{"id":"chave-2014-eq7","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 without height, with stress index E (Eq. 7)","output":{"quantity":"agb"},"expression":"exp(-1.803 - 0.976 * E + 0.976 * ln(rho) + 2.673 * ln(D) - 0.0299 * (ln(D))^2)","published":{"expression":"exp(-1.803 - 0.976 * E + 0.976 * ln(rho) + 2.673 * ln(D) - 0.0299 * (ln(D))^2)","units":{"D":"cm","rho":"g/cm3","E":"unitless"},"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":0.413,"method":"log-scale regression on E, ln(ρ), ln(D), ln(D)²"},"evidence":[{"field":"expression","quote":"AGBest = exp[−1.803 − 0.976E + 0.976 ln(ρ) + 2.673 ln(D) − 0.0299[ln(D)]²]","locator":"Eq. 7, p. 3183"},{"field":"fit.rse","quote":"(AIC = 4293, σ = 0.413, df = 3999)","locator":"Eq. 7, p. 3183"},{"field":"notes","quote":"We therefore propose Model 7 for estimating AGB in the absence of height measurements.","locator":"Results, p. 3183"},{"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,"rho":0.6,"E":0},"expected":628.88,"origin":"computed","note":"computed with python3 from the published form"},{"inputs":{"D":30,"rho":0.6,"E":0.5},"expected":386.04,"origin":"computed","note":"computed with python3 from the published form"}],"verification":"original_read","checked_at":"2026-11-01","notes":"Use when height is not measured. E from Eq. 6b / the authors' gridded layer. Printed as AGBest under the paper's Eq. 2 convention (estimator includes exp(σ²/2)); no further correction applied. Note: the BIOMASS R package uses refitted coefficients for this model, not these printed ones."}