Basal Area per Acre (Prism Cruise)
Stand basal area per acre from a variable-radius (prism / angle-gauge) point sample.
Example
You enter
- Basal-area factor (BAF, ft²/ac) 10
- Trees counted 'in' 8
- Tree DBH (in, for the expansion) 14
You get
- Basal area per acre 80 ft^2/ac
- Per-tree basal area 1.069 ft^2
- Trees per acre (one in-tree) 9.4 trees/ac
Checked against published worked examples from: USDA Forest Service mensuration / Bitterlich variable-radius plots.
Details, formula, and sources
ScopeBAF x the count of trees 'in', plus the per-tree basal area (0.005454 x DBH^2) and the trees-per-acre one in-tree represents. The prism counts by angular size, not distance -- the basal area per acre is independent of any plot radius.
Formula or tablebasal_area_per_acre = BAF x in_tree_count; per_tree_ba = 0.005454 x DBH^2; trees_per_acre = BAF / per_tree_ba.
Source and editionPrism (variable-radius / angle-gauge) point sampling, per USDA Forest Service mensuration and Bitterlich variable-radius plots, by name.
Free accessPoint-sampling relations are public forest-mensuration results; the 0.005454 constant converts DBH inches to basal-area square feet.
What governsEstimate. AHJ and licensed professional govern.
API field namesbaf, in_tree_count, dbh_in, basal_area_per_acre, per_tree_ba, trees_per_acre
- Angular sampling the prism selects trees by angular size, not distance; the per-acre basal area is BAF x count, independent of plot radiusBitterlich variable-radius plots
- Per-tree constant per-tree basal area = 0.005454 x DBH^2 (DBH in inches, area in ft^2)forest mensuration