Equations / Stem biomass

Scots pine stem biomass, ln-ln OLS (D and H)

Stem biomassPinus sylvestris · PinaceaeMongolianaturalRead from the original paper

Equation

As printed (Table 4, stem section, Eq. 6, type N, p. 17)

lnŶ=lna+b x lnD+c x lnH; N: lna = -4.235, b = 1.741, c = 1.284, CF = 1.009

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

Stem biomass = 1.009 * exp(-4.235 + 1.741 * ln(D) + 1.284 * ln(H))

D: Diameter at breast height (1.3 m), cm
H: Total tree height, m

Ordinary least squares (type N) rows of Table 4 with the printed CF applied; the weighted (type W) rows are not included because their printed RMSE/CF are on a weighted scale. The paper does not say whether the printed lna values for type N are rounded further. Table 4 decimal commas read as decimal points. The abstract names the D and H form (Eq. 6) as the best-fitting; the D-only form is also given. Total AGB = stem + branches + needles; the paper also describes a one-step proportional weighting for additivity, not applied here. Biomass in kg (Eq. 1 text).

Source

Tungalag, M., Altanzagas, B., Gerelbaatar, S., & Dorjsuren, Ch. (2020). Tree-level above-ground biomass equations for Pinus sylvestris L. in Mongolia. Mongolian Journal of Biological Sciences, 18(1), 13-21.

doi:10.22353/mjbs.2020.18.02 · Open access · copy we read

A total of 35 sample trees were destructively sampled

Trees measured · Materials and Methods, Data collection, p. 14

Trees measured: 35
DBH range: 4.7–55 cm
Height range: 4.6–23 m
Correction factor: 1.009 (applied)
Method: ordinary least squares on ln-transformed data (type N), with correction factor CF = exp(RMSE²/2)
Where: Northeastern Khangai and western Khentii forest regions, northern Mongolia
Last checked: 2026-11-02

Calculate

DBH (cm)Height (m)

Height from

11.62

Stem biomass (kg)

5.462

Carbon (kg), ×0.47

20.03

CO₂e (kg), ×44/12

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%.

Inputs	Expected	We get	From
D = 10, H = 8	11.6	11.6	Computed from the printed form computed from the published form (coefficients as printed)
D = 25, H = 16	139.5	139.5	Computed from the printed form computed from the published form (coefficients as printed)
D = 45, H = 21	550.3	550.3	Computed from the printed form computed from the published form (coefficients as printed)

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Scots pine AGB biomass, ln-ln OLS (D only) · same paper · Aboveground biomass
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Scots pine stem biomass, ln-ln OLS (D only) · same paper · Stem biomass

Compare these curves

Scots pine stem biomass, ln-ln OLS (D and H)

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