S2The Forest Service hardwood tree grades for factory lumber are described, and lumber grade yields for 111 species are presented. The yields, expressed in board feet, are based on equations in which dbh2 and merchantable height were used as independent variables. Actual board-foot volumes by lumber grade served as dependent variables. Species included are yellow and paper birch, red and sugar maple, yellow-poplar, black cherry, basswood, and northern red, black, white, and chestnut oak. S3`