Tree Allometrics

Pseudotsuga menziesii / Branch biomass

Douglas-fir branch biomass, simple SUR (D only)

Branch biomassPseudotsuga menziesii · PinaceaeUnited StatesmixedRead from the original paper
Photo of Pseudotsuga menziesii
© Danny Steaven · CC BY-SA · iNaturalist
Equation

As printed (Eqs. 2-5 (X1 = ln DBH) and Table 3, Simple SUR, Douglas-fir)

Branch = exp(a31 + a32*X1); a31 = -2.604, a32 = 1.942

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

Branch biomass = exp(-2.604 + 1.942 * ln(D))
D
Diameter at breast height (1.3 m), cm

Read from the author's accepted manuscript (draft, manuscript ID cjfr-2015-0256.R1), not the typeset article; values may differ from the final print. Fitted in original scale (nonlinear SUR), so no log back-transform correction. DBH in cm, biomass in kg (Eq. 2-5 text). Extended SUR models using height and crown length are not included (crown length is not a canonical variable).

Source
22 Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco) and 33 lodgepole pine (Pinus contorta) trees
Trees measured · Materials and Methods, Data and Study Area
Trees measured
22
DBH range
19.3–114 cm
Method
seemingly unrelated regression (simple SUR), component equations constrained to sum to total, fitted in original scale
Where
Oregon, USA (several forests)
Last checked
2026-11-02
Calculate
24.9
Branch biomass (kg)
11.7
Carbon (kg), ×0.47
42.9
CO₂e (kg), ×44/12
Fitted DBH range020406080100510152025303540DBH (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 = 2024.924.9Computed from the printed form
computed from the published form (coefficients as printed)
D = 50147147Computed from the printed form
computed from the published form (coefficients as printed)
D = 100566566Computed from the printed form
computed from the published form (coefficients as printed)

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