FS 254 Test 1 Formulas

General tips

• Diameter generally in cm

• Height in m

DBH graduation Biltmore stick

• A is fixed distance from eye, D is diameter.

Bark diameter models

• D_u.b. = a * D_o.b.

• D_u.b. = a + b * D_o.b.

Height from geometry

Height from shadow

Height from trigonometry

Height from diameter

Huber’s volume formula

Smalian’s volume formula

Newton’s volume formula

SA Forestry Handbook volume formula

SA Forestry Handbook V_u.b. for SW & HWs

Log stack estimation

• Logs of uniform length & tidy stack.

Form factors

• f = tree or stem volume / cylinder volume

• Absolute form factor (FF) - tree base diameter as reference

• True form factor (γ) - diameter at 10% tree’s height as reference

• Breast height or artificial or false form factor (f) - dbh as reference

• Field practice

Combined variable equation

Schumacher and Hall equation

• dbh in cm & height in m

• remember to e^{ln V}

Forestry Handbook taper estimation

Stems per hectare

• N is stems/ha, n is avg stems in plot, a is average plot size

• OR just Total Trees / Total Area

• 1ha = 100m * 100m = 10 000m²

Arithmetic mean d

Quadratic mean d

Conversion of quadratic and arithmetic mean diameter

Stand basal area from QMD

• B = k * N * (QMD)²

• k is basal area constant, N is stand density, QMD is quadratic mean diameter.

Stand volume approaches