{"id":"baia-2025-terra-firme-quadratic","source":{"id":"baia-2025","citation":"Baia, A.L.P., Nascimento, H.E.M., Guedes, M., Hilário, R., Toledo, J.J. (2025). Tree height-diameter allometry and implications for biomass estimates in Northeastern Amazonian forests. PeerJ, 13, e18974.","title":"Tree height-diameter allometry and implications for biomass estimates in Northeastern Amazonian forests","authors":["Baia, A.L.P.","Nascimento, H.E.M.","Guedes, M."],"year":2025,"venue":"PeerJ","doi":"10.7717/peerj.18974","url":"https://doi.org/10.7717/peerj.18974","read_url":"https://europepmc.org/article/MED/40093411","access":"open","license":"Creative Commons Attribution License","checked_at":"2026-11-02","status":"current","notes":"Read the full text and tables via Europe PMC (PMC11908443); the publisher site blocks scripts. Height-diameter models, not biomass. Seven of the ten candidate models in Table 2 are captured (the best ones per forest type and for both forests pooled). The RSE in Table 2 is on the height scale (m), not log scale."},"name":"Height from DBH, Quadratic model, terra-firme","output":{"quantity":"height"},"expression":"exp(0.63296 + 1.11213 * ln(D) - 0.09504 * ln(D)^2)","published":{"expression":"exp(0.63296 + 1.11213 * ln(DBH) - 0.09504 * ln(DBH)^2)","units":{"DBH":"cm"},"variables":{"DBH":"D"},"output_unit":"m"},"taxon":{"level":"mixed","name":"Mixed Amazonian forest trees (367 species in terra-firme, 65 in várzea)","group":"mixed"},"region":{"scope":"site","countries":["BR"],"place":"Non-flooded terra-firme forest, National Forest of Amapá (NFA), Brazil","biomes":["tropical"]},"stand":"natural","fit":{"n_trees":1156,"dbh_min_cm":1,"dbh_max_cm":109.1,"h_min_m":1.2,"h_max_m":51.9,"r2":0.87,"method":"nonlinear least squares height-diameter model; R2 is the adjusted pseudo R2"},"evidence":[{"field":"expression","quote":"H = exp(a + b × ln(DBH) + c × ln(DBH)²) + ε ; Table 2: Quadratic a 0.63296 0.081 4.018 0.87 6,501.2 | b 1.11213 0.052 | c −0.09504 0.008","locator":"Table 1 (form) and Table 2, Terra-firme block"},{"field":"fit.n_trees","quote":"We sampled 1,156 trees of 367 species ... in the terra-firme sites, and 806 trees of 65 species ... in várzea","locator":"Abstract"},{"field":"fit.dbh_min_cm","quote":"In the terra-firme sites, trees ranged from 1 to 109.1 cm DBH and 1.2 to 51.9 m in total height. In várzea sites, trees ranged from 5 to 139.5 cm DBH and 2.3 to 38.8 m in total height.","locator":"Results, first paragraph"},{"field":"fit.r2","quote":"Adj. pseudo R2 0.87","locator":"Table 2, Terra-firme block"}],"check":[{"inputs":{"D":10},"expected":14.729,"origin":"computed","note":"computed from the published form (coefficients as printed)"},{"inputs":{"D":30},"expected":27.553,"origin":"computed","note":"computed from the published form (coefficients as printed)"},{"inputs":{"D":60},"expected":36.35,"origin":"computed","note":"computed from the published form (coefficients as printed)"}],"verification":"original_read","checked_at":"2026-11-02","notes":"Predicts total tree height from DBH. The quadratic form is read as a + b ln(DBH) + c (ln DBH)^2 inside exp(); Table 1 prints ln(DBH) with a superscript 2, and ln(DBH^2) would not be separable from the b term. RSE printed in Table 2 is 4.018 (height scale, m), so fit.rse is not stored. Ranges are those printed for the trees sampled in this forest type. No correction factor is applied; the paper reports local models deviate 0.1% from measured heights."}