# Chinese fir total tree biomass (compatible total-biomass system)

Total biomass equation for Cunninghamia lanceolata, China, from Du et al. 2026. 154 trees, DBH 2.2–35.3 cm. Listed on Tree Allometrics, a free library of tree allometric equations, each quoted from the source that published it.

## Equation

As printed in Du et al. 2026 (Table 8, Eq. 29-31):

> Btotal = 0.065662D 1.750420 H 0.780381 + 0.024760 (D 2 H) 0.774387 (29)

Cite: https://treeallometry.org/equations/du-2026-fir-total/#equation

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

```
Total biomass = 0.065662 * D^1.750420 * H^0.780381 + 0.024760 * (D^2 * H)^0.774387
```

Inputs: D = Diameter at breast height (1.3 m) (cm); H = Total tree height (m).
The source's own form: 0.065662 * D^1.750420 * H^0.780381 + 0.024760 * (D^2 * H)^0.774387, with D in cm, H in m; output in kg.
Cite: https://treeallometry.org/equations/du-2026-fir-total/#canonical

## What it covers

- Output: Total biomass, kg
- Taxon: Cunninghamia lanceolata (species), family Cupressaceae; conifer
- Where: Hunan Province (14 prefecture-level cities and autonomous prefectures). Cite: https://treeallometry.org/equations/du-2026-fir-total/#where
- Biomes: subtropical
- Stand: mixed
- Trees measured: 154. Cite: https://treeallometry.org/equations/du-2026-fir-total/#n_trees
- DBH range: 2.2–35.3 cm. Cite: https://treeallometry.org/equations/du-2026-fir-total/#dbh
- Height range: 2.5–25.6 m. Cite: https://treeallometry.org/equations/du-2026-fir-total/#height
- R²: 0.9208. Cite: https://treeallometry.org/equations/du-2026-fir-total/#r2
- Method: weighted nonlinear least squares. Cite: https://treeallometry.org/equations/du-2026-fir-total/#method
- Verification: read in the original source
- Last checked: 2026-11-02. Cite: https://treeallometry.org/equations/du-2026-fir-total/#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

Du, Z., Liu, Z., Wang, J., Zou, Z., He, W., Zeng, W., Meng, J., & Chen, Z. (2026). Development of Compatible Biomass Models for Chinese Fir, Poplar, and Oak in Hunan Province. Forests, 17(7), 770.

- DOI: https://doi.org/10.3390/f17070770
- Access: open access
- Copy we read: https://www.mdpi.com/1999-4907/17/7/770/pdf?version=1782822414
- Every equation from this source: https://treeallometry.org/sources/du-2026/
- Cite: https://treeallometry.org/equations/du-2026-fir-total/#source

## The facts, in the source's words

**Trees measured** (Section 2.2):

> The sample comprised 154 Chinese fir, 150 poplar, and 157 oak trees.

Cite: https://treeallometry.org/equations/du-2026-fir-total/#quote-fit-n-trees

**Smallest DBH** (Table 1, Chinese fir):

> DBH (cm) 2.2 35.3 19.88 7.77

Cite: https://treeallometry.org/equations/du-2026-fir-total/#quote-fit-dbh-min-cm

**h min m** (Table 1, Chinese fir):

> Tree height (m) 2.5 25.6 14.25 5.38

Cite: https://treeallometry.org/equations/du-2026-fir-total/#quote-fit-h-min-m

**Equation** (Table 8, Eq. 29-31):

> Btotal = 0.065662D 1.750420 H 0.780381 + 0.024760 (D 2 H) 0.774387 (29)

Cite: https://treeallometry.org/equations/du-2026-fir-total/#equation

**Equation** (Table 8 (parameters)):

> (20) 0.065662 1.750420 0.780381 0.024760 0.774387 10.77 7.19 44.54 6.16

Cite: https://treeallometry.org/equations/du-2026-fir-total/#quote-expression

**R²** (Table 11):

> R2 0.9208 (total biomass model, evaluation table)

Cite: https://treeallometry.org/equations/du-2026-fir-total/#quote-fit-r2

**Our note:** Final total-biomass model (aboveground + root). Compatible total-biomass system (aboveground fitted independently, total and root fitted jointly by simultaneous estimation; weighted nonlinear least squares). Total = aboveground + root. The paper lists the sample as stratified random felled trees across eight diameter classes (4-32 cm) from 2022-2023; the reported minimum and maximum DBH and height are for all sampled trees of the species (Table 1). Root biomass was measured on a subset only (whole-root excavation: root collar, coarse roots, fine roots), so root and total fit ranges are not given beyond the full sample. No back-transform factor (nonlinear fit). The paper also gives aboveground-component (stem, crown, wood, bark, branch, foliage) systems (Tables 17-39), not added 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 = 10, H = 9 | 25.3 | 25.3 | Computed from the printed form: hand-computed from the published form |
| D = 30, H = 20 | 311 | 311 | Computed from the printed form: hand-computed from the published form |

Cite: https://treeallometry.org/equations/du-2026-fir-total/#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: Du, Z., Liu, Z., Wang, J., Zou, Z., He, W., Zeng, W., Meng, J., & Chen, Z. (2026). Development of Compatible Biomass Models for Chinese Fir, Poplar, and Oak in Hunan Province. Forests, 17(7), 770. https://doi.org/10.3390/f17070770

Cite this page for the record and checks: Tree Allometrics (Restoration Scope), "Chinese fir total tree biomass (compatible total-biomass system)", checked 2026-11-02, https://treeallometry.org/equations/du-2026-fir-total/. 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/du-2026-fir-total.json
Report a problem: email info@restorationscope.com with the equation id (du-2026-fir-total) and where the right value appears.