{"id":"chave-2014-eq6a","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 height–diameter model with stress index E (Eq. 6a)","output":{"quantity":"height"},"expression":"exp(0.893 - E + 0.760 * ln(D) - 0.0340 * (ln(D))^2)","published":{"expression":"exp(0.893 - E + 0.760 * ln(D) - 0.0340 * (ln(D))^2)","units":{"D":"cm","E":"unitless"},"output_unit":"m"},"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":{"dbh_min_cm":5,"dbh_max_cm":212,"rse":0.243,"method":"linear regression of ln(H) on E, ln(D) and ln(D)²"},"evidence":[{"field":"expression","quote":"ln(H) = 0.893 − E + 0.760 ln(D) − 0.0340[ln(D)]²","locator":"Eq. 6a, p. 3183"},{"field":"fit.rse","quote":"(AIC = 47, RSE = 0.243, df = 3998)","locator":"Eq. 6a, p. 3183"},{"field":"notes","quote":"E = (0.178 × TS − 0.938 × CWD − 6.61 × PS) × 10⁻³","locator":"Eq. 6b, p. 3183"},{"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,"E":0},"expected":21.86,"origin":"computed","note":"computed with python3 from the published form"},{"inputs":{"D":30,"E":0.5},"expected":13.26,"origin":"computed","note":"computed with python3 from the published form"}],"verification":"original_read","checked_at":"2026-11-01","notes":"E is the bioclimatic stress index of Eq. 6b (TS temperature seasonality, CWD climatic water deficit, PS precipitation seasonality); a global gridded E layer is published by the authors. The paper prints the model on the log scale and gives no back-transform correction for H; expression is the plain exp() of Eq. 6a. Fitted on the harvest dataset (df = 3998); the paper does not state n separately for this fit."}