The longest active thinned and pruned loblolly pine permanent plots: the last measurementThis article is part of a larger document. View the larger document here.
The longest active study of the effects of thinning and pruning on growth of loblolly pine (Pinus taeda L.) was established by Dr. James D. Burton in 1970 in a typical 12-year-old loblolly pine (plantation was 11 years old) stand planted by then the Georgia-Pacific Corporation in the southeastern corner of Arkansas. Basal area has been maintained at 30, 50, 70, and 90 square feet per acre by periodic thinnings. Within each level of basal area plots were pruned in two stages at 12 and 15 years, finally clearing the bole to heights of 33, 26, and 22 feet and reducing crown lengths to 25, 40, and 50 percent of the total tree height, respectively. Five control plots (without thinning or pruning) were installed at age 27. The 50-year remeasurement in the fall of 2007 will be the last since the study will be clearcut. Observed stand dynamics by thinning and pruning levels show that unthinned plots produced the maximum standing volume while moderate pruning did not substantially affect volume.