Tree Allometrics

Equations / Aboveground biomass

Total AGB from DBH squared, log form (Eq. 11)

Aboveground biomassSeven dominant canopy species (Carapa guianensis, Inga coruscans, Laetia procera, Pentaclethra macroloba, Stryphnodendron microstachyum, Tapirira guianensis, Vochysia ferruginea)Costa RicanaturalRead from the original paper

Fitted on these 7 species: Carapa guianensis, Inga coruscans, Laetia procera, Pentaclethra macroloba, Stryphnodendron microstachyum, Tapirira guianensis, Vochysia ferruginea

4 of the 7 species it was fitted on · iNaturalist photos, hover for credit
Equation

As printed (Table 5, Eq. 11)

ln B tot = c + a DBH2; c 0.76 ± 0.16; a 0.00015 ± 0.000023

In this library's units, ready to compute (kg)

Aboveground biomass = 1000 * exp(0.76 + 0.00015 * D^2)
D
Diameter at breast height (1.3 m), cm

No back-transform correction factor is stated, so none is applied. Only trees with DBH ≥ 60 cm were harvested; the authors warn the models tend to overestimate outside 60-105 cm. Table 5 gives B tot in 'mg/tree', meaning Mg (Table 3 reports total biomass in Mg, mean 6.7 Mg); the canonical expression multiplies by 1000 to give kg. Recommended by the authors with Eq. 12 because they need DBH only. The printed form 'ln B tot = c + a DBH2' is read as DBH squared (the coefficient 0.00015 and the prediction scale only fit that reading). Includes foliage (stem plus branches and foliage).

Source
19 individual trees were measured before harvest
Trees measured · Methods, p. 3
adjusted well in the interval of diameters sampled (60–105 cm)
Largest DBH · Discussion, p. 7
Trees measured
19
DBH range
60–105 cm
R²
0.71
Method
Least-squares regression (SAS), r2 is the adjusted coefficient of determination
Where
Tirimbina (Sarapiquí) and Corinto (Guápiles), northern Costa Rica
Last checked
2026-11-02
Calculate
5,585
Aboveground biomass (kg)
2,625
Carbon (kg), ×0.47
9,624
CO₂e (kg), ×44/12
Fitted DBH range020,00040,00060,00080,000100,00020406080100120140160DBH (cm)Aboveground biomass (kg)Aboveground biomass

Shaded: the DBH range the model was fitted on. Other inputs held at the values above.

Checks this equation passes

On every build, the library's form and the paper's own form (in its units) must both give these values within 1%.

InputsExpectedWe getFrom
D = 805,5855,585Computed from the printed form
computed from the printed coefficients

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