Tree Allometrics

Thuja occidentalis / Stem biomass

Canadian national equation, eastern white-cedar, dbh only (stem wood plus stem bark; Table 3)

Stem biomassThuja occidentalis · CupressaceaeCanadaRead from the original paper
Photo of Thuja occidentalis
© Douglas Goldman · CC BY-SA · iNaturalist
Equation

As printed (Eq. 2)

y wood = β wood1D βwood2 + ewood

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

Stem biomass = 0.0654 * D^2.2121 + 0.0114 * D^2.1432
D
Diameter at breast height (1.3 m), cm

Stem from ground level to tree top, stem wood plus stem bark; the stem is the sum of the two compartment equations. 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
y bark = β bark1D βbark2 + e bark
Equation · Eq. 2
Eastern white-cedar bwood1 0.0654
Equation · Table 3, Eastern white-cedar
bwood2 2.2121
Equation · Table 3, Eastern white-cedar
bbark1 0.0114
Equation · Table 3, Eastern white-cedar
bbark2 2.1432
Equation · Table 3, Eastern white-cedar
Eastern white-cedar 184 20.8±0.9 11.8±0.3 117.2±9.3
Trees measured · Table 2 (No. of trees)
(2.1;66.2) (1.9;21.9) (1.0;917.4)
Smallest DBH · Table 2, Eastern white-cedar (ranges of dbh, height, total biomass)
Stem 0.0172 0.95 22.5 2.99 0.0013 0.97 16.7 3.62
R² · Table 5, Eastern white-cedar (AdjRSq in the dbh-based set, first block)
Trees measured
184
DBH range
2.1–66.2 cm
R²
0.95
Method
Nonlinear seemingly unrelated regression with weight functions; additivity constrained so compartments sum to total
Where
Ontario and Quebec, Canada (ENFOR archival data, early 1980s)
Last checked
2026-11-03
Calculate
56.4
Stem biomass (kg)
26.5
Carbon (kg), ×0.47
97.2
CO₂e (kg), ×44/12
Fitted DBH range050100150200250300510152025303540DBH (cm)Stem biomass (kg)Stem 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 = 2056.456.4Computed from the printed form
computed from the published form at dbh = 20 cm

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