{"id":"lambert-2005-yellow-birch-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, yellow birch, dbh and height (sum of wood, bark, branches, foliage; Table 4)","output":{"quantity":"agb"},"expression":"0.0259 * D^1.9044 * H^0.9715 + 0.0069 * D^2.0834 * H^0.5371 + 0.0325 * D^2.3851 + 0.1683 * D^1.2764","published":{"expression":"0.0259 * dbh^1.9044 * H^0.9715 + 0.0069 * dbh^2.0834 * H^0.5371 + 0.0325 * dbh^2.3851 + 0.1683 * dbh^1.2764","units":{"dbh":"cm","H":"m"},"variables":{"dbh":"D"},"output_unit":"kg"},"taxon":{"level":"species","name":"Betula alleghaniensis","family":"Betulaceae","group":"broadleaf"},"region":{"scope":"national","countries":["CA"],"place":"Canada: Newfoundland and Labrador, Ontario, Quebec (ENFOR archival data, early 1980s)","biomes":["boreal","temperate"]},"fit":{"n_trees":280,"dbh_min_cm":0.8,"dbh_max_cm":70.3,"h_min_m":2.7,"h_max_m":25.6,"r2":0.94,"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":"Yellow birch bwood1 0.0259","locator":"Table 4, Yellow birch"},{"field":"expression","quote":"bwood2 1.9044","locator":"Table 4, Yellow birch"},{"field":"expression","quote":"bwood3 0.9715","locator":"Table 4, Yellow birch"},{"field":"expression","quote":"bbark1 0.0069","locator":"Table 4, Yellow birch"},{"field":"expression","quote":"bbark2 2.0834","locator":"Table 4, Yellow birch"},{"field":"expression","quote":"bbark3 0.5371","locator":"Table 4, Yellow birch"},{"field":"expression","quote":"bbranches1 0.0325","locator":"Table 4, Yellow birch"},{"field":"expression","quote":"bbranches2 2.3851","locator":"Table 4, Yellow birch"},{"field":"expression","quote":"bbranches3 —","locator":"Table 4, Yellow birch"},{"field":"expression","quote":"bfoliage1 0.1683","locator":"Table 4, Yellow birch"},{"field":"expression","quote":"bfoliage2 1.2764","locator":"Table 4, Yellow birch"},{"field":"expression","quote":"bfoliage3 —","locator":"Table 4, Yellow birch"},{"field":"fit.n_trees","quote":"Yellow birch           280     25.7±0.9     16.4±0.3     494.4±34.4","locator":"Table 2 (No. of trees)"},{"field":"fit.dbh_min_cm","quote":"(0.8;70.3)   (2.7;25.6)    (0.1;2951.4)","locator":"Table 2, Yellow birch (ranges of dbh, height, total biomass)"},{"field":"fit.r2","quote":"Total 2.8971 0.94 145.5 2.34 0.9527 0.94 135.6 2.59","locator":"Table 5, Yellow birch (AdjRSq in the dbh- and height-based set, second block)"}],"check":[{"inputs":{"D":20,"H":15},"expected":172.1171,"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). Height drops out of the branches, foliage term: the paper leaves its height exponent blank (—, not significantly different from zero). 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."}