# NSVB quaking aspen, Warm Continental Division (210): foliage biomass, Schumacher-Hall model (Eq. 1)

Foliage biomass equation for Populus tremuloides, United States, from Westfall et al. 2024. 188 trees, DBH 2.54–60.45 cm. Listed on Tree Allometrics, a free library of tree allometric equations, each quoted from the source that published it.

## Equation

As printed in Westfall et al. 2024 (Table S9a (Table S9a_foliage_coefs_spcd.csv, WO-GTR-104-Supp1), columns SPCD,DIVISION,STDORGCD,model,a,a1,b,b1,c,c1):

> 746,210,,1,2.720163594,,2.543098465,,-1.098977778,

Cite: https://treeallometry.org/equations/westfall-2024-populus-tremuloides-210-foliage/#equation

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

```
Foliage biomass = 0.45359237 * 2.720163594 * (D/2.54)^2.543098465 * (H/0.3048)^(-1.098977778)
```

Inputs: D = Diameter at breast height (1.3 m) (cm); H = Total tree height (m).
The source's own form: 2.720163594 * DBH^2.543098465 * HT^(-1.098977778), with DBH in in, HT in ft; output in lb.
Cite: https://treeallometry.org/equations/westfall-2024-populus-tremuloides-210-foliage/#canonical

## What it covers

- Output: Foliage biomass, kg
- Taxon: Populus tremuloides (species), family Salicaceae; broadleaf
- Where: FIA ecodivision Warm Continental Division (210), mapped in GTR fig. 1. Cite: https://treeallometry.org/equations/westfall-2024-populus-tremuloides-210-foliage/#where
- Biomes: temperate
- Stand: not stated
- Trees measured: 188. Cite: https://treeallometry.org/equations/westfall-2024-populus-tremuloides-210-foliage/#n_trees
- DBH range: 2.54–60.45 cm. Cite: https://treeallometry.org/equations/westfall-2024-populus-tremuloides-210-foliage/#dbh
- Method: NSVB Schumacher-Hall model (Eq. 1), coefficients for SPCD 746 in DIVISION 210 from table S9a; fitted with weighted regression to destructively sampled trees. Cite: https://treeallometry.org/equations/westfall-2024-populus-tremuloides-210-foliage/#method
- Verification: read in the original source
- Last checked: 2026-11-03. Cite: https://treeallometry.org/equations/westfall-2024-populus-tremuloides-210-foliage/#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

Westfall, J.A., Coulston, J.W., Gray, A.N., Shaw, J.D., Radtke, P.J., Walker, D.M., Weiskittel, A.R., et al. (2024). A national-scale tree volume, biomass, and carbon modeling system for the United States. Gen. Tech. Rep. WO-104. Washington, DC: USDA Forest Service. 37 p.

- DOI: https://doi.org/10.2737/WO-GTR-104
- Access: open access
- Copy we read: https://research.fs.usda.gov/download/treesearch/66998.pdf
- Every equation from this source: https://treeallometry.org/sources/westfall-2024/
- Cite: https://treeallometry.org/equations/westfall-2024-populus-tremuloides-210-foliage/#source

## The facts, in the source's words

**Equation** (Table S9a (Table S9a_foliage_coefs_spcd.csv, WO-GTR-104-Supp1), columns SPCD,DIVISION,STDORGCD,model,a,a1,b,b1,c,c1):

> 746,210,,1,2.720163594,,2.543098465,,-1.098977778,

Cite: https://treeallometry.org/equations/westfall-2024-populus-tremuloides-210-foliage/#equation

**Equation** (Eq. 1, p. 2):

> yi = a × Di^b × Hi^c + εi

Cite: https://treeallometry.org/equations/westfall-2024-populus-tremuloides-210-foliage/#quote-expression

**Units** (Methods, Model development, p. 2):

> Di is diameter (inches) at breast height (4.5 feet), Hi is total tree height (feet)

Cite: https://treeallometry.org/equations/westfall-2024-populus-tremuloides-210-foliage/#quote-published-units

**published.output unit** (Examples of tree-level calculations, p. 8):

> units for volume and biomass predictions are cubic feet and pounds, respectively

Cite: https://treeallometry.org/equations/westfall-2024-populus-tremuloides-210-foliage/#quote-published-output-unit

**Taxon** (FIADB REF_SPECIES.csv (FIA DataMart), columns SPCD,COMMON_NAME,SHARED_COMMON_NAME_IND,GENUS,SPECIES,VARIETY,SUBSPECIES,SCIENTIFIC_NAME: the species codes the NSVB tables use):

> 746,quaking aspen,N,Populus,tremuloides,,,Populus tremuloides

Cite: https://treeallometry.org/equations/westfall-2024-populus-tremuloides-210-foliage/#quote-taxon

**Fit** (Table S19_component_division_spcd_scorecard.csv (WO-GTR-104-Supp1), columns VAR2,VAR3,SPCD,DIVISION,DIVISION_DESCRIPTION,N,Avg_DBH,Min_DBH,Max_DBH):

> "Foliage","FOL_DW","746","210","WARM_CONTINENTAL_DIVISION",188,7.2218085106383,1,23.8

Cite: https://treeallometry.org/equations/westfall-2024-populus-tremuloides-210-foliage/#quote-fit

**Fit** (Methods, Model development, p. 6):

> key modeling statistics such as sample sizes (n), tree diameter distributions (minimum, mean, and maximum)

Cite: https://treeallometry.org/equations/westfall-2024-populus-tremuloides-210-foliage/#quote-fit-2

**Our note:** DBH is measured at 4.5 ft (1.37 m). Paper units: in, ft, lb; expression converts D cm→in (/2.54), H m→ft (/0.3048) and lb→kg (×0.45359237). n and the DBH range are from the scorecard for FOL_DW in 210 (table S19).

## 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 = 30.48, H = 21.336 | 6.43 | 6.43 | Computed from the printed form: computed from the published form at D = 12 in, H = 70 ft, converted to cm, m and kg |

Cite: https://treeallometry.org/equations/westfall-2024-populus-tremuloides-210-foliage/#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: Westfall, J.A., Coulston, J.W., Gray, A.N., Shaw, J.D., Radtke, P.J., Walker, D.M., Weiskittel, A.R., et al. (2024). A national-scale tree volume, biomass, and carbon modeling system for the United States. Gen. Tech. Rep. WO-104. Washington, DC: USDA Forest Service. 37 p. https://doi.org/10.2737/WO-GTR-104

Cite this page for the record and checks: Tree Allometrics (Restoration Scope), "NSVB quaking aspen, Warm Continental Division (210): foliage biomass, Schumacher-Hall model (Eq. 1)", checked 2026-11-03, https://treeallometry.org/equations/westfall-2024-populus-tremuloides-210-foliage/. 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/westfall-2024-populus-tremuloides-210-foliage.json
Report a problem: email info@restorationscope.com with the equation id (westfall-2024-populus-tremuloides-210-foliage) and where the right value appears.