Tree Allometrics

Equations / Branch biomass

Guangzhou subtropical forest branch biomass, Model 1 (DBH only)

Branch biomassSubtropical evergreen broadleaf forest trees (Castanopsis fissa, Aleurites montana, Castanopsis chinensis, Machilus chinensis and 22 companion species)ChinanaturalRead from the original paper
Many species, no single photo
Equation

As printed (Section 2.4, Eq. 1)

ln(B) = a + bln(DBH²)

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

Branch biomass = exp(-4.342 + 1.352 * ln(D^2))
D
Diameter at breast height (1.3 m), cm

ln(B) = a + bln(DBH²). Fitted in R (nlme) on ln-transformed biomass; the paper states no back-transform correction factor and none is applied. Aboveground biomass is above a 10 cm stump (stem, branches, leaves); belowground is the root system plus stump. The paper lists five models (1)-(5); model (2) (ln DBH²H) and (4) (ln DBH²WD) are not added here.

Source
(1) −4.342 ± 0.187 1.352 ± 0.032 0.000 0.881 45.3 53.35 −9.93
Equation · Table A1, Branch
(1) −4.342 ± 0.187 1.352 ± 0.032 0.000 0.881 45.3 53.35 −9.93
R² · Table A1, Branch
a total of 144 sampled trees
Trees measured · Section 2.2
Total 4.2 61.2
Smallest DBH · Table 1
Trees measured
144
DBH range
4.2–61.2 cm
R²
0.881
Method
ln-ln regression (R, nlme)
Where
Fushan, about 26 km northeast of Guangzhou, Guangdong
Last checked
2026-11-02
Calculate
19.7
Branch biomass (kg)
9.259
Carbon (kg), ×0.47
33.95
CO₂e (kg), ×44/12
Fitted DBH range050100150200250300510152025303540DBH (cm)Branch biomass (kg)Branch 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 = 1519.719.7Computed from the printed form
hand-computed from the published form
D = 40279.4279.4Computed from the printed form
hand-computed from the published form

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