Tree Allometrics

Pseudotsuga menziesii / Branch biomass

NSVB Douglas-fir, Marine Division (240): total branch biomass (wood and bark), Schumacher-Hall model (Eq. 1)

Branch biomassPseudotsuga menziesii · PinaceaeUnited StatesRead from the original paper
Photo of Pseudotsuga menziesii
© Danny Steaven · CC BY-SA · iNaturalist
Equation

As printed (Example 1, p. 11)

Wbranch = 9.521330809106 × 20^1.762316117442 × 110^-0.40574259177 = 277.487756904646

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

Branch biomass = 0.45359237 * 9.521330809106 * (D/2.54)^1.762316117442 * (H/0.3048)^-0.40574259177
D
Diameter at breast height (1.3 m), cm
H
Total tree height, m

Output is dry weight of all branch wood and bark (Wbranch) before NSVB's harmonization with total AGB; the harmonized branch weight differs. Coefficients for Douglas-fir in the Marine Division (240) only; NSVB uses other coefficients for Douglas-fir elsewhere (tables S1a–S9a). Paper units: in, ft, lb; expression converts D cm→in (/2.54), H m→ft (/0.3048) and lb→kg (×0.45359237). n and the DBH range are from the scorecard for BRT_WDBK_DW_TOT in 240 (table S19). DBH is measured at 4.5 ft (1.37 m).

Source
a Douglas-fir (Pseudotsuga menziesii; SPCD = 202)
Taxon · Example 1, p. 8
growing in the Marine Division (DIVISION = 240)
Where · Example 1, p. 8
yi = a × Di^b × Hi^c + εi
Equation · Eq. 1, p. 2
Di is diameter (inches) at breast height (4.5 feet), Hi is total tree height (feet)
Units · Methods, Model development, p. 2
units for volume and biomass predictions are cubic feet and pounds, respectively
published.output unit · Examples of tree-level calculations, p. 8
total branch wood and bark biomass
Output · Methods, Model development, p. 4
"Branches","BRT_WDBK_DW_TOT","202","240","MARINE_DIVISION",63,14.2492063492063,3.6,44.9
Fit · Table S19_component_division_spcd_scorecard.csv (WO-GTR-104-Supp1), columns VAR2,VAR3,SPCD,DIVISION,DIVISION_DESCRIPTION,N,Avg_DBH,Min_DBH,Max_DBH
key modeling statistics such as sample sizes (n), tree diameter distributions (minimum, mean, and maximum)
Fit · Methods, Model development, p. 6
Trees measured
63
DBH range
9.14–114.05 cm
Method
NSVB Schumacher-Hall model (Eq. 1), coefficients for SPCD 202 in DIVISION 240 from table S7a (the total branch biomass (wood and bark) table used in Example 1); fitted with weighted regression to destructively sampled trees
Where
FIA ecodivision Marine Division (240), mapped in GTR fig. 1
Last checked
2026-11-03
Calculate
Height from
126
Branch biomass (kg)
59.2
Carbon (kg), ×0.47
217
CO₂e (kg), ×44/12
Fitted DBH range010020030040050020406080100DBH (cm)Branch biomass (kg)Branch biomass

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%.

InputsExpectedWe getFrom
D = 50.8, H = 33.5126126Value printed in the paper
Example 1 (p. 11) prints 277.487756904646 lb for D = 20 in, H = 110 ft; inputs and expected converted to cm, m, kg

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