EFFECT OF INITIAL SPACING AND THINNING ON LUMBER GRADE, YIELD, AND STRENGTH OF LOBLOLLY-PINE

The effect of initial spacing and thinning on grade, strength, and vol ume of lumber produced from loblolly pine (Pinus taeda L.) in southwes t Louisiana was examined. Plots planted at spacings of 6 by 6, 8 by 8, 9 by 9, 10 by 10, and 12 by 12 feet were thinned to residual basal ar eas of 60, 80, 100, and 120 ft.2/acre at age 18 and at 5-year interval s through age 38. Trees thinned from the plots at age 38 were processe d into lumber. Based on study tree data, equations were developed to p redict total lumber volume and volume of No. 2 and better lumber produ ced from individual trees. A simulated final harvest at age 38 showed plots planted at 6 by 6 feet and thinned to less-than-or-equal-to 100 ft.2/acre produced greater-than-or-equal-to 60 percent No. 2 and bette r lumber compared to less-than-or-equal-to 42 percent No. 2 and better lumber from plots planted 12 by 12 feet and thinned to the same basal area.