Tree Allometrics

Equations / Branch biomass

Picea spp. branch biomass, cross-sectional area at 0.3 m (NLS)

Branch biomassPicea spp. · PinaceaeCanadanaturalRead from the original paper
Covers the whole genus
Equation

As printed (Table 3, Eqs. 2-5)

Picea spp. Branches NLS 19.1842 1.2866 0.904 (columns: β, SE(β), α, SE(α), RMSE, R2); y = βx^α + ε (Eq. 2)

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

Branch biomass = 19.1842 * (0.785398163397448 * D30^2)^1.2866 / 1000
D30
Stem diameter at 30 cm, cm

Paper's predictor is cross-sectional area (cm2) of the stem(s) at 0.3 m; converted here to D30 as pi/4 * D30^2 (pi written as 0.785398163397448 * ...), so for multi-stemmed trees D30 is the equivalent diameter of the summed cross-sectional area. Paper output is in g dry mass; canonical form divides by 1000. Fit range of the predictor is not stated, so none is given.

Source
R²
0.904
Method
iterative nonlinear least squares power function, y = β x^α (unweighted), x = cross-sectional area
Where
Sporadic to discontinuous permafrost zone, Taiga Plains and Taiga Shield ecozones, northwestern Canada
Last checked
2026-11-02
Calculate
0.0837
Branch biomass (kg)
0.0393
Carbon (kg), ×0.47
0.144
CO₂e (kg), ×44/12
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
D30 = 20.08370.0837Computed from the printed form
computed from the published form (coefficients as printed)
D30 = 50.8840.884Computed from the printed form
computed from the published form (coefficients as printed)
D30 = 82.962.96Computed from the printed form
computed from the published form (coefficients as printed)

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