{"id":"westfall-2024-populus-deltoides-foliage","source":{"id":"westfall-2024","citation":"Westfall, J.A., Coulston, J.W., Gray, A.N., Shaw, J.D., Radtke, P.J., Walker, D.M., Weiskittel, A.R., et al. (2024). A national-scale tree volume, biomass, and carbon modeling system for the United States. Gen. Tech. Rep. WO-104. Washington, DC: USDA Forest Service. 37 p.","title":"A national-scale tree volume, biomass, and carbon modeling system for the United States","authors":["Westfall, J.A.","Coulston, J.W.","Gray, A.N."],"year":2024,"venue":"USDA Forest Service General Technical Report WO-104","doi":"10.2737/WO-GTR-104","url":"https://doi.org/10.2737/WO-GTR-104","read_url":"https://research.fs.usda.gov/download/treesearch/66998.pdf","access":"open","checked_at":"2026-11-03","status":"current","notes":"The National Scale Volume and Biomass (NSVB) framework. FIA's NSVB page (research.fs.usda.gov/programs/fia/nsvb) says the models were released in FIADB on 30 September 2023 and replace the former Component Ratio Method (CRM); the GTR itself still calls CRM the current implementation. Read: May 2024 GTR, slightly revised February 2026. Models are fitted by species (or species group) within FIA ecodivision, with D in inches at 4.5 ft, H in feet, output in cubic feet or pounds; four candidate model forms (Schumacher-Hall, segmented, continuously variable, modified Wiley), plus a modified Schumacher-Hall with wood specific gravity for Jenkins groups and a volume-ratio model. Coefficients live in supplemental CSV tables S1a–S9b (S10 holds carbon fractions, S11 crown ratios, S12–S20 fit statistics), file WO-GTR-104-Supp1.zip (doi:10.2737/WO-GTR-104-Supp1, which resolves to https://www.fs.usda.gov/research/publications/gtr/gtr_wo104/WO-GTR-104-Supp1.zip). Read from the official zip (sha256 8db6438f…c1808927), downloaded by hand from fs.usda.gov on 2026-11-03 because the site returns HTTP 403 to scripted requests. Captured from it: every species, genus and species-by-ecodivision row of tables S1a (total stem wood volume inside bark), S7a (branches), S8a (total AGB without foliage) and S9a (foliage), with n and DBH range from scorecards S13 and S19. Left out: the Jenkins-group tables (S1b–S9b, model 5 needs wood specific gravity per tree), bark, outside-bark and merchantable volume (S2–S5), bark biomass (S6), SPCD 999 (unknown tree), and division rows that repeat the species-level row exactly. The worked examples (Douglas-fir 240, red maple, white oak M220) keep the GTR's 12-digit coefficients, which round to the supplement's values; Example 2's red maple tree is in M210, but the supplement has no M210 red maple row, so those records are species-level. Third-party copies of the supplement tables on GitHub (mbrussell/NSVB, silvxlabs/nsvb) are rounded, some to 3 significant digits, and aren't the Forest Service file: tips only, no numbers taken from them. AGB here excludes foliage and is the gross 'AGBPredicted' before cull/broken-top reductions and harmonization with components."},"name":"NSVB eastern cottonwood, species-level (all ecodivisions): foliage biomass, Schumacher-Hall model (Eq. 1)","output":{"quantity":"foliage_biomass"},"expression":"0.45359237 * 21.73893596 * (D/2.54)^2.471001179 * (H/0.3048)^(-1.345104883)","published":{"expression":"21.73893596 * DBH^2.471001179 * HT^(-1.345104883)","units":{"DBH":"in","HT":"ft"},"variables":{"DBH":"D","HT":"H"},"output_unit":"lb"},"taxon":{"level":"species","name":"Populus deltoides","family":"Salicaceae","group":"broadleaf"},"region":{"scope":"national","countries":["US"],"place":"United States, species-level fit (NSVB uses it wherever table S9a has no row for the tree's ecodivision)","biomes":["subtropical"]},"fit":{"n_trees":76,"dbh_min_cm":4.06,"dbh_max_cm":66.29,"method":"NSVB Schumacher-Hall model (Eq. 1), coefficients for SPCD 742 (species-level row, no DIVISION) from table S9a; fitted with weighted regression to destructively sampled trees"},"evidence":[{"field":"expression","quote":"742,,,1,21.73893596,,2.471001179,,-1.345104883,","locator":"Table S9a (Table S9a_foliage_coefs_spcd.csv, WO-GTR-104-Supp1), columns SPCD,DIVISION,STDORGCD,model,a,a1,b,b1,c,c1"},{"field":"expression","quote":"yi = a × Di^b × Hi^c + εi","locator":"Eq. 1, p. 2"},{"field":"published.units","quote":"Di is diameter (inches) at breast height (4.5 feet), Hi is total tree height (feet)","locator":"Methods, Model development, p. 2"},{"field":"published.output_unit","quote":"units for volume and biomass predictions are cubic feet and pounds, respectively","locator":"Examples of tree-level calculations, p. 8"},{"field":"taxon","quote":"742,eastern cottonwood,N,Populus,deltoides,,,Populus deltoides","locator":"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"},{"field":"region","quote":"If a species occurs in an ecodivision not explicitly listed, the entry having no ecodivision noted is used.","locator":"Results, p. 6"},{"field":"fit","quote":"\"Foliage\",\"FOL_DW\",\"742\",76,7.37236842105263,1.6,26.1","locator":"Table S13_component_spcd_scorecard.csv (WO-GTR-104-Supp1), columns VAR2,VAR3,SPCD,N,Avg_DBH,Min_DBH,Max_DBH"},{"field":"fit","quote":"key modeling statistics such as sample sizes (n), tree diameter distributions (minimum, mean, and maximum)","locator":"Methods, Model development, p. 6"}],"check":[{"inputs":{"D":30.48,"H":21.336},"expected":15.0908,"origin":"computed","note":"computed from the published form at D = 12 in, H = 70 ft, converted to cm, m and kg"}],"verification":"original_read","checked_at":"2026-11-03","notes":"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. Table S9a also lists these exact coefficients under DIVISION 230; this record stands for that row too."}