Tree Allometrics

Tsuga canadensis / Aboveground biomass, without leaves

NSVB eastern hemlock, Hot Continental Regime Mountains (M220): total aboveground biomass (without foliage), segmented model (Eq. 2), D < 9 in (22.86 cm)

Aboveground biomass, without leavesTsuga canadensis · PinaceaeUnited StatesRead from the original paper
Photo of Tsuga canadensis
© Ian Manning · CC BY · 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)

261,M220,,2,0.435207622,,2.125444089,2.041079911,0.547532483,

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

Aboveground biomass, without leaves = 0.45359237 * 0.435207622 * (D/2.54)^2.125444089 * (H/0.3048)^0.547532483
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 in M220 (table S19) 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. Lower branch of the segmented model; pair with westfall-2024-tsuga-canadensis-m220-agb-large.

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
261,eastern hemlock,N,Tsuga,canadensis,,,Tsuga canadensis
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
"Total Tree Wood+Bark","TT_WDBK_DW_ADJ","261","M220","HOT_CONTINENTAL_REGIME_MOUNTAINS",62,8.24032258064516,1.5,21.7
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
62
DBH range
3.81–22.86 cm
Method
NSVB segmented model (Eq. 2), coefficients for SPCD 261 in DIVISION M220 from table S8a; fitted with weighted regression to destructively sampled trees
Where
FIA ecodivision Hot Continental Regime Mountains (M220), mapped in GTR fig. 1
Last checked
2026-11-03
Calculate
Height from
71.5
Aboveground biomass, without leaves (kg)
33.6
Carbon (kg), ×0.47
123
CO₂e (kg), ×44/12
Fitted DBH range0100200300400500600510152025303540DBH (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 = 15.2, H = 13.771.571.5Computed from the printed form
computed from the published form at D = 6 in, H = 45 ft, converted to cm, m and kg

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