{"id":"brown-iverson-1992-wet","source":{"id":"brown-iverson-1992","citation":"Brown, S., & Iverson, L. R. (1992). Biomass estimates for tropical forests. World Resources Review, 4, 366–384.","title":"Biomass estimates for tropical forests","authors":["Brown, S.","Iverson, L. R."],"year":1992,"venue":"World Resources Review","url":"https://www.fao.org/4/w4095e/w4095e0b.htm","access":"paywalled","checked_at":"2026-11-01","status":"current"},"name":"Wet tropical zone AGB, quadratic (Brown 1997 Eq. 3.2.5)","output":{"quantity":"agb"},"expression":"21.297 - 6.953 * D + 0.740 * D^2","published":{"expression":"21.297 - 6.953 * D + 0.740 * D^2","units":{"D":"cm"},"output_unit":"kg"},"taxon":{"level":"mixed","name":"Tropical broadleaf trees (mixed species)","group":"broadleaf"},"region":{"scope":"pantropical","countries":[],"place":"Tropics, wet zone","biomes":["tropical"]},"stand":"natural","fit":{"n_trees":169,"dbh_min_cm":4,"dbh_max_cm":112,"r2":0.92},"evidence":[{"field":"expression","quote":"Y = 21.297-6.953(D)+0.740(D2)","locator":"Eq. 3.2.5, Section 3.2.1 table"},{"field":"published.units","quote":"Y= biomass per tree in kg, D = dbh in cm, and BA = basal area in cm2","locator":"Section 3.2.1, biomass regression equations table header"},{"field":"notes","quote":"c From Brown and Iverson (1992)","locator":"Brown 1997, Section 3.2.1 table, footnote c"},{"field":"fit.n_trees","quote":"4-112 | 169 | 0.92","locator":"Brown 1997, Eq. 3.2.5 row: range in dbh (cm), number of trees, adjusted r2"}],"check":[{"inputs":{"D":30},"expected":478.71,"origin":"computed","note":"computed with python3 from the published form"}],"verification":"secondary","secondary_url":"https://www.fao.org/4/w4095e/w4095e06.htm","checked_at":"2026-11-01","notes":"Commonly cited as Brown (1997) Eq. 3.2.5, but the primer's footnote c attributes it to Brown and Iverson (1992), which could not be read; taken from Brown (1997). r2 is adjusted r². The primer does not say whether a log back-transform correction is included; none applied. Climatic zones per the primer: dry <1500 mm/yr rain with a dry season of several months; moist 1500–4000 mm/yr; wet >4000 mm/yr, lowland conditions only."}