# Quercus robur and Q. petraea, Germany, belowground biomass from DBH (Eq. 4, Tab. 1)

Root biomass equation for Quercus (Q. robur and Q. petraea pooled), Germany, from Röhling et al. 2019. 39 trees, DBH 7.4–42 cm. Listed on Tree Allometrics, a free library of tree allometric equations, each quoted from the source that published it.

Fitted on Quercus robur, Quercus petraea.

## Equation

As printed in Röhling et al. 2019 (Eq. 4 and Tab. 1, p. 168):

> BGB = β1 · DBH^β2; Oak β1 0.040113 (0.0253-0.0548), β2 2.227842 (2.1179-2.3377), ME 0.98, RMSE 5.2

Cite: https://treeallometry.org/equations/rohling-2019-bgb-oak/#equation

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

```
Root biomass = 0.040113 * D^2.227842
```

Inputs: D = Diameter at breast height (1.3 m) (cm).
The source's own form: 0.040113 * DBH^2.227842, with DBH in cm; output in kg.
Cite: https://treeallometry.org/equations/rohling-2019-bgb-oak/#canonical

## What it covers

- Output: Root biomass, kg
- Taxon: Quercus (Q. robur and Q. petraea pooled) (genus), family Fagaceae; broadleaf
- Where: 20 forest stands in Brandenburg, Saxony-Anhalt and Thuringia, Germany. Cite: https://treeallometry.org/equations/rohling-2019-bgb-oak/#where
- Biomes: temperate
- Stand: mixed
- Trees measured: 39. Cite: https://treeallometry.org/equations/rohling-2019-bgb-oak/#n_trees
- DBH range: 7.4–42 cm. Cite: https://treeallometry.org/equations/rohling-2019-bgb-oak/#dbh
- Method: weighted (1/DBH²) nonlinear least squares power function. Cite: https://treeallometry.org/equations/rohling-2019-bgb-oak/#method
- Verification: read in the original source
- Last checked: 2026-11-02. Cite: https://treeallometry.org/equations/rohling-2019-bgb-oak/#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

Röhling, S., Demant, B., Dunger, K., Neubauer, M., Oehmichen, K., Riedel, T., & Stümer, W. (2019). Equations for estimating belowground biomass of Silver Birch, Oak and Scots Pine in Germany. iForest, 12, 166-172.

- DOI: https://doi.org/10.3832/ifor2862-012
- Access: open access
- Copy we read: https://iforest.sisef.org/pdf/?id=ifor2862-012
- Every equation from this source: https://treeallometry.org/sources/rohling-2019/
- Cite: https://treeallometry.org/equations/rohling-2019-bgb-oak/#source

## The facts, in the source's words

**Equation** (Eq. 4 and Tab. 1, p. 168):

> BGB = β1 · DBH^β2; Oak β1 0.040113 (0.0253-0.0548), β2 2.227842 (2.1179-2.3377), ME 0.98, RMSE 5.2

Cite: https://treeallometry.org/equations/rohling-2019-bgb-oak/#equation

**Trees measured** (Material and methods, Study sites, p. 167):

> 48 Birches, 39 Oaks and 54 Pines were sampled

Cite: https://treeallometry.org/equations/rohling-2019-bgb-oak/#quote-fit-n-trees

**Largest DBH** (Study sites, pp. 167-168):

> DBH ranged from 7.2 up to 53.2 cm for Pine, from 7.4 to 42.0 cm for Oak and from 8.2 to 52.9 cm for Birch

Cite: https://treeallometry.org/equations/rohling-2019-bgb-oak/#quote-fit-dbh-max-cm

**Our note:** Dry mass of coarse roots (2 mm and thicker) including the belowground stump; fine roots excluded. Units not printed beside Tab. 1 but BGB is reported in kg and DBH in cm throughout the paper. The paper gives model efficiency (ME) and RMSE, not R², so none is recorded.

## 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 | 6.78 | 6.78 | Computed from the printed form: hand-computed from the published form |
| D = 25 | 52.2 | 52.2 | Computed from the printed form: hand-computed from the published form |
| D = 40 | 149 | 149 | Computed from the printed form: hand-computed from the published form |

Cite: https://treeallometry.org/equations/rohling-2019-bgb-oak/#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: Röhling, S., Demant, B., Dunger, K., Neubauer, M., Oehmichen, K., Riedel, T., & Stümer, W. (2019). Equations for estimating belowground biomass of Silver Birch, Oak and Scots Pine in Germany. iForest, 12, 166-172. https://doi.org/10.3832/ifor2862-012

Cite this page for the record and checks: Tree Allometrics (Restoration Scope), "Quercus robur and Q. petraea, Germany, belowground biomass from DBH (Eq. 4, Tab. 1)", checked 2026-11-02, https://treeallometry.org/equations/rohling-2019-bgb-oak/. 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/rohling-2019-bgb-oak.json
Report a problem: email info@restorationscope.com with the equation id (rohling-2019-bgb-oak) and where the right value appears.