# Peat swamp forest, non-Dipterocarpaceae group, volume from D (model 1)

Stem volume equation for Non-dipterocarp species group (P. rostratum, C. soulattri, D. pectinatum, as printed), Indonesia, from Qirom & Akbar 2020. 42 trees, DBH 5.6–27 cm. Listed on Tree Allometrics, a free library of tree allometric equations, each quoted from the source that published it.

## Equation

As printed in Qirom & Akbar 2020 (Best model, non-Dipterocarpaceae group, p. 10 (Tabel 3 model 1)):

> ln (V ) = -8.398596 + 2.4688 ln (D ) ... R2 97,3 %

Cite: https://treeallometry.org/equations/qirom-2020-non-dipterocarpaceae-ln-d/#equation

In this library's units, ready to compute (stem volume in m³):

```
Stem volume = exp(-8.398596 + 2.4688 * ln(D))
```

Inputs: D = Diameter at breast height (1.3 m) (cm).
The source's own form: exp(-8.398596 + 2.4688 * ln(DBH)), with DBH in cm; output in m3.
Cite: https://treeallometry.org/equations/qirom-2020-non-dipterocarpaceae-ln-d/#canonical

## What it covers

- Output: Stem volume, m³
- Taxon: Non-dipterocarp species group (P. rostratum, C. soulattri, D. pectinatum, as printed) (mixed species); broadleaf
- Where: IUPHHK PT Tingang Karya Mandiri peat swamp forest, Central Kalimantan. Cite: https://treeallometry.org/equations/qirom-2020-non-dipterocarpaceae-ln-d/#where
- Biomes: tropical
- Stand: natural
- Trees measured: 42. Cite: https://treeallometry.org/equations/qirom-2020-non-dipterocarpaceae-ln-d/#n_trees
- DBH range: 5.6–27 cm. Cite: https://treeallometry.org/equations/qirom-2020-non-dipterocarpaceae-ln-d/#dbh
- Height range: 6–24 m. Cite: https://treeallometry.org/equations/qirom-2020-non-dipterocarpaceae-ln-d/#height
- R²: 0.973. Cite: https://treeallometry.org/equations/qirom-2020-non-dipterocarpaceae-ln-d/#r2
- Method: ordinary least squares on ln(V) = a0 + a1 ln(D). Cite: https://treeallometry.org/equations/qirom-2020-non-dipterocarpaceae-ln-d/#method
- Verification: read in the original source
- Last checked: 2026-11-02. Cite: https://treeallometry.org/equations/qirom-2020-non-dipterocarpaceae-ln-d/#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

Qirom, M. A., & Akbar, A. (2020). Model Volume Kelompok Jenis Pohon pada Hutan Rawa Gambut di IUPHHK PT. Tingang Karya Mandiri, Kalimantan Tengah [The Volume Model of Tree Species Group in Peat Swamp Forest at Logging Concession Area of Tingang Karya Mandiri, Central Kalimantan]. Jurnal WASIAN, 7(1), 1-14.

- DOI: https://doi.org/10.20886/jwas.v7i1.5538
- Access: open access
- Copy we read: https://pub.kehutanan.unismuh.ac.id/index.php/wasian/article/download/97/88
- Every equation from this source: https://treeallometry.org/sources/qirom-2020/
- Cite: https://treeallometry.org/equations/qirom-2020-non-dipterocarpaceae-ln-d/#source

## The facts, in the source's words

**Equation** (Best model, non-Dipterocarpaceae group, p. 10 (Tabel 3 model 1)):

> ln (V ) = -8.398596 + 2.4688 ln (D ) ... R2 97,3 %

Cite: https://treeallometry.org/equations/qirom-2020-non-dipterocarpaceae-ln-d/#equation

**Trees measured** (Tabel 1, Penyusunan Model):

> Kelompok non-dipterocarpaceae Diameter 13,9 5,6 27,0 6,0 42

Cite: https://treeallometry.org/equations/qirom-2020-non-dipterocarpaceae-ln-d/#quote-fit-n-trees

**Our note:** Volume to a 5 cm top diameter by Smalian's formula on 2 m sections (stem volume, no branches). Diameter was taken at 1.3 m or 20 cm above ground (as printed: 'setinggi dada (1,3 m) atau 20 cm di atas permukaan tanah'); the paper does not say which trees used which. Natural-log form as printed, with no correction factor stated. Fit ranges are those of the model-development subset (70% of the trees, Table 1). Caution: Tabel 3 prints identical coefficients for models 1, 2, 5 and 6 in both the Dipterocarpaceae and non-Dipterocarpaceae groups (with different F and Se values), which looks like a typesetting error in the paper; the text on p. 10 attributes this model 1 to the non-Dipterocarpaceae group, which is the reading 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 = 8 | 0.0382 | 0.0382 | Computed from the printed form: computed from the published form (coefficients as printed) |
| D = 15 | 0.180 | 0.180 | Computed from the printed form: computed from the published form (coefficients as printed) |
| D = 25 | 0.636 | 0.636 | Computed from the printed form: computed from the published form (coefficients as printed) |

Cite: https://treeallometry.org/equations/qirom-2020-non-dipterocarpaceae-ln-d/#checks

## How to cite

Cite the source for the equation: Qirom, M. A., & Akbar, A. (2020). Model Volume Kelompok Jenis Pohon pada Hutan Rawa Gambut di IUPHHK PT. Tingang Karya Mandiri, Kalimantan Tengah [The Volume Model of Tree Species Group in Peat Swamp Forest at Logging Concession Area of Tingang Karya Mandiri, Central Kalimantan]. Jurnal WASIAN, 7(1), 1-14. https://doi.org/10.20886/jwas.v7i1.5538

Cite this page for the record and checks: Tree Allometrics (Restoration Scope), "Peat swamp forest, non-Dipterocarpaceae group, volume from D (model 1)", checked 2026-11-02, https://treeallometry.org/equations/qirom-2020-non-dipterocarpaceae-ln-d/. 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/qirom-2020-non-dipterocarpaceae-ln-d.json
Report a problem: email info@restorationscope.com with the equation id (qirom-2020-non-dipterocarpaceae-ln-d) and where the right value appears.