# C. tabularis AGB from D2H (Model 7, bias-corrected)

Aboveground biomass equation for Chukrasia tabularis, Bangladesh, from Tipu et al. 2021. 98 trees, DBH 9–52 cm. Listed on Tree Allometrics, a free library of tree allometric equations, each quoted from the source that published it.

## Equation

As printed in Tipu et al. 2021 (Results, Allometric models for total aboveground biomass (Model 7, Table 4), p. 208):

> Ln (TAGB) = -3.571 + 1.006 × Ln (D2 × H)

Cite: https://treeallometry.org/equations/tipu-2021-agb-d2h/#equation

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

```
Aboveground biomass = exp(-3.571 + 1.006 * ln(D^2 * H)) * 1.029
```

Inputs: D = Diameter at breast height (1.3 m) (cm); H = Total tree height (m).
The source's own form: exp(-3.571 + 1.006 * ln(DBH^2 * H)) * 1.029, with DBH in cm, H in m; output in kg.
Cite: https://treeallometry.org/equations/tipu-2021-agb-d2h/#canonical

## What it covers

- Output: Aboveground biomass, kg
- Taxon: Chukrasia tabularis (species), family Meliaceae; broadleaf
- Where: Rema-Kalenga Wildlife Sanctuary, Sylhet region, Bangladesh. Cite: https://treeallometry.org/equations/tipu-2021-agb-d2h/#where
- Biomes: tropical
- Stand: natural
- Trees measured: 98. Cite: https://treeallometry.org/equations/tipu-2021-agb-d2h/#n_trees
- DBH range: 9–52 cm. Cite: https://treeallometry.org/equations/tipu-2021-agb-d2h/#dbh
- Height range: 9–37 m. Cite: https://treeallometry.org/equations/tipu-2021-agb-d2h/#height
- R²: 0.96. Cite: https://treeallometry.org/equations/tipu-2021-agb-d2h/#r2
- Residual SE: 0.243. Cite: https://treeallometry.org/equations/tipu-2021-agb-d2h/#rse
- Correction factor: 1.029 (applied). Cite: https://treeallometry.org/equations/tipu-2021-agb-d2h/#cf
- Method: log-log regression (natural log) with Sprugel correction factor; semi-destructive. Cite: https://treeallometry.org/equations/tipu-2021-agb-d2h/#method
- Verification: read in the original source
- Last checked: 2026-11-02. Cite: https://treeallometry.org/equations/tipu-2021-agb-d2h/#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

Tipu, M. T. K., Manzoor Rashid, A. Z. M., Tahasina, C., & Mahmood, H. (2021). Semi-destructive approach in developing allometric biomass for Chukrasia tabularis in Sylhet region of Bangladesh. Journal of Tropical Forest Science, 33(2), 203–212.

- DOI: https://doi.org/10.26525/jtfs2021.33.2.203
- Access: open access
- Copy we read: https://web.archive.org/web/2024/https://info.frim.gov.my/infocenter_applications/jtfsonline/jtfs/v33n2/203-212.pdf
- Every equation from this source: https://treeallometry.org/sources/tipu-2021/
- Cite: https://treeallometry.org/equations/tipu-2021-agb-d2h/#source

## The facts, in the source's words

**Equation** (Results, Allometric models for total aboveground biomass (Model 7, Table 4), p. 208):

> Ln (TAGB) = -3.571 + 1.006 × Ln (D2 × H)

Cite: https://treeallometry.org/equations/tipu-2021-agb-d2h/#equation

**Correction factor** (Table 4, Model 7 row (CF column 1.029)):

> 7 -3.571 1.006 ... 1.029

Cite: https://treeallometry.org/equations/tipu-2021-agb-d2h/#quote-fit-cf

**Trees measured** (Sampling and measurement of sample trees, p. 204):

> In the first event, 98 individuals were chosen to derive the allometric model, covering diameter at breast height and total height range of 9–52 cm and 9–37 m respectively.

Cite: https://treeallometry.org/equations/tipu-2021-agb-d2h/#quote-fit-n-trees

**Smallest DBH** (Discussion, p. 208):

> diameter at breast height (9–52 cm) and total height (9–37 m)

Cite: https://treeallometry.org/equations/tipu-2021-agb-d2h/#quote-fit-dbh-min-cm

**Our note:** Adjusted R2 0.960 and RSE 0.243 as printed for Model 7 in Table 4 (RSE is on the log scale). The paper also prints the final back-transformed form as TAGB = 0.028953 × (D2 × H)^1.006 and a bias-corrected 0.029821 × (D2 × H)^1.006; these two coefficients are not consistent with exp(-3.571) = 0.02813 (0.028953 is close to exp(-3.571) × 1.029, and 0.029821 looks like the correction applied twice). This record uses the printed log-log equation with the printed CF 1.029 (coefficient 0.02894); the paper's 0.029821 form gives about 3% more biomass. Sample was 98 trees for model development (n_trees) plus 22 for validation (120 in total), per the Sampling section, p. 204.

## 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 = 15, H = 15 | 103 | 103 | Computed from the printed form: computed from the published form (exp of the printed log-log equation times the printed CF 1.029) |
| D = 30, H = 22 | 608 | 608 | Computed from the printed form: computed from the published form (exp of the printed log-log equation times the printed CF 1.029) |
| D = 45, H = 30 | 1,878 | 1,878 | Computed from the printed form: computed from the published form (exp of the printed log-log equation times the printed CF 1.029) |

Cite: https://treeallometry.org/equations/tipu-2021-agb-d2h/#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: Tipu, M. T. K., Manzoor Rashid, A. Z. M., Tahasina, C., & Mahmood, H. (2021). Semi-destructive approach in developing allometric biomass for Chukrasia tabularis in Sylhet region of Bangladesh. Journal of Tropical Forest Science, 33(2), 203–212. https://doi.org/10.26525/jtfs2021.33.2.203

Cite this page for the record and checks: Tree Allometrics (Restoration Scope), "C. tabularis AGB from D2H (Model 7, bias-corrected)", checked 2026-11-02, https://treeallometry.org/equations/tipu-2021-agb-d2h/. 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/tipu-2021-agb-d2h.json
Report a problem: email info@restorationscope.com with the equation id (tipu-2021-agb-d2h) and where the right value appears.