{"id":"chave-2014-eq4","source":{"id":"chave-2014","citation":"Chave, J., Réjou-Méchain, M., Búrquez, A., et al. (2014). Improved allometric models to estimate the aboveground biomass of tropical trees. Global Change Biology, 20(10), 3177–3190.","title":"Improved allometric models to estimate the aboveground biomass of tropical trees","authors":["Chave, J.","Réjou-Méchain, M.","Búrquez, A."],"year":2014,"venue":"Global Change Biology","doi":"10.1111/gcb.12629","url":"https://doi.org/10.1111/gcb.12629","read_url":"https://forestgeo.si.edu/sites/default/files/aboveground_biomass_protocol_accessible.pdf","access":"paywalled","checked_at":"2026-11-01","status":"current"},"name":"Pantropical AGB with height (Eq. 4)","output":{"quantity":"agb"},"expression":"0.0673 * (rho * D^2 * H)^0.976","published":{"expression":"0.0673 * (rho * D^2 * H)^0.976","units":{"D":"cm","H":"m","rho":"g/cm3"},"output_unit":"kg"},"taxon":{"level":"mixed","name":"Tropical trees (58 sites)","group":"broadleaf"},"region":{"scope":"pantropical","countries":[],"place":"58 harvest sites across the tropics","biomes":["tropical","subtropical","dryland"]},"stand":"natural","fit":{"n_trees":4004,"dbh_min_cm":5,"dbh_max_cm":212,"rse":0.357,"method":"log-log linear regression of AGB on ρD²H"},"evidence":[{"field":"expression","quote":"AGBest = 0.0673 × (ρD²H)^0.976","locator":"Eq. 4, p. 3182"},{"field":"fit.rse","quote":"(σ = 0.357, AIC = 3130, df = 4002)","locator":"Eq. 4, p. 3182"},{"field":"published.units","quote":"where D is in cm, H is in m, and ρ is in g cm−3","locator":"Results, p. 3182"},{"field":"fit.n_trees","quote":"4004 trees ≥ 5 cm trunk diameter","locator":"Abstract, p. 3177"},{"field":"fit.dbh_max_cm","quote":"for a total of 4004 trees with trunk diameter ranging from 5 to 212 cm","locator":"Introduction, p. 3178"}],"check":[{"inputs":{"D":30,"H":25,"rho":0.6},"expected":723.14,"origin":"computed","note":"computed with python3 from the published form"}],"verification":"original_read","checked_at":"2026-11-01","notes":"Recommended by the authors when height is measured. The paper derives its estimator as AGBest = exp[σ²/2 + a + b ln(ρD²H)] (Eq. 2, Baskerville correction), so the printed coefficient is used as is; no further correction factor applied. The paper notes Model 4 underestimates AGB by about 20% for trees above 30 Mg. 53 undisturbed and 5 secondary-forest sites."}