Stand Structure and Yield Relationships in a 20-Year-Old Loblolly Pine Spacing Study

Abstract

A loblolly pine (Pinus taeda L.) spacing study on a Piedmont site (SI 75, base age 25) had at age 20 a maximum yield of 49 cords per acre with a near maximum basal area of 187 square feet at a spacing of 8 x 8 feet. Comparative yields on the other spacings tested were: 6 x 6, 188 ft² and 43 cords; 10 x 10, 166 ft² and 45 cords; 12 x 12, 152 ft² and 43 cords. Sawtimber volume in trees larger than 9.5 inches in diameter rose from zero at 6 x 6 feet to almost 10,000 board feet per acre at 12 x 12 feet. Survival on the 6 x 6 plots was 71 percent; 8 x 8, 87 percent; 10 by 10, 92 percent; and 12 x 12, 93 percent.