{"id":"magalhaes-2015-root-system-d2h","source":{"id":"magalhaes-2015","citation":"Magalhães, T.M. (2015). Allometric equations for estimating belowground biomass of Androstachys johnsonii Prain. Carbon Balance and Management, 10, 16.","title":"Allometric equations for estimating belowground biomass of Androstachys johnsonii Prain","authors":["Magalhães, T.M."],"year":2015,"venue":"Carbon Balance and Management","doi":"10.1186/s13021-015-0027-4","url":"https://doi.org/10.1186/s13021-015-0027-4","read_url":"https://cbmjournal.biomedcentral.com/track/pdf/10.1186/s13021-015-0027-4","access":"open","license":"CC BY 4.0","checked_at":"2026-11-02","status":"current"},"name":"Root system dry biomass from DBH²·H (Table 4, form 6)","output":{"quantity":"bgb"},"expression":"0.007 * (D^2 * H)^1.0226","published":{"expression":"0.007 * (DBH^2 * TH)^1.0226","units":{"DBH":"cm","TH":"m"},"variables":{"DBH":"D","TH":"H"},"output_unit":"kg"},"taxon":{"level":"species","name":"Androstachys johnsonii","family":"Picrodendraceae","group":"broadleaf"},"region":{"scope":"regional","countries":["MZ"],"place":"Mabote, Funhalouro, Panda, Mandlakaze and Chibuto districts, Inhambane and Gaza provinces","biomes":["tropical","dryland"]},"stand":"natural","fit":{"n_trees":93,"dbh_min_cm":5,"dbh_max_cm":32,"h_min_m":5.69,"h_max_m":16,"r2":0.998,"method":"Weighted nonlinear least squares (nls, Gauss-Newton); r2 is the adjusted R² in Table 5; CVr = 23.1551%"},"evidence":[{"field":"expression","quote":"Root system 3 1/0.0003 × DBH3.8639 0.0070 (±0.0015)*** 1.0226 (±0.0251)***","locator":"Table 4, Root system rows, and Eq. (6; Ŷ = b0 × (DBH² × TH)^b1)"},{"field":"fit.n_trees","quote":"93 trees (DBH range 5–32 cm; TH range 5.69–16 m)","locator":"Methods, Data acquisition"},{"field":"fit.dbh_min_cm","quote":"DBH range 5–32 cm","locator":"Methods, Data acquisition"},{"field":"fit.r2","quote":"Root system 3 99.80 23.1551","locator":"Table 5, Root system"},{"field":"output","quote":"The dry weight of the root system was obtained by summing the dry weights of taproot and lateral roots (fine and coarse ones).","locator":"Methods, Data acquisition"}],"check":[{"inputs":{"D":8,"H":7},"expected":3.5999,"origin":"computed","note":"hand-computed from the Table 4 coefficients"},{"inputs":{"D":15,"H":10},"expected":18.752,"origin":"computed","note":"hand-computed from the Table 4 coefficients"},{"inputs":{"D":25,"H":13},"expected":69.708,"origin":"computed","note":"hand-computed from the Table 4 coefficients"}],"verification":"original_read","checked_at":"2026-11-02","notes":"Best independent root-system model by Adj.R² and CVr (\"model form 6, found to be the best\"). Weight function 1/(0.0003 × DBH^3.8639). The paper prints the DBH²·TH grouping as \"DBH 2 TH b1\" in the extracted text; the grouping is confirmed by b1 ≈ 1.02, as for a volume-like variable. Root system = taproot (including root collar) + lateral roots, excavated to full depth, fine roots included, dry mass at 105 C; stump above 20 cm is not part of it. Independent (not WNSUR additive) model, which the author recommends over the simultaneous ones. One of four independent root-system models in Table 4; all performed almost equally."}