# Western hemlock total aboveground biomass from DBH and height (Table 4)

Aboveground biomass equation for Tsuga heterophylla, United States, from Poudel et al. 2019. 115 trees, DBH 3.1–77.8 cm. Listed on Tree Allometrics, a free library of tree allometric equations, each quoted from the source that published it.

## Equation

As printed in Poudel et al. 2019 (Table 4, species row and table note):

> Western hemlock  a, b, c, d, CF: −2.7552  1.8521  0.7642  CF 1.0209; model form exp(a + bX1 + cX2)

Cite: https://treeallometry.org/equations/poudel-2019-tsuga-heterophylla/#equation

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

```
Aboveground biomass = 1.0209 * exp(-2.7552 + 1.8521 * ln(D) + 0.7642 * ln(H))
```

Inputs: D = Diameter at breast height (1.3 m) (cm); H = Total tree height (m).
The source's own form: 1.0209 * exp(-2.7552 + 1.8521 * ln(DBH) + 0.7642 * ln(HT)), with DBH in cm, HT in m; output in kg.
Cite: https://treeallometry.org/equations/poudel-2019-tsuga-heterophylla/#canonical

## What it covers

- Output: Aboveground biomass, kg
- Taxon: Tsuga heterophylla (species), family Pinaceae; conifer
- Where: Western U.S.A., legacy destructive-sampling biomass collection (Radtke et al. 2015). Cite: https://treeallometry.org/equations/poudel-2019-tsuga-heterophylla/#where
- Biomes: temperate
- Stand: mixed
- Trees measured: 115. Cite: https://treeallometry.org/equations/poudel-2019-tsuga-heterophylla/#n_trees
- DBH range: 3.1–77.8 cm. Cite: https://treeallometry.org/equations/poudel-2019-tsuga-heterophylla/#dbh
- Height range: 3.5–53 m. Cite: https://treeallometry.org/equations/poudel-2019-tsuga-heterophylla/#height
- Correction factor: 1.0209 (applied). Cite: https://treeallometry.org/equations/poudel-2019-tsuga-heterophylla/#cf
- Method: regression on ln(AGB) with Baskerville log-bias correction factor. Cite: https://treeallometry.org/equations/poudel-2019-tsuga-heterophylla/#method
- Verification: read in the original source
- Last checked: 2026-11-02. Cite: https://treeallometry.org/equations/poudel-2019-tsuga-heterophylla/#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

Poudel, K. P., Temesgen, H., Radtke, P. J., & Gray, A. N. (2019). Estimating individual-tree aboveground biomass of tree species in the western U.S.A. Canadian Journal of Forest Research, 49(6), 701-714.

- DOI: https://doi.org/10.1139/cjfr-2018-0361
- Access: open access
- Copy we read: https://vtechworks.lib.vt.edu/bitstreams/13666b54-8fb3-444c-8f8f-f54bc602a4b9/download
- Every equation from this source: https://treeallometry.org/sources/poudel-2019/
- Cite: https://treeallometry.org/equations/poudel-2019-tsuga-heterophylla/#source

## The facts, in the source's words

**Equation** (Table 4, species row and table note):

> Western hemlock  a, b, c, d, CF: −2.7552  1.8521  0.7642  CF 1.0209; model form exp(a + bX1 + cX2)

Cite: https://treeallometry.org/equations/poudel-2019-tsuga-heterophylla/#equation

**Trees measured** (Table 1):

> Western hemlock ... n 115

Cite: https://treeallometry.org/equations/poudel-2019-tsuga-heterophylla/#quote-fit-n-trees

**Smallest DBH** (Table 1):

> Western hemlock DBH min 3.1 max 77.8; HT min 3.5 max 53.0

Cite: https://treeallometry.org/equations/poudel-2019-tsuga-heterophylla/#quote-fit-dbh-min-cm

**Our note:** AGB is total aboveground live-tree biomass (stem, bark, branches, foliage). X1 = ln(DBH), X2 = ln(HT), DBH in cm and HT in m. Species identified from the common name in Table 4 (scientific name added from the standard species symbol). Stand type is not stated. Observed ranges in Table 1 cover all trees of the species used.

## 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 | 132 | 132 | Computed from the printed form: computed from the Table 4 coefficients |
| D = 40, H = 25 | 705 | 705 | Computed from the printed form: computed from the Table 4 coefficients |

Cite: https://treeallometry.org/equations/poudel-2019-tsuga-heterophylla/#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: Poudel, K. P., Temesgen, H., Radtke, P. J., & Gray, A. N. (2019). Estimating individual-tree aboveground biomass of tree species in the western U.S.A. Canadian Journal of Forest Research, 49(6), 701-714. https://doi.org/10.1139/cjfr-2018-0361

Cite this page for the record and checks: Tree Allometrics (Restoration Scope), "Western hemlock total aboveground biomass from DBH and height (Table 4)", checked 2026-11-02, https://treeallometry.org/equations/poudel-2019-tsuga-heterophylla/. 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/poudel-2019-tsuga-heterophylla.json
Report a problem: email info@restorationscope.com with the equation id (poudel-2019-tsuga-heterophylla) and where the right value appears.