VISUAL TREE GRADING SYSTEMS FOR ESTIMATING LUMBER YIELDS IN YOUNG ANDMATURE SOUTHERN PINE

New visual tree grading systems for mature southern pine greater than or equal to 35 years old and young pine < 35 years old based on number and size of branches in the lower bole are described. A series of lum ber grade yield studies was conducted to test the new grading rules. A total of 214 natural loblolly pine (Pinus taeda L.) and shortleaf pin e (P. echinata Mill) trees 9 to 20 inches diameter at breast height (D BH) were harvested from 37-, 39-, 42-, 56- and 73-year-old stands and 152 loblolly pine trees 9 to 18 inches DBH were harvested from 22-, 25 -, 27-, 34- and 39-year-old planted stands in the Georgia Piedmont. Th e study trees were graded using the new rules and processed into lumbe r. Results show the new grading rules separated trees into three signi ficantly different stumpage value classes based on lumber grade yield. Average stumpage value per hundred cubic feet (CCF) of sawlog was 16 percent higher for grade 1 trees compared to grade 2 trees, and that f or grade 2 trees was 27 percent higher than for grade 3 trees using th e rules for trees greater than or equal to 35 years old. Average stump age value per CCF of sawlog was 13 percent higher for grade 1 trees co mpared to grade 2 trees; that for grade 2 trees was 19 percent higher than for grade 3 trees using the rules for trees < 35 years old. Regre ssion equations are presented for estimating lumber grade yield based on tree grade, dimensions, and age. The grading systems were developed with the cooperative effort of state and federal agencies and industr y.(1)