{"id":"westfall-2024-quercus-alba-m220-large","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":"2026-11-01","status":"current","notes":"The National Scale Volume and Biomass (NSVB) framework, adopted by FIA as the current US standard for tree volume, biomass and carbon (replacing the Component Ratio Method built on Jenkins et al. 2003). 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 pounds; four model forms (Schumacher-Hall, segmented, continuously variable, modified Wiley). Coefficients live in supplemental CSV tables S1a–S11 (doi:10.2737/WO-GTR-104-Supp1), which we could not download (fs.usda.gov returned HTTP 403 to scripted requests). Only the white oak AGB model printed in full in Example 4 is captured here; other target species (loblolly pine SPCD 131, which has separate planted/natural fits; yellow-poplar; sweetgum; red oak) need table S8a. AGB here excludes foliage and is the gross 'AGBPredicted' before cull/broken-top reductions and harmonization with components."},"name":"NSVB white oak, Hot Continental Mountains (M220), segmented model, D ≥ 11 in (27.94 cm)","output":{"quantity":"agb","excludes":["foliage"]},"expression":"0.45359237 * 0.024470323124 * 11^(1.93799905037 - 1.886819489967) * (D/2.54)^1.886819489967 * (H/0.3048)^1.403264431619","published":{"expression":"0.024470323124 * 11^(1.93799905037 - 1.886819489967) * DBH^1.886819489967 * HT^1.403264431619","units":{"DBH":"in","HT":"ft"},"variables":{"DBH":"D","HT":"H"},"output_unit":"lb"},"taxon":{"level":"species","name":"Quercus alba","family":"Fagaceae","group":"broadleaf"},"region":{"scope":"regional","countries":["US"],"place":"FIA ecodivision M220, Hot Continental Mountains (Appalachian/Ozark highlands)","biomes":["temperate","montane"]},"stand":"mixed","fit":{"dbh_min_cm":27.94,"method":"NSVB segmented model (Eq. 2), coefficients for SPCD 802 in DIVISION M220 from table S8a, as printed in Example 4; nonlinear fit to destructively sampled legacy and new tree data"},"evidence":[{"field":"expression","quote":"AGBPredicted = 0.024470323124 × 11^(1.93799905037 – 1.886819489967) × 18.1^1.886819489967 × 65^1.403264431619 = 2285.319903933610","locator":"Example 4, p. 24"},{"field":"taxon","quote":"a live white oak (Quercus alba; SPCD = 802) tree having D = 18.1 inches, H = 65 feet","locator":"Example 4, p. 21"},{"field":"region","quote":"growing in the Hot Continental Mountains (DIVISION = M220)","locator":"Example 4, p. 21"},{"field":"expression","quote":"k is a set segmentation point that is 9.0 inches for softwoods (SPCD<300) and 11.0 inches for hardwoods (SPCD≥300)","locator":"Methods, Model development, p. 2"},{"field":"published.units","quote":"Di is diameter (inches) at breast height (4.5 feet), Hi is total tree height (feet)","locator":"Methods, p. 2"},{"field":"expression","quote":"yi = a × k^(b−b1) × Di^b1 × Hi^c + εi; Di ≥ k","locator":"Eq. 2, p. 2"}],"check":[{"inputs":{"D":45.974,"H":19.812},"expected":1036.6037,"origin":"published","note":"Example 4 (p. 24) prints AGBPredicted = 2285.319903933610 lb for D = 18.1 in, H = 65 ft; inputs and expected converted to cm, m, kg"}],"verification":"original_read","checked_at":"2026-11-01","notes":"Upper branch of the segmented model (valid for D ≥ 11 in = 27.94 cm); pair with westfall-2024-quercus-alba-m220-small below that. dbh_min_cm is the segmentation point, not a data range. Output is gross AGB excluding foliage, before NSVB's cull/broken-top reductions and harmonization with stem/bark/branch components. Coefficients are those printed in the GTR's worked example; other ecodivisions use different coefficients (table S8a). Paper units: in, ft, lb; expression converts D cm→in (/2.54), H m→ft (/0.3048) and lb→kg (×0.45359237)."}