Notholithocarpus densiflorus / Root biomass

Tanoak root biomass from basal area (best AICc model, Table 2)

Root biomassNotholithocarpus densiflorus · FagaceaeUnited StatesmixedRead from the original paper

Equation

As printed (Table 2, last row (lowest AICc))

ln (Belowground biomass) = 6.683 + 0.8149( ln BA )

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

Root biomass = exp(6.683 + 0.8149 * ln(0.000078539816 * D^2))

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

The paper's predictor is total stem basal area BA (m2, summed over all stems of a multi-stemmed tanoak). Here BA is written as pi/4 * (DBH/100)^2, so D is the dbh of a single stem; for multi-stemmed trees use the summed basal area instead. Output is belowground biomass excluding stump, in kg. r2 is the adjusted R2 as printed. The paper does not state a back-transformation correction factor, so none is applied. Other candidate models (with crown position, SDI, height) and the root:shoot models (arcsine transform, coefficients not legible in the text layer) were not added.

Source

Namm, B. H., & Berrill, J.-P. (2020). How do tree- and stand-level factors influence belowground biomass and carbon storage in tanoak (Notholithocarpus densiflorus)? The Forestry Chronicle, 96(1), 50–60.

doi:10.5558/tfc2020-007 · Open access · copy we read

n = 12 trees

Trees measured · Table 2 caption

the dbh of individual stems were between 1.9 cm and 52.4 cm

Smallest DBH · Results, p. 53

Tree heights ranged from 2.7 m to 21.1 m

h min m · Results, p. 53

0.9425

R² · Table 2, R2 adj. of the best-AICc model

Trees measured: 12
DBH range: 1.9–52.4 cm
Height range: 2.7–21.1 m
R²: 0.9425
Method: linear mixed model on ln scale (block random effect), excavated root systems
Where: L.W. Schatz Demonstration Tree Farm, Humboldt County, California
Last checked: 2026-11-02

Calculate

DBH (cm)

97.8

Root biomass (kg)

Carbon (kg), ×0.47

168

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 = 31.1	98	97.8	Value printed in the paper Results, p. 53: tanoak with average tree BA of 0.076 m2 (single-stemmed dbh 31.1 cm) expected to store 98 kg belowground (rounded in paper)
D = 15	29.8	29.8	Computed from the printed form computed from the published form (coefficients as printed)
D = 45	179	179	Computed from the printed form computed from the published form (coefficients as printed)

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