{"id":"santos-2020-manilkara-huberi","source":{"id":"santos-2020","citation":"Santos, M.F. dos, Figueiredo Filho, A., Gama, J.R.V., Retslaff, F.A. de S., Costa, D.L. da (2020). Species-specific equations: greater precision in commercial volume estimation in managed forests in the Amazon. CERNE, 26(3), 315-330.","title":"Species-specific equations: greater precision in commercial volume estimation in managed forests in the Amazon","authors":["Santos, M.F. dos","Figueiredo Filho, A.","Gama, J.R.V."],"year":2020,"venue":"CERNE","doi":"10.1590/01047760202026032741","url":"https://doi.org/10.1590/01047760202026032741","read_url":"https://www.scielo.br/j/cerne/a/wVP9VN9KTRZwBYfg8yngfPL/?lang=en&format=pdf","access":"open","checked_at":"2026-11-02","status":"current"},"name":"Commercial stem volume from DBH, Manilkara huberi (species-specific, Table 2)","output":{"quantity":"stem_volume"},"expression":"exp(-5.95341 + 1.76982 * ln(D))","published":{"expression":"exp(-5.95341 + 1.76982 * ln(DBH))","units":{"DBH":"cm"},"variables":{"DBH":"D"},"output_unit":"m3"},"taxon":{"level":"species","name":"Manilkara huberi","family":"Sapotaceae","group":"broadleaf"},"region":{"scope":"site","countries":["BR"],"place":"Tapajós National Forest, Pará (community forest management concession), eastern Brazilian Amazon","biomes":["tropical"]},"stand":"natural","fit":{"n_trees":6582,"dbh_min_cm":50,"r2":0.6,"method":"Model 2 (Husch) fitted by least squares on ln(vc); r2 is the adjusted R² recalculated in arithmetic units; Syx = 1.759 m3 (28.4%)"},"evidence":[{"field":"expression","quote":"M. huberi vc = exp(-5.95341 + 1.76982ln(DBH)) 0.60 1.759 28.4","locator":"Table 2, SSEs rows"},{"field":"fit.n_trees","quote":"Manilkara huberi (Ducke) A. Chev.  Maçaranduba  6,582  728","locator":"Table 1 (columns: adjustment, validation)"},{"field":"fit.dbh_min_cm","quote":"29,119 trees (50.0 cm ≤ DBH ≤ 175.0 cm) of 43 commercial species","locator":"Material and Methods, Data collection"},{"field":"output","quote":"composed the commercial volume (vc) of the stem","locator":"Material and Methods, Data collection"}],"check":[{"inputs":{"D":60},"expected":3.6431,"origin":"computed","note":"hand-computed from the Table 2 coefficients"},{"inputs":{"D":90},"expected":7.4666,"origin":"computed","note":"hand-computed from the Table 2 coefficients"},{"inputs":{"D":130},"expected":14.314,"origin":"computed","note":"hand-computed from the Table 2 coefficients"}],"verification":"original_read","checked_at":"2026-11-02","notes":"Species-specific equation (M. huberi, Maçaranduba). vc is the commercial volume of the stem (sum of Smalian log volumes, hollows discounted), not total tree volume. No back-transformation correction factor is stated, so none is applied. n_trees is the adjustment (fitting) set; DBH range is that of the whole dataset (all species), not stated per species. Ten percent of trees were held out for validation. 8 of the 36+1 species equations in Table 2 were added (the ten most important commercial species by harvested volume plus H. petraeum); the generic FMA equation was rejected by the authors' own paired t-test. The most important commercial species of the study."}