Equations / Stem biomass
Picea spp. stem biomass, cross-sectional area at 0.3 m (NLS)
Stem biomassPicea spp. · PinaceaeCanadanaturalRead from the original paper
Covers the whole genus
Equation
As printed (Table 3, Eqs. 2-5)
Picea spp. Stems NLS 42.8437 1.2201 0.929 (columns: β, SE(β), α, SE(α), RMSE, R2); y = βx^α + ε (Eq. 2)
In this library's units, ready to compute (kg)
Stem biomass = 42.8437 * (0.785398163397448 * D30^2)^1.2201 / 1000D30- 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
doi:10.3390/f12020234 · Open access · copy we read
- R²
- 0.929
- 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
0.173
Stem biomass (kg)
0.0814
Carbon (kg), ×0.47
0.298
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%.
| Inputs | Expected | We get | From |
|---|---|---|---|
| D30 = 2 | 0.173 | 0.173 | Computed from the printed form computed from the published form (coefficients as printed) |
| D30 = 5 | 1.62 | 1.62 | Computed from the printed form computed from the published form (coefficients as printed) |
| D30 = 8 | 5.1 | 5.1 | Computed from the printed form computed from the published form (coefficients as printed) |
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