# Chir pine height from D, quadratic (M2)

Height equation for Pinus roxburghii, Nepal, from Upadhyay & Khadka 2024. Listed on Tree Allometrics, a free library of tree allometric equations, each quoted from the source that published it.

## Equation

As printed in Upadhyay & Khadka 2024 (Table 4, M2):

> height=1.1052804+0.6252304*dbh−0.0021242*dbh2

Cite: https://treeallometry.org/equations/upadhyay-2024-h-quadratic/#equation

In this library's units, ready to compute (height in m):

```
Height = 1.1052804 + 0.6252304 * D - 0.0021242 * D^2
```

Inputs: D = Diameter at breast height (1.3 m) (cm).
The source's own form: 1.1052804 + 0.6252304 * DBH - 0.0021242 * DBH^2, with DBH in cm; output in m.
Cite: https://treeallometry.org/equations/upadhyay-2024-h-quadratic/#canonical

## What it covers

- Output: Height, m
- Taxon: Pinus roxburghii (species), family Pinaceae; conifer
- Where: Nepal, Forest Resource Assessment 2018 plots. Cite: https://treeallometry.org/equations/upadhyay-2024-h-quadratic/#where
- Biomes: subtropical, montane
- Stand: natural
- R²: 0.72. Cite: https://treeallometry.org/equations/upadhyay-2024-h-quadratic/#r2
- Method: polynomial (degree 2) regression. Cite: https://treeallometry.org/equations/upadhyay-2024-h-quadratic/#method
- Verification: read in the original source
- Last checked: 2026-11-02. Cite: https://treeallometry.org/equations/upadhyay-2024-h-quadratic/#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

Upadhyay, J., & Khadka, S. (2024). Modelling height-diameter relationship of Pinus roxburghii in Nepal. American Journal of Biological and Environmental Statistics, 10(3), 49–59.

- DOI: https://doi.org/10.11648/j.ajbes.20241003.12
- Access: open access
- Copy we read: http://article.sciencepg.com/pdf/j.ajbes.20241003.12
- Every equation from this source: https://treeallometry.org/sources/upadhyay-2024/
- Cite: https://treeallometry.org/equations/upadhyay-2024-h-quadratic/#source

## The facts, in the source's words

**Equation** (Table 4, M2):

> height=1.1052804+0.6252304*dbh−0.0021242*dbh2

Cite: https://treeallometry.org/equations/upadhyay-2024-h-quadratic/#equation

**Our note:** r2 is the adjusted R2 as printed in Table 6 (RMSE 3.639). Fitted on the 80% training split of the FRA 2018 sample; the paper's n is ambiguous (610 'sample plots' vs 610 trees in Table 3), so n_trees and ranges are left out. Table 6 coefficient columns differ from Table 4; Table 4 (printed formulas, consistent with Table 3 class means) is 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 = 10 | 7.15 | 7.15 | Computed from the printed form: computed from the published form (coefficients as printed) |
| D = 25 | 15.4 | 15.4 | Computed from the printed form: computed from the published form (coefficients as printed) |
| D = 50 | 27.1 | 27.1 | Computed from the printed form: computed from the published form (coefficients as printed) |

Cite: https://treeallometry.org/equations/upadhyay-2024-h-quadratic/#checks

## How to cite

Cite the source for the equation: Upadhyay, J., & Khadka, S. (2024). Modelling height-diameter relationship of Pinus roxburghii in Nepal. American Journal of Biological and Environmental Statistics, 10(3), 49–59. https://doi.org/10.11648/j.ajbes.20241003.12

Cite this page for the record and checks: Tree Allometrics (Restoration Scope), "Chir pine height from D, quadratic (M2)", checked 2026-11-02, https://treeallometry.org/equations/upadhyay-2024-h-quadratic/. 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/upadhyay-2024-h-quadratic.json
Report a problem: email info@restorationscope.com with the equation id (upadhyay-2024-h-quadratic) and where the right value appears.