Definition: The cross section area of the stem or stems of a plant or of all plants in a stand, generally expressed as square units per unit area. Tree basal area is used to determine percent stocking. For shrubs and herbs it is used to determine phytomass. Grasses, forbs, and shrubs usually measured at or less then 1 inch above soil level.
For trees: the cross section area of a tree stem in square feet commonly measured at breast height (4.5' above ground) and inclusive of bark, usually computed by using d.b.h. or tallied through the use of basal area factor angle gauge.
The basal area factor is the number of units of basal area per acre (or per hectare) represented by each tree. The formula for basal area = (3.1416 x DBH2)/(4 x 144). This formula simplifies to: basal area = 0.005454 x DBH2
0.005454 is called the "foresters constant", which converts inches into square feet.
The basal area of a 10-inch tree is: 0.005454 x (10)2 = 0.5454 square feet (ft2). So, 100 of these trees per acre would calculate out a BA of 54 ft2.
Pronunciation: baze-ul area (noun)
Common Misspellings: basel area - basil area