Crown Lifting of Low-Density Loblolly Pine (Pinus taeda) Plantations on Nonindustrial Private Forest Lands


 Pruning or the physical removal of lower branches, in combination with wider tree spacing, offers an alternative management scheme for small nonindustrial private forest landowners in areas lacking markets for small diameter wood. A 5-year-old loblolly pine (Pinus taeda) plantation was thinned to 495 trees/ha (200 trees/ac). Four crown-lifting treatments of 35%, 40%, 45%, and 50% live crown ratio (LCR) were then implemented. An additional unmanaged plot was established in an unthinned, unpruned area. Two replications were established for all pruning treatments. The target LCR was maintained throughout the study with the additional crown-lifting activities in 2003, 2004, and 2008. At age 8, the average diameter of the unmanaged plot was 13.5 cm (5.3 in), and the diameter of the 50% LCR treatment, which had the greatest diameter growth of all the treatments, was 20.8 cm (8.2 in). The highest mortality rate (22%) was observed in the unmanaged plot, but it was not significantly greater than the other treatments. Low density plantings maintained with pruning could allow small nonindustrial private landowners to obtain a high value sawtimber product while eliminating the need for thinning practices commonly used in traditional pine plantation management.
 Study Implications: Pruning in combination with wider tree spacing offers an alternative management scheme for nonindustrial private forest landowners in areas lacking small diameter wood markets. This study compared the performance of thinned and pruned treatments with four live crown ratios (LCR) with unmanaged stands. At age 21, total tree height and survival were not affected by the treatments. The unmanaged plot had a significantly lower average diameter than all of the treatment plots. There was no significant difference in tree diameters between the pruned treatments. Therefore, the 50% LCR was most efficient since more pruning did not confer added growth gains.