Fertilization and thinning effects on plantation loblolly pine taper and wood qualityThis article is part of a larger document. View the larger document here.
Loblolly pine (Pinus taeda L.) plantation forestry continues to incorporate silvicultural advances that increase individual tree growth. These faster-growing trees may have different stem characteristics than their slower-growing predecessors, with unknown effects on wood quality. We examined fertilizer and thinning effects on individual tree taper and wood properties of loblolly pine in the Piedmont of Virginia, United States. Treatments included two levels of thinning (500 (unthinned) and 200 trees per acre residual density) and two levels of fertilization after thinning (none and 200 pounds of nitrogen + 25 pounds of phosphorus per acre) applied at age 15. Nine years after treatment application, age 24, trees (n = 24) were measured and destructively sampled. Wood disk samples were collected and evaluated for oven-dry specific gravity. Thinning significantly increased diameter at breast height (d.b.h.), with no significant change in total height. Log taper from 4.5 feet to 24 feet and wood specific gravity were not affected by treatment. Wood specific gravity at breast height ranged from 0.52 to 0.56. Overall, fertilizer and thinning increased the diameter of the first log without changing wood quality. Height to live crown significantly increased 9 feet at 500 trees per acre residual density compared to the 200 trees per acre, resulting in the potential for greater log length with live-branch-free mature wood growth, especially on the second log.