Tree Allometrics

Acacia auriculiformis × Acacia mangium / Stem biomass

Acacia auriculiformis × Acacia mangium (hybrid) plantation, stem biomass from stump diameter (SB6)

Stem biomassAcacia auriculiformis × Acacia mangium (hybrid)BangladeshplantationRead from the original paper
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Equation

As printed (Table 3, model SB6 (columns: β0, β1, RMSE, F, adjusted R2, AIC, average deviation, CF, DW))

SB6 Hybrid −2.426*** 2.205*** 0.207 4186 0.9546 −57.95 17.266 1.0217 2.031

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

Stem biomass = 1.0217 * exp(-2.426 + 2.205 * ln(D30))
D30
Stem diameter at 30 cm, cm

Stem biomass only (bark included, oven-dry), so output is stem_biomass not agb. Form read as ln(SB) = β0 + β1 ln(dst) from the text calling SB6 the "ln–ln stump-based model"; the full model list is in a supplementary Table S1 that was not read. The Table 3 CF (1.0217) is applied in both forms. Table 3 caption says RMSE is in kg but the body values (about 0.2) are log-scale (CF 1.0193 matches exp(0.196²/2)), so the body is followed and rse is not stored. Table 3 gives no DBH range for the 25 calibration trees, so none is stored. Row label "Hybrid" in Table 3 maps to this taxon.

Source
The ln–ln stump-based model (SB6) was parsimonious and produced adjusted R2 values of 0.945–0.968 across species
Equation · Section 3.3
stump diameter (dst, measured at 30 cm above ground)
Units · Abstract
Biomass estimates refer specifically to stem biomass; branch, foliage, and root components were not included.
Output · Section 2.4
Calibration models were developed using 75 destructively sampled trees (25 per species, covering small, medium and large diameter classes)
Trees measured · Section 2.2
All log transformations used natural logs (ln).
method · Section 2.5
Trees measured
25
R²
0.9546
Correction factor
1.0217 (applied)
Method
OLS on ln-transformed data (ln-ln), adjusted R2
Where
Ten plantation sites, Sylhet Division, Bangladesh
Last checked
2026-11-02
Calculate
163
Stem biomass (kg)
76.7
Carbon (kg), ×0.47
281
CO₂e (kg), ×44/12
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
D30 = 30163163Computed from the printed form
hand-computed from the published form
D30 = 50503503Computed from the printed form
hand-computed from the published form

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