Tree Allometrics

Abies lasiocarpa / Branch biomass

Canadian national equation, alpine fir, dbh only (branches; Table 3)

Branch biomassAbies lasiocarpa · PinaceaeCanadaRead from the original paper
Photo of Abies lasiocarpa
© Kaden Slone · CC BY · iNaturalist
Equation

As printed (Eq. 2)

y branches = β branches1D βbranches2 + e branches

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

Branch biomass = 0.0121 * D^2.3519
D
Diameter at breast height (1.3 m), cm

All branches, cut at the stem base (live branches; dead branches excluded). r2 is the adjusted R² (AdjRSq) of this compartment in Table 5. Fitted on the original scale (weighted nonlinear seemingly unrelated regression), so there is no back-transform correction. Dead branches, cones and fruits are not part of aboveground biomass in this work (Materials). Stand type was not always recorded. Ung, Bernier & Guo (2008) later revised parameters for some species with British Columbia data; not used here.

Source
bbranches1 0.0121
Equation · Table 3, Alpine fir
bbranches2 2.3519
Equation · Table 3, Alpine fir
Alpine fir 60 19.6±1.3 14.8±0.8 158.4±19.5
Trees measured · Table 2 (No. of trees)
(2.1;36.5) (2.2;23.7) (1.7;461.8)
Smallest DBH · Table 2, Alpine fir (ranges of dbh, height, total biomass)
Branches 0.0004 0.75 10.4 3.80 0.0009 0.72 11.0 3.56
R² · Table 5, Alpine fir (AdjRSq in the dbh-based set, first block)
Trees measured
60
DBH range
2.1–36.5 cm
R²
0.75
Method
Nonlinear seemingly unrelated regression with weight functions; additivity constrained so compartments sum to total
Where
Alberta, Canada (ENFOR archival data, early 1980s)
Last checked
2026-11-03
Calculate
13.9
Branch biomass (kg)
6.53
Carbon (kg), ×0.47
23.9
CO₂e (kg), ×44/12
Fitted DBH range01020304050607080510152025303540DBH (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 = 2013.913.9Computed from the printed form
computed from the published form at dbh = 20 cm

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