# Canadian national equation, sugar maple, dbh and height (stem wood plus stem bark; Table 4)

Stem biomass equation for Acer saccharum, Canada, from Lambert et al. 2005. 235 trees, DBH 2–57.8 cm. Listed on Tree Allometrics, a free library of tree allometric equations, each quoted from the source that published it.

## Equation

As printed in Lambert et al. 2005 (Eq. 3):

> y wood = β wood1D βwood2Hβwood3 + ewood

Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#equation

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

```
Stem biomass = 0.0301 * D^2.0313 * H^0.8171 + 0.0103 * D^1.7111 * H^0.8509
```

Inputs: D = Diameter at breast height (1.3 m) (cm); H = Total tree height (m).
The source's own form: 0.0301 * dbh^2.0313 * H^0.8171 + 0.0103 * dbh^1.7111 * H^0.8509, with dbh in cm, H in m; output in kg.
Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#canonical

## What it covers

- Output: Stem biomass, kg
- Taxon: Acer saccharum (species), family Sapindaceae; broadleaf
- Where: Ontario and Quebec, Canada (ENFOR archival data, early 1980s). Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#where
- Biomes: temperate
- Stand: not stated
- Trees measured: 235. Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#n_trees
- DBH range: 2–57.8 cm. Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#dbh
- Height range: 2.6–26.4 m. Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#height
- R²: 0.96. Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#r2
- Method: Nonlinear seemingly unrelated regression with weight functions; additivity constrained so compartments sum to total. Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#method
- Verification: read in the original source
- Last checked: 2026-11-03. Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#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

Lambert, M.-C., Ung, C.-H., Raulier, F. (2005). Canadian national tree aboveground biomass equations. Canadian Journal of Forest Research, 35(8), 1996–2018.

- DOI: https://doi.org/10.1139/x05-112
- Access: paywalled
- Copy we read: https://www.esf.edu/quest/documents/Lambertetal.2005.Canadatreebiomass.pdf
- Every equation from this source: https://treeallometry.org/sources/lambert-2005/
- Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#source

## The facts, in the source's words

**Equation** (Eq. 3):

> y wood = β wood1D βwood2Hβwood3 + ewood

Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#equation

**Equation** (Eq. 3):

> y bark = β bark1D βbark2Hβbark3 + e bark

Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#quote-expression

**Equation** (Table 4, Sugar maple):

> Sugar maple bwood1 0.0301

Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#quote-expression-2

**Equation** (Table 4, Sugar maple):

> bwood2 2.0313

Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#quote-expression-3

**Equation** (Table 4, Sugar maple):

> bwood3 0.8171

Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#quote-expression-4

**Equation** (Table 4, Sugar maple):

> bbark1 0.0103

Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#quote-expression-5

**Equation** (Table 4, Sugar maple):

> bbark2 1.7111

Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#quote-expression-6

**Equation** (Table 4, Sugar maple):

> bbark3 0.8509

Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#quote-expression-7

**Trees measured** (Table 2 (No. of trees)):

> Sugar maple            235     24.6±0.9     17.3±0.3     466.9±30.7

Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#quote-fit-n-trees

**Smallest DBH** (Table 2, Sugar maple (ranges of dbh, height, total biomass)):

> (2.0;57.8)   (2.6;26.4)    (1.6;2421.1)

Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#quote-fit-dbh-min-cm

**R²** (Table 5, Sugar maple (AdjRSq in the dbh- and height-based set, second block)):

> Stem 0.1279 0.95 76.6 3.05 0.1327 0.96 69.3 2.95

Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#quote-fit-r2

**Our note:** Stem from ground level to tree top, stem wood plus stem bark; the stem is the sum of the two compartment equations. r2 is the adjusted R² (AdjRSq) of this compartment in Table 5. Fitted on the original scale (weighted nonlinear seemingly unrelated regression), so there is no back-transform correction. Dead branches, cones and fruits are not part of aboveground biomass in this work (Materials). Stand type was not always recorded. Ung, Bernier & Guo (2008) later revised parameters for some species with British Columbia data; not used here.

## 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 = 20, H = 15 | 138 | 138 | Computed from the printed form: computed from the published form at dbh = 20 cm, H = 15 m |

Cite: https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/#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: Lambert, M.-C., Ung, C.-H., Raulier, F. (2005). Canadian national tree aboveground biomass equations. Canadian Journal of Forest Research, 35(8), 1996–2018. https://doi.org/10.1139/x05-112

Cite this page for the record and checks: Tree Allometrics (Restoration Scope), "Canadian national equation, sugar maple, dbh and height (stem wood plus stem bark; Table 4)", checked 2026-11-03, https://treeallometry.org/equations/lambert-2005-sugar-maple-dbh-h-stem/. 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/lambert-2005-sugar-maple-dbh-h-stem.json
Report a problem: email info@restorationscope.com with the equation id (lambert-2005-sugar-maple-dbh-h-stem) and where the right value appears.