{"id":"chojnacky-2014-betulaceae-spg-050-059","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: Betulaceae 0.50–0.59 spg (Table 5)","output":{"quantity":"agb"},"expression":"exp(-1.8096 + 2.3480 * ln(D))","published":{"expression":"exp(-1.8096 + 2.3480 * ln(dbh))","units":{"dbh":"cm"},"variables":{"dbh":"D"},"output_unit":"kg"},"taxon":{"level":"species","name":"Betula alleghaniensis","family":"Betulaceae","group":"broadleaf"},"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":70,"r2":0.81,"method":"Weighted regression of ln(biomass) on ln(dbh) fitted to 134 pseudodata points generated from 16 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":"Betulaceae 0.50–0.59 spg 0.55 −1.8096 2.3480 134 16 dbh 3–70 0.81","locator":"Table 5 row, p. 140"},{"field":"taxon","quote":"Betulaceae B. alleghaniensis Birch, yellow 371 0.55","locator":"Table 3, p. 136"},{"field":"fit.cf","quote":"we did not include a correction (Baskerville, 1972) for underestimation","locator":"Methods, p. 139"}],"check":[{"inputs":{"D":30},"expected":481.2618,"origin":"computed","note":"computed from the published form at dbh = 30 cm"}],"verification":"original_read","checked_at":"2026-11-03","notes":"Fitted for the Betulaceae 0.50–0.59 spg taxon, which held only yellow birch equations, so it is recorded as a species fit. Median specific gravity of the group: 0.55. Diameter range is that of the pseudodata. R² is the published 'R²-statistic'."}