Tree Allometrics

Picea mariana / Stem biomass

Canadian national equation, black spruce, dbh only (stem wood plus stem bark; Table 3)

Stem biomassPicea mariana · PinaceaeCanadaRead from the original paper
Photo of Picea mariana
© 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 = 0.0477 * D^2.5147 + 0.0153 * D^2.2429
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
Black spruce bwood1 0.0477
Equation · Table 3, Black spruce
bwood2 2.5147
Equation · Table 3, Black spruce
bbark1 0.0153
Equation · Table 3, Black spruce
bbark2 2.2429
Equation · Table 3, Black spruce
Black spruce 1534 13.9±0.2 11.6±0.1 73.3±1.9
Trees measured · Table 2 (No. of trees)
(1.6;37.2) (1.8;23.5) (0.6;556.1)
Smallest DBH · Table 2, Black spruce (ranges of dbh, height, total biomass)
Stem 0.0189 0.93 15.6 3.19 0.0009 0.98 7.4 3.85
R² · Table 5, Black spruce (AdjRSq in the dbh-based set, first block)
Trees measured
1,534
DBH range
1.6–37.2 cm
R²
0.93
Method
Nonlinear seemingly unrelated regression with weight functions; additivity constrained so compartments sum to total
Where
Canada: Alberta, Manitoba, Newfoundland and Labrador, Nova Scotia, Northwest Territories, Ontario, Quebec, Saskatchewan, Yukon (ENFOR archival data, early 1980s)
Last checked
2026-11-03
Calculate
102
Stem biomass (kg)
47.9
Carbon (kg), ×0.47
176
CO₂e (kg), ×44/12
Fitted DBH range0100200300400500600510152025303540DBH (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 = 20102102Computed from the printed form
computed from the published form at dbh = 20 cm

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