: read in the original source
- Last checked: 2026-11-03. Cite: https://treeallometry.org/equations/chojnacky-2014-woodland-fagaceae/#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

Chojnacky, D.C., Heath, L.S., Jenkins, J.C. (2014). Updated generalized biomass equations for North American tree species. Forestry, 87(1), 129–151.

- DOI: https://doi.org/10.1093/forestry/cpt053
- Access: open access
- Copy we read: https://research.fs.usda.gov/download/treesearch/45402.pdf
- Every equation from this source: https://treeallometry.org/sources/chojnacky-2014/
- Cite: https://treeallometry.org/equations/chojnacky-2014-woodland-fagaceae/#source

## The facts, in the source's words

**Equation** (Table 5 caption, p. 140):

> ln(biomass) = β0 + β1 ln(diameter)

Cite: https://treeallometry.org/equations/chojnacky-2014-woodland-fagaceae/#equation

**Equation** (Table 5 row, p. 140):

> Fagaceae 0.59 −3.0304 2.4982 36 5 drc 3–74 0.84

Cite: https://treeallometry.org/equations/chojnacky-2014-woodland-fagaceae/#quote-expression

**Taxon** (Table 4, p. 138):

> Fagaceae Q. gambelii Oak, Gambel 814 0.61 2

Cite: https://treeallometry.org/equations/chojnacky-2014-woodland-fagaceae/#quote-taxon

**Correction factor** (Methods, p. 139):

> we did not include a correction (Baskerville, 1972) for underestimation

Cite: https://treeallometry.org/equations/chojnacky-2014-woodland-fagaceae/#quote-fit-cf

**Our note:** Woodland oaks (blue, Gambel, silverleaf and evergreen live oaks), by root-collar diameter. Root-collar diameter range of the pseudodata: 3–74 cm. Median specific gravity of the group: 0.59. R² is the published 'R²-statistic'.

## 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 |
| --- | --- | --- | --- |
| DRC = 30 | 237 | 237 | Computed from the printed form: computed from the published form at drc = 30 cm |

Cite: https://treeallometry.org/equations/chojnacky-2014-woodland-fagaceae/#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: Chojnacky, D.C., Heath, L.S., Jenkins, J.C. (2014). Updated generalized biomass equations for North American tree species. Forestry, 87(1), 129–151. https://doi.org/10.1093/forestry/cpt053

Cite this page for the record and checks: Tree Allometrics (Restoration Scope), "North American taxa group: woodland Fagaceae (Table 5)", checked 2026-11-03, https://treeallometry.org/equations/chojnacky-2014-woodland-fagaceae/. 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/chojnacky-2014-woodland-fagaceae.json
Report a problem: email info@restorationscope.com with the equation id (chojnacky-2014-woodland-fagaceae) and where the right value appears.