Tree Allometrics

Equations / Aboveground biomass

AGB Model 3 (DBH, H and [ln(DBH)]²), peat swamp forest Sarawak

Aboveground biomassMixed tree species, tropical peat swamp forestMalaysianaturalRead from the original paper
Many species, no single photo
Equation

As printed (Models section, p. 15)

Model 3: ln(DW)=a+b ln(DBH)+c ln(H)−e [ln(DBH)]2

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

Aboveground biomass = 1.0444 * exp(-3.8903 + 3.17 * ln(D) + 0.5108 * ln(H) - 0.2013 * ln(D)^2)
D
Diameter at breast height (1.3 m), cm
H
Total tree height, m

Coefficients a-e as printed in Table 5; the e term enters with a minus sign per the model definitions. WD is wood density in Mg m-3, numerically equal to g/cm3. Back-transformed result multiplied by the printed CF. Adjusted R2 0.9704 is not entered as r2. DW is dry mass (kg) of the whole above- or belowground part; hollow cavity volume was measured separately and the models are fitted to the measured biomass of hollow trees.

Source
Model 3 −3.8903 3.1700 *** 0.5108 ns 0.2013 ** 0.9704 1.0444 21.99 0.00300
Equation · Table 5, Aboveground biomass, p. 19 (columns a, b, c, d, e, adjusted R2, CF, AIC, FI)
Aboveground biomass (n=41)
Trees measured · Table 5
AGB data were obtained for trees ranging in DBH from 5.2 to 97.0 cm
Largest DBH · Discussion, p. 20
Trees measured
41
DBH range
5.2–97 cm
Correction factor
1.0444 (applied)
Method
log-log regression of dry weight on ln-transformed predictors, back-transformed and multiplied by the correction factor CF = exp(RSE²/2)
Where
Logged-over peat swamp forest, Sarawak (Alan Batu and other sites, PC1-PC3)
Last checked
2026-11-02
Calculate
Height from
38.6
Aboveground biomass (kg)
18.2
Carbon (kg), ×0.47
66.6
CO₂e (kg), ×44/12
Fitted DBH range0100200300400500600510152025303540DBH (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 = 10, H = 1238.638.6Computed from the printed form
computed from the published form (coefficients and CF as printed)
D = 30, H = 22485485Computed from the printed form
computed from the published form (coefficients and CF as printed)
D = 60, H = 301,7991,799Computed from the printed form
computed from the published form (coefficients and CF as printed)

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