{"id":"namm-2020-bgb-ba","source":{"id":"namm-2020","citation":"Namm, B. H., & Berrill, J.-P. (2020). How do tree- and stand-level factors influence belowground biomass and carbon storage in tanoak (Notholithocarpus densiflorus)? The Forestry Chronicle, 96(1), 50–60.","title":"How do tree- and stand-level factors influence belowground biomass and carbon storage in tanoak (Notholithocarpus densiflorus)?","authors":["Namm, B. H.","Berrill, J.-P."],"year":2020,"venue":"The Forestry Chronicle","doi":"10.5558/tfc2020-007","url":"https://doi.org/10.5558/tfc2020-007","read_url":"https://pubs.cif-ifc.org/doi/pdf/10.5558/tfc2020-007","access":"open","checked_at":"2026-11-02","status":"current"},"name":"Tanoak root biomass from basal area (best AICc model, Table 2)","output":{"quantity":"bgb"},"expression":"exp(6.683 + 0.8149 * ln(0.000078539816 * D^2))","published":{"expression":"exp(6.683 + 0.8149 * ln(0.000078539816 * DBH^2))","units":{"DBH":"cm"},"variables":{"DBH":"D"},"output_unit":"kg"},"taxon":{"level":"species","name":"Notholithocarpus densiflorus","family":"Fagaceae","group":"broadleaf"},"region":{"scope":"site","countries":["US"],"place":"L.W. Schatz Demonstration Tree Farm, Humboldt County, California","biomes":["temperate"]},"stand":"mixed","fit":{"n_trees":12,"dbh_min_cm":1.9,"dbh_max_cm":52.4,"h_min_m":2.7,"h_max_m":21.1,"r2":0.9425,"method":"linear mixed model on ln scale (block random effect), excavated root systems"},"evidence":[{"field":"expression","quote":"ln (Belowground biomass) = 6.683 + 0.8149( ln BA )","locator":"Table 2, last row (lowest AICc)"},{"field":"fit.n_trees","quote":"n = 12 trees","locator":"Table 2 caption"},{"field":"fit.dbh_min_cm","quote":"the dbh of individual stems were between 1.9 cm and 52.4 cm","locator":"Results, p. 53"},{"field":"fit.h_min_m","quote":"Tree heights ranged from 2.7 m to 21.1 m","locator":"Results, p. 53"},{"field":"fit.r2","quote":"0.9425","locator":"Table 2, R2 adj. of the best-AICc model"}],"check":[{"inputs":{"D":31.1},"expected":98,"origin":"published","note":"Results, p. 53: tanoak with average tree BA of 0.076 m2 (single-stemmed dbh 31.1 cm) expected to store 98 kg belowground (rounded in paper)"},{"inputs":{"D":15},"expected":29.7915,"origin":"computed","note":"computed from the published form (coefficients as printed)"},{"inputs":{"D":45},"expected":178.5273,"origin":"computed","note":"computed from the published form (coefficients as printed)"}],"verification":"original_read","checked_at":"2026-11-02","notes":"The paper's predictor is total stem basal area BA (m2, summed over all stems of a multi-stemmed tanoak). Here BA is written as pi/4 * (DBH/100)^2, so D is the dbh of a single stem; for multi-stemmed trees use the summed basal area instead. Output is belowground biomass excluding stump, in kg. r2 is the adjusted R2 as printed. The paper does not state a back-transformation correction factor, so none is applied. Other candidate models (with crown position, SDI, height) and the root:shoot models (arcsine transform, coefficients not legible in the text layer) were not added."}