{"id":"chojnacky-2014-abies-spg-ge-035","source":{"id":"chojnacky-2014","citation":"Chojnacky, D.C., Heath, L.S., Jenkins, J.C. (2014). Updated generalized biomass equations for North American tree species. Forestry, 87(1), 129–151.","title":"Updated generalized biomass equations for North American tree species","authors":["Chojnacky, D.C.","Heath, L.S.","Jenkins, J.C."],"year":2014,"venue":"Forestry: An International Journal of Forest Research","doi":"10.1093/forestry/cpt053","url":"https://doi.org/10.1093/forestry/cpt053","read_url":"https://research.fs.usda.gov/download/treesearch/45402.pdf","access":"open","checked_at":"2026-11-01","status":"current"},"name":"North American taxa group: Abies ≥ 0.35 spg (Table 5)","output":{"quantity":"agb"},"expression":"exp(-3.1774 + 2.6426 * ln(D))","published":{"expression":"exp(-3.1774 + 2.6426 * ln(dbh))","units":{"dbh":"cm"},"variables":{"dbh":"D"},"output_unit":"kg"},"taxon":{"level":"mixed","name":"Abies ≥ 0.35 spg (A. amabilis, A. concolor, A. grandis, A. magnifica, A. procera, Abies spp.)","family":"Pinaceae","group":"conifer","members":["Abies amabilis","Abies concolor","Abies grandis","Abies magnifica","Abies procera"],"members_complete":false},"region":{"scope":"national","countries":["US"],"place":"United States (equations compiled from US and Canadian studies)","biomes":["temperate"]},"stand":"mixed","fit":{"dbh_min_cm":3,"dbh_max_cm":236,"r2":0.75,"method":"Weighted regression of ln(biomass) on ln(dbh) fitted to 221 pseudodata points generated from 14 published equations; no back-transform correction"},"evidence":[{"field":"expression","quote":"ln(biomass) = β0 + β1 ln(diameter)","locator":"Table 5 caption, p. 140"},{"field":"expression","quote":"Abies ≥ 0.35 spg 0.37 −3.1774 2.6426 221 14 dbh 3–236 0.75","locator":"Table 5 row, p. 140"},{"field":"taxon","quote":"A. amabilis Fir, Pacific silver 11 0.40 4","locator":"Table 2, p. 135"},{"field":"fit.cf","quote":"we did not include a correction (Baskerville, 1972) for underestimation","locator":"Methods, p. 139"}],"check":[{"inputs":{"D":30},"expected":333.8208,"origin":"computed","note":"computed from the published form at dbh = 30 cm"}],"verification":"original_read","checked_at":"2026-11-03","notes":"Western firs of higher specific gravity. The group also took equations for 'Abies spp.' (Pacific silver–noble–other firs). Median specific gravity of the group: 0.37. Diameter range is that of the pseudodata. R² is the published 'R²-statistic'."}