Pterocarpus angolensis / Stem volume

Merchantable stem volume from DBH and height (Model 6, Table 7)

Stem volumePterocarpus angolensis · FabaceaeNamibia, AngolanaturalRead from the original paper

Equation

As printed (Table 7, Model 6)

Vmer = exp(a + b 1 *(lnDBH)2 + b 2 *(lnDBH)3+ b 3 *lnH) ... -7.821 *** 0.599 *** -0.064 *** 0.800 ***

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

Stem volume = exp(-7.821 + 0.599 * ln(D)^2 - 0.064 * ln(D)^3 + 0.800 * ln(H))

D: Diameter at breast height (1.3 m), cm
H: Total tree height, m

Merchantable (saw wood) over-bark volume of the bole, excluding the stump; the bole is the stem up to the first branch, so mapped to stem_volume. Table 7 caption: intercept a includes the Baskerville correction factor, so nothing is added (no CF value printed). Quadratic and cubic terms of ln(DBH) as printed. Paper's RSE is on the volume scale (m3), so fit.rse is left out; R2 is the printed adjusted R2.

Source

De Cauwer, V., Beeckman, H., Kleinn, C., Moses, M., Nott, A., Seifert, T., Muys, B. (2020). Improving the knowledge base for tropical dry forest management in southern Africa: Regional volume models for Pterocarpus angolensis. Forest Ecology and Management, 477, 118485.

doi:10.1016/j.foreco.2020.118485 · Open access · copy we read

Data of 340 trees were used for Model 6 and 356 trees for all other models. DBH range is between 5 and 92 cm.

Trees measured · Table 7 caption

Trees measured: 340
DBH range: 5–92 cm
R²: 0.95
Method: Regression on ln scale with Baskerville correction in intercept; adjusted R2
Where: Baikiaea-Pterocarpus woodlands of northern Namibia and southern Angola (MAP 480-700 mm)
Last checked: 2026-11-02

Calculate

DBH (cm)Height (m)

Height from

0.0819

Stem volume (m³)

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%.

Inputs	Expected	We get	From
D = 20, H = 8	0.0819	0.0819	Computed from the printed form hand-computed from the published form
D = 50, H = 14	0.688	0.688	Computed from the printed form hand-computed from the published form

Report a problem with this equation · JSON

Merchantable stem volume from DBH (Model 4, Table 7) · De Cauwer et al. 2020 · DBH
Merchantable stem volume from DBH (Model 4, Table 7) · same paper · Stem volume
Total wood volume from DBH and height (Model 3, Table 5) · same paper · Total volume
Total wood volume from DBH (Model 1, Table 5) · same paper · Total volume

Compare these curves

Merchantable stem volume from DBH and height (Model 6, Table 7)

Related