Equations / Aboveground biomass
Wet tropical zone AGB, quadratic (Brown 1997 Eq. 3.2.5)
As printed (Eq. 3.2.5, Section 3.2.1 table)
In this library's units, ready to compute (kg)
Aboveground biomass = 21.297 - 6.953 * D + 0.740 * D^2D- Diameter at breast height (1.3 m), cm
Commonly cited as Brown (1997) Eq. 3.2.5, but the primer's footnote c attributes it to Brown and Iverson (1992), which could not be read; taken from Brown (1997). r2 is adjusted r². The primer does not say whether a log back-transform correction is included; none applied. Climatic zones per the primer: dry <1500 mm/yr rain with a dry season of several months; moist 1500–4000 mm/yr; wet >4000 mm/yr, lowland conditions only.
https://www.fao.org/4/w4095e/w4095e0b.htm · Paywalled · compilation we read
Y= biomass per tree in kg, D = dbh in cm, and BA = basal area in cm2
c From Brown and Iverson (1992)
4-112 | 169 | 0.92
- Trees measured
- 169
- DBH range
- 4–112 cm
- R²
- 0.92
- Where
- Tropics, wet zone
- Last checked
- 2026-11-01
Shaded: the DBH range the model was fitted on. Other inputs held at the values above.
On every build, the library's form and the paper's own form (in its units) must both give these values within 1%.
| Inputs | Expected | We get | From |
|---|---|---|---|
| D = 30 | 478.7 | 478.7 | Computed from the printed form computed with python3 from the published form |
Related
- Dry tropical zone AGB from DBH (Eq. 3.2.1) · Brown 1997 · DBH
- Moist tropical zone AGB, power law (Eq. 3.2.4) · Brown 1997 · DBH
- Moist tropical zone AGB, quadratic (Eq. 3.2.3) · Brown 1997 · DBH