{"id":"lambert-2005-sugar-maple-dbh-h","source":{"id":"lambert-2005","citation":"Lambert, M.-C., Ung, C.-H., Raulier, F. (2005). Canadian national tree aboveground biomass equations. Canadian Journal of Forest Research, 35(8), 1996–2018.","title":"Canadian national tree aboveground biomass equations","authors":["Lambert, M.-C.","Ung, C.-H.","Raulier, F."],"year":2005,"venue":"Canadian Journal of Forest Research","doi":"10.1139/x05-112","url":"https://doi.org/10.1139/x05-112","read_url":"https://www.esf.edu/quest/documents/Lambertetal.2005.Canadatreebiomass.pdf","access":"paywalled","checked_at":"2026-11-03","status":"current","notes":"All 33 species are entered, each with total aboveground, stem (wood + bark), branch and foliage equations, for both the dbh-only set (Table 3) and the dbh + height set (Table 4). The paper's hardwood, softwood and all-species equations are not entered: they are meant for species outside the 33, and this library shows pooled fits only on the pages of species they name. Ung, Bernier & Guo (2008, CJFR 38:1123–1132, doi:10.1139/X07-224) re-estimated parameters for six species after adding British Columbia data and added eight BC species; no legal open copy of that paper was found (NRCan's repository lists it without a file), so Lambert 2005 parameters are used here."},"name":"Canadian national equation, sugar maple, dbh and height (sum of wood, bark, branches, foliage; Table 4)","output":{"quantity":"agb"},"expression":"0.0301 * D^2.0313 * H^0.8171 + 0.0103 * D^1.7111 * H^0.8509 + 0.0661 * D^2.594 * H^(-0.4933) + 2.5019 * D^2.4527 * H^(-2.3008)","published":{"expression":"0.0301 * dbh^2.0313 * H^0.8171 + 0.0103 * dbh^1.7111 * H^0.8509 + 0.0661 * dbh^2.594 * H^(-0.4933) + 2.5019 * dbh^2.4527 * H^(-2.3008)","units":{"dbh":"cm","H":"m"},"variables":{"dbh":"D"},"output_unit":"kg"},"taxon":{"level":"species","name":"Acer saccharum","family":"Sapindaceae","group":"broadleaf"},"region":{"scope":"regional","countries":["CA"],"place":"Ontario and Quebec, Canada (ENFOR archival data, early 1980s)","biomes":["temperate"]},"fit":{"n_trees":235,"dbh_min_cm":2,"dbh_max_cm":57.8,"h_min_m":2.6,"h_max_m":26.4,"r2":0.97,"method":"Nonlinear seemingly unrelated regression with weight functions; additivity constrained so compartments sum to total"},"evidence":[{"field":"expression","quote":"y wood = β wood1D βwood2Hβwood3 + ewood","locator":"Eq. 3"},{"field":"expression","quote":"y bark = β bark1D βbark2Hβbark3 + e bark","locator":"Eq. 3"},{"field":"expression","quote":"y branches = β branches1D βbranches2Hβbranches3 + e branches","locator":"Eq. 3"},{"field":"expression","quote":"y foliage = β foliage1D βfoliage2Hβfoliage3 + efoliage","locator":"Eq. 3"},{"field":"expression","quote":"Sugar maple bwood1 0.0301","locator":"Table 4, Sugar maple"},{"field":"expression","quote":"bwood2 2.0313","locator":"Table 4, Sugar maple"},{"field":"expression","quote":"bwood3 0.8171","locator":"Table 4, Sugar maple"},{"field":"expression","quote":"bbark1 0.0103","locator":"Table 4, Sugar maple"},{"field":"expression","quote":"bbark2 1.7111","locator":"Table 4, Sugar maple"},{"field":"expression","quote":"bbark3 0.8509","locator":"Table 4, Sugar maple"},{"field":"expression","quote":"bbranches1 0.0661","locator":"Table 4, Sugar maple"},{"field":"expression","quote":"bbranches2 2.5940","locator":"Table 4, Sugar maple"},{"field":"expression","quote":"bbranches3 –0.4933","locator":"Table 4, Sugar maple"},{"field":"expression","quote":"bfoliage1 2.5019","locator":"Table 4, Sugar maple"},{"field":"expression","quote":"bfoliage2 2.4527","locator":"Table 4, Sugar maple"},{"field":"expression","quote":"bfoliage3 –2.3008","locator":"Table 4, Sugar maple"},{"field":"fit.n_trees","quote":"Sugar maple            235     24.6±0.9     17.3±0.3     466.9±30.7","locator":"Table 2 (No. of trees)"},{"field":"fit.dbh_min_cm","quote":"(2.0;57.8)   (2.6;26.4)    (1.6;2421.1)","locator":"Table 2, Sugar maple (ranges of dbh, height, total biomass)"},{"field":"fit.r2","quote":"Total 0.0828 0.97 87.6 3.28 0.1126 0.97 78.8 3.09","locator":"Table 5, Sugar maple (AdjRSq in the dbh- and height-based set, second block)"}],"check":[{"inputs":{"D":20,"H":15},"expected":187.0882,"origin":"computed","note":"computed from the published form at dbh = 20 cm, H = 15 m"}],"verification":"original_read","checked_at":"2026-11-03","notes":"Total aboveground biomass = wood + bark + branches + foliage, each fitted as its own equation; the total is their sum (additivity by construction). r2 is the adjusted R² (AdjRSq) of this compartment in Table 5. Fitted on the original scale (weighted nonlinear seemingly unrelated regression), so there is no back-transform correction. Dead branches, cones and fruits are not part of aboveground biomass in this work (Materials). Stand type was not always recorded. Ung, Bernier & Guo (2008) later revised parameters for some species with British Columbia data; not used here."}