{"id":"das-2026-sb6-hybrid","source":{"id":"das-2026","citation":"Das, N., Chowdhury, M.Q. (2026). Stump diameter is a robust predictor of biomass and carbon stocks in tropical Acacia plantations. Discover Forests, 2, 73.","title":"Stump diameter is a robust predictor of biomass and carbon stocks in tropical Acacia plantations","authors":["Das, N.","Chowdhury, M.Q."],"year":2026,"venue":"Discover Forests","doi":"10.1007/s44415-026-00137-1","url":"https://doi.org/10.1007/s44415-026-00137-1","read_url":"https://link.springer.com/article/10.1007/s44415-026-00137-1","access":"open","checked_at":"2026-11-02","status":"current"},"name":"Acacia auriculiformis × Acacia mangium (hybrid) plantation, stem biomass from stump diameter (SB6)","output":{"quantity":"stem_biomass"},"expression":"1.0217 * exp(-2.426 + 2.205 * ln(D30))","published":{"expression":"1.0217 * exp(-2.426 + 2.205 * ln(dst))","units":{"dst":"cm"},"variables":{"dst":"D30"},"output_unit":"kg"},"taxon":{"level":"species","name":"Acacia auriculiformis × Acacia mangium (hybrid)","group":"broadleaf"},"region":{"scope":"site","countries":["BD"],"place":"Ten plantation sites, Sylhet Division, Bangladesh","biomes":["tropical"]},"stand":"plantation","fit":{"n_trees":25,"r2":0.9546,"cf":1.0217,"method":"OLS on ln-transformed data (ln-ln), adjusted R2"},"evidence":[{"field":"expression","quote":"SB6 Hybrid −2.426*** 2.205*** 0.207 4186 0.9546 −57.95 17.266 1.0217 2.031","locator":"Table 3, model SB6 (columns: β0, β1, RMSE, F, adjusted R2, AIC, average deviation, CF, DW)"},{"field":"expression","quote":"The ln–ln stump-based model (SB6) was parsimonious and produced adjusted R2 values of 0.945–0.968 across species","locator":"Section 3.3"},{"field":"published.units","quote":"stump diameter (dst, measured at 30 cm above ground)","locator":"Abstract"},{"field":"output","quote":"Biomass estimates refer specifically to stem biomass; branch, foliage, and root components were not included.","locator":"Section 2.4"},{"field":"fit.n_trees","quote":"Calibration models were developed using 75 destructively sampled trees (25 per species, covering small, medium and large diameter classes)","locator":"Section 2.2"},{"field":"fit.method","quote":"All log transformations used natural logs (ln).","locator":"Section 2.5"}],"check":[{"inputs":{"D30":30},"expected":163.22,"origin":"computed","note":"hand-computed from the published form"},{"inputs":{"D30":50},"expected":503.45,"origin":"computed","note":"hand-computed from the published form"}],"verification":"original_read","checked_at":"2026-11-02","notes":"Stem biomass only (bark included, oven-dry), so output is stem_biomass not agb. Form read as ln(SB) = β0 + β1 ln(dst) from the text calling SB6 the \"ln–ln stump-based model\"; the full model list is in a supplementary Table S1 that was not read. The Table 3 CF (1.0217) is applied in both forms. Table 3 caption says RMSE is in kg but the body values (about 0.2) are log-scale (CF 1.0193 matches exp(0.196²/2)), so the body is followed and rse is not stored. Table 3 gives no DBH range for the 25 calibration trees, so none is stored. Row label \"Hybrid\" in Table 3 maps to this taxon."}