# Caribbean Costa Rica secondary forest (35 species), root biomass from DBH

Root biomass equation for Secondary forest trees, 35 species (highest-IVI species per diameter class), Costa Rica, from Fonseca G. et al. 2009. 122 trees, DBH 2.8–28.2 cm. Listed on Tree Allometrics, a free library of tree allometric equations, each quoted from the source that published it.

## Equation

As printed in Fonseca G. et al. 2009 (Cuadro 2, Bosque secundario):

> Bra = exp(-3,98702 + 2,48739*ln(d)) 91,25 0,5053 – 122 1,14

Cite: https://treeallometry.org/equations/fonseca-2009-secondary-forest-roots/#equation

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

```
Root biomass = 1.14 * exp(-3.98702 + 2.48739 * ln(D))
```

Inputs: D = Diameter at breast height (1.3 m) (cm).
The source's own form: 1.14 * exp(-3.98702 + 2.48739 * ln(d)), with d in cm; output in kg.
Cite: https://treeallometry.org/equations/fonseca-2009-secondary-forest-roots/#canonical

## What it covers

- Output: Root biomass, kg
- Taxon: Secondary forest trees, 35 species (highest-IVI species per diameter class) (mixed species); broadleaf
- Where: Caribbean (Atlantic) lowlands of Costa Rica. Cite: https://treeallometry.org/equations/fonseca-2009-secondary-forest-roots/#where
- Biomes: tropical
- Stand: natural
- Trees measured: 122. Cite: https://treeallometry.org/equations/fonseca-2009-secondary-forest-roots/#n_trees
- DBH range: 2.8–28.2 cm. Cite: https://treeallometry.org/equations/fonseca-2009-secondary-forest-roots/#dbh
- R²: 0.9125. Cite: https://treeallometry.org/equations/fonseca-2009-secondary-forest-roots/#r2
- Residual SE: 0.5053. Cite: https://treeallometry.org/equations/fonseca-2009-secondary-forest-roots/#rse
- Correction factor: 1.14 (applied). Cite: https://treeallometry.org/equations/fonseca-2009-secondary-forest-roots/#cf
- Method: OLS on ln(Bra) vs ln(d); Sprugel correction factor. Cite: https://treeallometry.org/equations/fonseca-2009-secondary-forest-roots/#method
- Verification: read in the original source
- Last checked: 2026-11-01. Cite: https://treeallometry.org/equations/fonseca-2009-secondary-forest-roots/#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

Fonseca G., W., Alice G., F., & Rey B., J. M. (2009). Modelos para estimar la biomasa de especies nativas en plantaciones y bosques secundarios en la zona Caribe de Costa Rica. Bosque (Valdivia), 30(1), 36–47.

- DOI: https://doi.org/10.4067/S0717-92002009000100006
- Access: open access
- Copy we read: https://www.scielo.cl/pdf/bosque/v30n1/art06.pdf
- Every equation from this source: https://treeallometry.org/sources/fonseca-2009/
- Cite: https://treeallometry.org/equations/fonseca-2009-secondary-forest-roots/#source

## The facts, in the source's words

**Equation** (Cuadro 2, Bosque secundario):

> Bra = exp(-3,98702 + 2,48739*ln(d)) 91,25 0,5053 – 122 1,14

Cite: https://treeallometry.org/equations/fonseca-2009-secondary-forest-roots/#equation

**Smallest DBH** (Métodos, p. 37):

> En estos bosques la muestra fue de 160 árboles correspondientes a 35 especies, cuyo diámetro varió entre 2,8 cm y 28,2 cm

Cite: https://treeallometry.org/equations/fonseca-2009-secondary-forest-roots/#quote-fit-dbh-min-cm

**Correction factor** (Métodos, p. 39):

> Los modelos seleccionados con transformaciones logarítmicas fueron corregidos utilizando un factor de corrección (FC)

Cite: https://treeallometry.org/equations/fonseca-2009-secondary-forest-roots/#quote-fit-cf

**Our note:** Root (Bra) dry biomass per tree from excavated root systems, secondary forests 3–20 years old. FC = 1,14 multiplied in. The secondary-forest total-biomass model in Cuadro 2 is not included: it is printed as 'Log(Bt) = -1,80246 + 2,28927*ln(d)' with Log defined as base 10, which gives implausible values; the base is ambiguous.

## 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 | 17.8 | 17.8 | Computed from the printed form: computed from the Cuadro 2 model times FC 1,14 |

Cite: https://treeallometry.org/equations/fonseca-2009-secondary-forest-roots/#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: Fonseca G., W., Alice G., F., & Rey B., J. M. (2009). Modelos para estimar la biomasa de especies nativas en plantaciones y bosques secundarios en la zona Caribe de Costa Rica. Bosque (Valdivia), 30(1), 36–47. https://doi.org/10.4067/S0717-92002009000100006

Cite this page for the record and checks: Tree Allometrics (Restoration Scope), "Caribbean Costa Rica secondary forest (35 species), root biomass from DBH", checked 2026-11-01, https://treeallometry.org/equations/fonseca-2009-secondary-forest-roots/. 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/fonseca-2009-secondary-forest-roots.json
Report a problem: email info@restorationscope.com with the equation id (fonseca-2009-secondary-forest-roots) and where the right value appears.