Equations / Aboveground biomass

Coprosma robusta (Massey University): AGB from D and H (Table 7)

Aboveground biomassCoprosma robusta · RubiaceaeNew ZealandmixedRead from the original paper

Equation

As printed (Table 7)

C. robusta Massey University ln(AGB) =ln (a)+b×ln(D)+c×ln(H) -3.53** 2.16** 0.27 ns … CF 1.02

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

Aboveground biomass = 1.02 * exp(-3.53 + 2.16 * ln(DRC) + 0.27 * ln(H))

DRC: Root collar / stem base diameter, cm
H: Total tree height, m

AGB is the sum of stem, branch and foliage dry biomass of the shrub. Natural log. D is the basal stem diameter over bark about 10 cm above ground (multi-stemmed shrubs: square root of the sum of stem diameters), mapped to DRC; H is total height in m. Table 7 reports adjusted R2 = 0.886 and RMSE = 0.132 (not used as r2 or rse). Shrubs had basal diameter up to 10 cm (mean D 3.4 to 3.8 cm by species, Table 4); the paper prints no D range for these models. The CF column is the factor the paper applies to back-transformed predictions.

Source

Wangui, J. C., Pain, S. J., Kenyon, P. R., Tozer, P. R., & Millner, J. P. (2026). Biomass and carbon estimation for three browsable native shrubs in New Zealand. New Zealand Journal of Forestry Science, 56, 16.

doi:10.33494/nzjfs562026x567x · Open access · copy we read

CF = e(RSE²/2) Equation 2; Table 7 CF column 1.02

Correction factor · Methods, Equation 2; Table 7

Trees measured: 6
Correction factor: 1.02 (applied)
Method: OLS regression on natural logarithms (power form), back-transformed with correction factor CF = exp(RSE^2/2)
Where: Massey University natural reserves and Dairy4 farm trial site
Last checked: 2026-11-02

Calculate

Root collar diameter (cm)Height (m)

Height from

0.134

Aboveground biomass (kg)

0.063

Carbon (kg), ×0.47

0.23

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
DRC = 2, H = 1	0.134	0.134	Computed from the printed form computed from the published form (a is ln(a), CF applied, coefficients as printed)
DRC = 4, H = 2	0.720	0.720	Computed from the printed form computed from the published form (a is ln(a), CF applied, coefficients as printed)
DRC = 8, H = 3	3.59	3.59	Computed from the printed form computed from the published form (a is ln(a), CF applied, coefficients as printed)

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Coprosma robusta, NZ, total aboveground biomass from RCD (Table 3) · Marden et al. 2025 · Root collar diameter
Coprosma robusta (all sites): AGB from D and H (Table 7) · Wangui et al. 2026 · Root collar diameter + Height
Native shrubs NZ (3 spp, all sites): AGB from D (Table 7) · Wangui et al. 2026 · Root collar diameter
Native shrubs NZ (3 spp, Massey University): AGB from D and H (Table 7) · Wangui et al. 2026 · Root collar diameter + Height
Coprosma robusta (all sites): AGB from D and H (Table 7) · same paper · Aboveground biomass
Native shrubs NZ (3 spp, all sites): AGB from D (Table 7) · same paper · Aboveground biomass
Native shrubs NZ (3 spp, Massey University): AGB from D and H (Table 7) · same paper · Aboveground biomass
Melicytus ramiflorus (Limestone Downs): AGB from D (Table 7) · same paper · Aboveground biomass
Pittosporum crassifolium (Massey University): AGB from D and H (Table 7) · same paper · Aboveground biomass

Compare these curves

Coprosma robusta (Massey University): AGB from D and H (Table 7)

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