Equations / Foliage biomass
NSVB willow spp., species-level (all ecodivisions): foliage biomass, Schumacher-Hall model (Eq. 1)
As printed (Table S9a (Table S9a_foliage_coefs_spcd.csv, WO-GTR-104-Supp1), columns SPCD,DIVISION,STDORGCD,model,a,a1,b,b1,c,c1)
In this library's units, ready to compute (kg)
Foliage biomass = 0.45359237 * 0.682168963 * (D/2.54)^2.081875867 * (H/0.3048)^(-0.485308401)D- Diameter at breast height (1.3 m), cm
H- Total tree height, m
FIA's SPCD 920 (Salix spp.) is for trees recorded only to genus, so this is a genus record. 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 FOL_DW across ecodivisions (table S13). Species-level row: NSVB applies it in every ecodivision that has no row of its own for this species in this table.
doi:10.2737/WO-GTR-104 · Open access · copy we read
yi = a × Di^b × Hi^c + εi
Di is diameter (inches) at breast height (4.5 feet), Hi is total tree height (feet)
units for volume and biomass predictions are cubic feet and pounds, respectively
920,willow spp.,N,Salix,spp.,,,Salix spp.
If a species occurs in an ecodivision not explicitly listed, the entry having no ecodivision noted is used.
"Foliage","FOL_DW","920",7,4.07142857142857,1.3,10.1
key modeling statistics such as sample sizes (n), tree diameter distributions (minimum, mean, and maximum)
- Trees measured
- 7
- DBH range
- 3.3–25.65 cm
- Method
- NSVB Schumacher-Hall model (Eq. 1), coefficients for SPCD 920 (species-level row, no DIVISION) from table S9a; fitted with weighted regression to destructively sampled trees
- Where
- United States, species-level fit (NSVB uses it wherever table S9a has no row for the tree's ecodivision)
- Last checked
- 2026-11-03
Shaded: the DBH range the model was fitted on. Other inputs held at the values above.
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 = 14.5, H = 21.3 | 1.47 | 1.47 | Computed from the printed form computed from the published form at D = 5.7 in, H = 70 ft, converted to cm, m and kg |
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