{"id":"koirala-2017-v-dbh","source":{"id":"koirala-2017","citation":"Koirala, A., Kizha, A. R., & Baral, S. (2017). Modeling height-diameter relationship and volume of teak (Tectona grandis L.f.) in central lowlands of Nepal. Journal of Tropical Forestry and Environment, 7(1), 28–42.","title":"Modeling Height-Diameter Relationship and Volume of Teak (Tectona grandis L.f.) in Central Lowlands of Nepal","authors":["Koirala, A.","Kizha, A. R.","Baral, S."],"year":2017,"venue":"Journal of Tropical Forestry and Environment","doi":"10.31357/jtfe.v7i1.3020","url":"https://doi.org/10.31357/jtfe.v7i1.3020","read_url":"https://web.archive.org/web/2024/http://journals.sjp.ac.lk/index.php/JTFE/article/download/3020/2093","access":"open","checked_at":"2026-11-02","status":"current"},"name":"Teak stem volume from D (V1, local)","output":{"quantity":"stem_volume"},"expression":"-0.4720 + 0.0414 * D","published":{"expression":"-0.4720 + 0.0414 * dbh","units":{"dbh":"cm"},"variables":{"dbh":"D"},"output_unit":"m3"},"taxon":{"level":"species","name":"Tectona grandis","family":"Lamiaceae","group":"broadleaf"},"region":{"scope":"site","countries":["NP"],"place":"Sagarnath Forestry Development Project, Sarlahi district, central lowland Nepal","biomes":["tropical"]},"stand":"plantation","fit":{"n_trees":31,"dbh_min_cm":6.37,"dbh_max_cm":58.92,"h_min_m":5.7,"h_max_m":26.1,"r2":0.949,"method":"least squares on training set (31 of 44 felled trees)"},"evidence":[{"field":"expression","quote":"V = a + b × (dbh) ... a -0.4720, b 0.0414","locator":"Table 6 (form V1), Table 7 (estimates)"},{"field":"fit.n_trees","quote":"31 (70 % of the data) were randomly selected to build the model","locator":"Section 2.2"}],"check":[{"inputs":{"D":20},"expected":0.356,"origin":"computed","note":"computed from the published form (coefficients as printed); not meaningful below about 11.4 cm (negative volume)"},{"inputs":{"D":35},"expected":0.977,"origin":"computed","note":"computed from the published form (coefficients as printed); not meaningful below about 11.4 cm (negative volume)"},{"inputs":{"D":55},"expected":1.805,"origin":"computed","note":"computed from the published form (coefficients as printed); not meaningful below about 11.4 cm (negative volume)"}],"verification":"original_read","checked_at":"2026-11-02","notes":"Volume is the total stem volume above the 0.10 m stump (stump excluded), summed from log sections and the tree top. Paper calls V1 the local volume equation. R2 0.949 (adj. 0.944), RMSE 0.20 m3 (Table 7). Predicts negative volume for small trees."}