(BA) 1. the cross-sectional area of a single stem, including the bark, measured at breast height (4.5 ft or 1.37 m above the ground) —note the international symbol for basal area is g 2. the cross-sectional area of all stems of a species or all stems in a stand measured at breast height and expressed per unit of land area 3. range management the cross sectional area of the stem or stems of a plant or of all plants in a stand —note herbaceous and small woody plants are measured at or near ground level, and larger woody plants are measured at breast or other designated height —synonym basal cover This definition last updated 10/24/2008