Tree Allometrics

Abies balsamea / Aboveground biomass, without leaves

NSVB balsam fir, species-level (all ecodivisions): total aboveground biomass (without foliage), segmented model (Eq. 2), D ≥ 9 in (22.86 cm)

Aboveground biomass, without leavesAbies balsamea · PinaceaeUnited StatesRead from the original paper
Photo of Abies balsamea
© Douglas Goldman · CC BY-SA · iNaturalist
Equation

As printed (Table S8a (Table S8a_total_biomass_coefs_spcd.csv, WO-GTR-104-Supp1), columns SPCD,DIVISION,STDORGCD,model,a,a1,b,b1,c,c1)

12,,,2,0.328136654,,2.068856431,2.178341624,0.600282409,

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

Aboveground biomass, without leaves = 0.45359237 * 0.328136654 * 9^(2.068856431 - 2.178341624) * (D/2.54)^2.178341624 * (H/0.3048)^0.600282409
D
Diameter at breast height (1.3 m), cm
H
Total tree height, m

Output is gross AGB without foliage (AGBPredicted), before NSVB's cull and broken-top reductions and harmonization with components. DBH is measured at 4.5 ft (1.37 m). 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 TT_WDBK_DW_ADJ across ecodivisions (table S13) and cover the whole segmented model; the record's DBH limit at k is the segmentation point. For AGB the scorecard rates NSVB's harmonized total (TT_WDBK_DW_ADJ), not this model alone; only its n and DBH range are used. Upper branch of the segmented model; pair with westfall-2024-abies-balsamea-agb-small. Species-level row: NSVB applies it in every ecodivision that has no row of its own for this species in this table.

Source
yi = a × Di^b × Hi^c + εi; Di < k / yi = a × k^(b−b1) × Di^b1 × Hi^c + εi; Di ≥ k
Equation · Eq. 2, 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
12,balsam fir,N,Abies,balsamea,,,Abies balsamea
Taxon · FIADB REF_SPECIES.csv (FIA DataMart), columns SPCD,COMMON_NAME,SHARED_COMMON_NAME_IND,GENUS,SPECIES,VARIETY,SUBSPECIES,SCIENTIFIC_NAME: the species codes the NSVB tables use
total aboveground biomass (without foliage)
output.excludes · Methods, Model development, p. 4
k is a set segmentation point that is 9.0 inches for softwoods (SPCD<300) and 11.0 inches for hardwoods (SPCD≥300)
Equation · Methods, Model development, p. 2
If a species occurs in an ecodivision not explicitly listed, the entry having no ecodivision noted is used.
Where · Results, p. 6
"Total Tree Wood+Bark","TT_WDBK_DW_ADJ","12",117,5.67350427350427,1,16
Fit · Table S13_component_spcd_scorecard.csv (WO-GTR-104-Supp1), columns VAR2,VAR3,SPCD,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
117
DBH range
22.86–40.64 cm
Method
NSVB segmented model (Eq. 2), coefficients for SPCD 12 (species-level row, no DIVISION) from table S8a; fitted with weighted regression to destructively sampled trees
Where
United States, species-level fit (NSVB uses it wherever table S8a has no row for the tree's ecodivision)
Last checked
2026-11-03
Calculate
Height from
614
Aboveground biomass, without leaves (kg)
289
Carbon (kg), ×0.47
1,059
CO₂e (kg), ×44/12
Fitted DBH range05001,0001,5002,0002,5003,00010203040506070DBH (cm)Aboveground biomass, without leaves (kg)Aboveground biomass, without leaves

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 = 38.1, H = 25.9614614Computed from the printed form
computed from the published form at D = 15 in, H = 85 ft, converted to cm, m and kg

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