{"id":"repola-2014-agb-birch","source":{"id":"repola-2014","citation":"Repola, J., Ahnlund Ulvcrona, K. (2014). Modelling biomass of young and dense Scots pine (Pinus sylvestris L.) dominated mixed forests in northern Sweden. Silva Fennica, 48(5), 1190.","title":"Modelling biomass of young and dense Scots pine (Pinus sylvestris L.) dominated mixed forests in northern Sweden","authors":["Repola, J.","Ahnlund Ulvcrona, K."],"year":2014,"venue":"Silva Fennica","doi":"10.14214/sf.1190","url":"https://doi.org/10.14214/sf.1190","read_url":"https://silvafennica.fi/pdf/1190","access":"open","checked_at":"2026-11-02","status":"current"},"name":"Birch aboveground biomass, young dense stands, N Sweden (Table 5)","output":{"quantity":"agb"},"expression":"exp(-4.074 + (0.002 + 0.018) / 2 + 7.970 * D / (D + 3) + (16.922) * H / (H + 10) + (-3.210) * ln(H))","published":{"expression":"exp(-4.074 + (0.002 + 0.018) / 2 + 7.970 * dbh / (dbh + 3) + (16.922) * h / (h + 10) + (-3.210) * ln(h))","units":{"dbh":"cm","h":"m"},"variables":{"dbh":"D","h":"H"},"output_unit":"kg"},"taxon":{"level":"genus","name":"Betula","family":"Betulaceae","group":"broadleaf"},"region":{"scope":"regional","countries":["SE"],"place":"Six young, dense, naturally regenerated stands in northern Sweden (63.26-65.69 N)","biomes":["boreal"]},"stand":"natural","fit":{"n_trees":86,"dbh_min_cm":1,"dbh_max_cm":11,"h_min_m":1.8,"h_max_m":8.6,"method":"linear mixed model of ln(biomass) with random stand effect; ln(y) = Intercept + b1 dbh/(dbh + n) + b2 h/(h + m) + b3 ln(h)"},"evidence":[{"field":"expression","quote":"Total above-ground, kg, birch: Intercept −4.074; dbh/(dbh + n) 7.970; h/(h + m) 16.922; ln(h) −3.210; n 3; m 10; var(uk) 0.002; var(eki) 0.018","locator":"Table 5, p. 12"},{"field":"expression","quote":"a variance correction term, ((var(uk) + var(eki))/2) should be added to the intercept to correct for bias due to the logarithmic transformation","locator":"Section 2.6, p. 10"},{"field":"fit.n_trees","quote":"In total, 280 trees were included in this destructive aboveground biomass study, of which 126 were pine, 68 spruce and 86 birch.","locator":"Section 2.4, p. 6"},{"field":"fit.dbh_max_cm","quote":"The range of dbh was 1–22 cm, 1–21 cm and 1–11 cm for pine, spruce and birch, respectively","locator":"Section 2.4, p. 6"},{"field":"fit.h_max_m","quote":"The range of heights was 1.7–11.7 m, 1.6–13.3 m and 1.8–8.6 m for pine, spruce and birch, respectively","locator":"Section 2.4, p. 6"}],"check":[{"inputs":{"D":5,"H":5},"expected":4.0214,"origin":"computed","note":"hand-computed from the Table 5 coefficients with the (var(u) + var(e))/2 intercept correction"},{"inputs":{"D":10,"H":8},"expected":18.4055,"origin":"computed","note":"hand-computed from the Table 5 coefficients with the (var(u) + var(e))/2 intercept correction"}],"verification":"original_read","checked_at":"2026-11-02","notes":"Fitted on pine-dominated mixed stands; fit n, DBH and height ranges are the species sample ranges. Expression applies the paper's stated additive correction (var(uk) + var(eki))/2 to the intercept. Variance values are as printed in Table 5; no other correction factor is stated. The paper models the total independently of the components, so it need not equal their sum. Birch coefficients are for Betula pendula and B. pubescens pooled. "}