Tree Allometrics

Fraxinus americana / Stem biomass

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

Stem biomassFraxinus americana · OleaceaeCanadaRead from the original paper
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Equation

As printed (Eq. 2)

y wood = β wood1D βwood2 + ewood

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

Stem biomass = 0.1861 * D^2.1665 + 0.0406 * D^1.9946
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
White ash bwood1 0.1861
Equation · Table 3, White ash
bwood2 2.1665
Equation · Table 3, White ash
bbark1 0.0406
Equation · Table 3, White ash
bbark2 1.9946
Equation · Table 3, White ash
White ash 109 22.3±1.1 17.6±0.4 296.2±28.5
Trees measured · Table 2 (No. of trees)
(2.4;53.7) (3.9;26.9) (1.2;1850.1)
Smallest DBH · Table 2, White ash (ranges of dbh, height, total biomass)
Stem 0.0119 0.87 80.3 3.91 0.3561 0.93 57.2 2.60
R² · Table 5, White ash (AdjRSq in the dbh-based set, first block)
Trees measured
109
DBH range
2.4–53.7 cm
R²
0.87
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
139
Stem biomass (kg)
65.1
Carbon (kg), ×0.47
239
CO₂e (kg), ×44/12
Fitted DBH range0100200300400500600700510152025303540DBH (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 = 20139139Computed from the printed form
computed from the published form at dbh = 20 cm

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