{"id":"koala-2017-bgb-ba13-all-species","source":{"id":"koala-2017","citation":"Koala, J., Sawadogo, L., Savadogo, P., Aynekulu, E., Heiskanen, J., Saïd, M. (2017). Allometric equations for below-ground biomass of four key woody species in West African savanna-woodlands. Silva Fennica, 51(3), article 1631.","title":"Allometric equations for below-ground biomass of four key woody species in West African savanna-woodlands","authors":["Koala, J.","Sawadogo, L.","Savadogo, P."],"year":2017,"venue":"Silva Fennica","doi":"10.14214/sf.1631","url":"https://doi.org/10.14214/sf.1631","read_url":"https://silvafennica.fi/pdf/1631","access":"open","license":"CC BY-SA 4.0","checked_at":"2026-11-01","status":"current"},"name":"Root biomass from basal area at breast height, all four species","output":{"quantity":"bgb"},"expression":"1084.9 * (0.7853982 * (D/100)^2)^0.88","published":{"expression":"1084.9 * (0.7853982 * (DBH/100)^2)^0.88","units":{"DBH":"cm"},"variables":{"DBH":"D"},"output_unit":"kg"},"taxon":{"level":"mixed","name":"Four Sudanian savanna-woodland species (Anogeissus leiocarpa, Detarium microcarpum, Piliostigma thonningii, Vitellaria paradoxa)","group":"broadleaf","members":["Anogeissus leiocarpa","Detarium microcarpum","Piliostigma thonningii","Vitellaria paradoxa"],"members_complete":true},"region":{"scope":"regional","countries":["BF"],"place":"Tiogo and Laba state forests, Burkina Faso (north Sudanian savanna-woodland)","biomes":["tropical","dryland"]},"stand":"natural","fit":{"n_trees":100,"dbh_min_cm":1.59,"dbh_max_cm":23.87,"r2":0.56,"method":"nonlinear regression, BGB = a × BA1.3^b"},"evidence":[{"field":"expression","quote":"BA1.3 1084.9 603.0 0.88 0.09 0.56 0.85 <0.0001","locator":"Table 2, BA1.3 row, All species, p. 7"},{"field":"expression","quote":"BGB = a × BA1.3b + ε","locator":"Eq. 4, p. 5"},{"field":"published.units","quote":"basal area (m2) at 1.3 m above ground level (BA1.3)","locator":"Table 2 caption, p. 7"},{"field":"fit.n_trees","quote":"All species 100 31.9±1.6 8 86 21.6±1.4 5 75","locator":"Table 1, p. 4 (N, then C0.2, C1.3 columns)"}],"check":[{"inputs":{"D":10},"expected":15.24,"origin":"computed","note":"computed from the published form with BA1.3 = pi*D^2/4 in m2"}],"verification":"original_read","checked_at":"2026-11-01","notes":"Not one of the authors' best models (they recommend basal area at 0.2 m, BA0.2, which has no canonical diameter variable here, and BA×H terms); this is the breast-height-only fit from Table 2, included because it can be used with DBH. Paper input is basal area at 1.3 m in m2; here BA1.3 is computed from DBH as pi*D^2/4 (0.7853982*(D/100)^2) in both forms. Fit dbh range is the printed C1.3 min and max divided by pi (circumference at 1.3 m, Table 1). BGB is stump plus coarse roots (roots over 5 mm for the non-protected species) from excavation, oven-dry. Table 2 prints a and b to 1 or 2 decimals. No correction factor is stated. Only the BA1.3-only models are included: the paper's height columns are labelled cm while the coefficients only make sense with H in metres, so the BA×H and H models are left out. Generic model fitted across the four species. For forked trees the paper's C1.3 is the quadratic sum of stem circumferences (Eq. 1, p. 4), so D here is the equivalent diameter sqrt(ΣDi²)."}