{"id":"westfall-2024-acer-rubrum-volume","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 red maple, species-level: total stem wood volume (inside bark), Schumacher-Hall model (Eq. 1)","output":{"quantity":"stem_volume"},"expression":"0.028316846592 * 0.001983918881 * (D/2.54)^1.810559393287 * (H/0.3048)^1.129417635145","published":{"expression":"0.001983918881 * DBH^1.810559393287 * HT^1.129417635145","units":{"DBH":"in","HT":"ft"},"variables":{"DBH":"D","HT":"H"},"output_unit":"ft3"},"taxon":{"level":"species","name":"Acer rubrum","family":"Sapindaceae","group":"broadleaf"},"region":{"scope":"national","countries":["US"],"place":"United States: red maple's species-level stem volume fit across ecodivisions, which NSVB uses wherever table S1a has no row for the tree's ecodivision","biomes":["temperate","subtropical"]},"fit":{"n_trees":3068,"dbh_min_cm":2.54,"dbh_max_cm":106.17,"method":"NSVB Schumacher-Hall model (Eq. 1), coefficients for SPCD 316, species-level row (no DIVISION) from table S1a (the total stem wood volume (inside bark) table used in Example 2); fitted with weighted regression to destructively sampled trees"},"evidence":[{"field":"expression","quote":"VtotibGross = 0.001983918881 × 11.1^1.810559393287 × 38^1.129417635145 = 9.427112777611","locator":"Example 2, p. 12"},{"field":"taxon","quote":"Assume a red maple (Acer rubrum; SPCD = 316)","locator":"Example 2, p. 12"},{"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":"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":"output","quote":"total stem was defined as groundline to tree tip","locator":"Methods, Data, p. 2"},{"field":"fit","quote":"\"Total Stem Wood Volume\",\"ST_WD_CV_TOT\",\"316\",3068,9.40677966101695,1,41.8","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":28.194,"H":11.5824},"expected":0.2669,"origin":"published","note":"Example 2 (p. 12) prints 9.427112777611 ft3 for D = 11.1 in, H = 38 ft; inputs and expected converted to cm, m, m3"}],"verification":"original_read","checked_at":"2026-11-03","notes":"Output is gross total stem wood volume inside bark, groundline to tip (VtotibGross), before cull or broken-top deductions. Species-level coefficients (no ecodivision): Example 2 says table S1a has no red maple row for its division (M210), so the species-level row applies. NSVB uses division-specific coefficients where table S1a has a row for the tree's division. Paper units: in, ft, ft3; expression converts D cm→in (/2.54), H m→ft (/0.3048) and ft3→m3 (×0.028316846592). n and the DBH range are from the scorecard for ST_WD_CV_TOT across ecodivisions (table S13). DBH is measured at 4.5 ft (1.37 m)."}