{"id":"manyanda-2019-bgb-regional","source":{"id":"manyanda-2019","citation":"Manyanda, B.J., Mugasha, W.A., Nzunda, E.F., Malimbwi, R.E. (2019). Biomass and Volume Models Based on Stump Diameter for Assessing Degradation of Miombo Woodlands in Tanzania. International Journal of Forestry Research, 2019, 1876329.","title":"Biomass and Volume Models Based on Stump Diameter for Assessing Degradation of Miombo Woodlands in Tanzania","authors":["Manyanda, B.J.","Mugasha, W.A.","Nzunda, E.F."],"year":2019,"venue":"International Journal of Forestry Research","doi":"10.1155/2019/1876329","url":"https://doi.org/10.1155/2019/1876329","read_url":"https://onlinelibrary.wiley.com/doi/10.1155/2019/1876329","access":"open","checked_at":"2026-11-02","status":"current"},"name":"Miombo Regional BGB from stump diameter","output":{"quantity":"bgb"},"expression":"0.1056 * D30^2.1035","published":{"expression":"0.1056 * SD^2.1035","units":{"SD":"cm"},"variables":{"SD":"D30"},"output_unit":"kg"},"taxon":{"level":"mixed","name":"Miombo woodland trees (mixed species)","group":"broadleaf"},"region":{"scope":"regional","countries":["TZ"],"place":"Miombo woodlands of Manyara, Lindi and Tabora, Tanzania","biomes":["tropical"]},"stand":"natural","fit":{"n_trees":57,"r2":0.86,"method":"non-linear mixed-effects regression (nlme), power model"},"evidence":[{"field":"expression","quote":"Regional = a × (SD) b 0.1056 2.1035 623.5 154.01 46.5 -12.2 0.86","locator":"Table 6, selected model (1)"},{"field":"published.units","quote":"SD is stump diameter (cm)","locator":"Section 2.3.4"},{"field":"fit.n_trees","quote":"AGB and BGB models were developed from 127 and 57 sample trees, respectively","locator":"Abstract (volume: 114 trees)"}],"check":[{"inputs":{"D30":30},"expected":135.14,"origin":"computed","note":"hand-computed from the published form"},{"inputs":{"D30":60},"expected":580.77,"origin":"computed","note":"hand-computed from the published form"}],"verification":"original_read","checked_at":"2026-11-02","notes":"Stump diameter (SD) is measured over bark just below the felling cut, at least 30 cm above ground (higher when the stump is irregular), so it is mapped to D30 as the nearest canonical variable. Form Y = a × SD^b is the first (non-linear mixed-effects, nlme) model form; the paper selected it as best in every case shown here, and the printed Table row shows it. Manyara BGB is not included because the paper selected a different (quadratic) form there. The three model forms (1)-(3) are typeset equations; the form of (1) is read from the table row \"= a × (SD) b\". The fit used nlme with random effects; coefficients are the fixed effects as printed. Table 2 gives SD ranges, not DBH, so no dbh range is stored."}