Tree Allometrics

Equations / Stem volume

Commercial stem volume from DBH, Couratari (species-specific, Table 2)

Stem volumeCouratari · LecythidaceaeBrazilnaturalRead from the original paper
Covers the whole genus
Equation

As printed (Table 2, SSEs rows)

Couratari sp. vc = exp(-5.53516 + 1.71104ln(DBH)) 0.48 2.635 31.0

In this library's units, ready to compute (m³)

Stem volume = exp(-5.53516 + 1.71104 * ln(D))
D
Diameter at breast height (1.3 m), cm

Species-specific equation (Couratari sp., Tauarí). vc is the commercial volume of the stem (sum of Smalian log volumes, hollows discounted), not total tree volume. No back-transformation correction factor is stated, so none is applied. n_trees is the adjustment (fitting) set; DBH range is that of the whole dataset (all species), not stated per species. Ten percent of trees were held out for validation. 8 of the 36+1 species equations in Table 2 were added (the ten most important commercial species by harvested volume plus H. petraeum); the generic FMA equation was rejected by the authors' own paired t-test. Couratari sp. in the paper (species not identified); genus-level taxon.

Source
Couratari sp. Tauarí 2,974 330
Trees measured · Table 1 (columns: adjustment, validation)
29,119 trees (50.0 cm ≤ DBH ≤ 175.0 cm) of 43 commercial species
Smallest DBH · Material and Methods, Data collection
composed the commercial volume (vc) of the stem
Output · Material and Methods, Data collection
Trees measured
2,974
DBH range
from 50 cm
R²
0.48
Method
Model 2 (Husch) fitted by least squares on ln(vc); r2 is the adjusted R² recalculated in arithmetic units; Syx = 2.635 m3 (31.0%)
Where
Tapajós National Forest, Pará (community forest management concession), eastern Brazilian Amazon
Last checked
2026-11-02
Calculate
4.35
Stem volume (m³)
Fitted DBH range024681012141620406080100120DBH (cm)Stem volume (m³)Stem volume

Shaded: the DBH range the model was fitted on. Other inputs held at the values above.

Checks this equation passes

On every build, the library's form and the paper's own form (in its units) must both give these values within 1%.

InputsExpectedWe getFrom
D = 604.354.35Computed from the printed form
hand-computed from the Table 2 coefficients
D = 908.718.71Computed from the printed form
hand-computed from the Table 2 coefficients
D = 13016.316.3Computed from the printed form
hand-computed from the Table 2 coefficients

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