Comparison of Log Quality from Even-Aged and Uneven-Aged Loblolly Pine Stands in South Arkansas

Log grade, number of knots, and log volume of the first two logs, as well as form class of the butt log, were compared across three broad sawtimber categories among even-aged plantations, even-aged natural stands, and uneven-aged natural stayMs of loblolly pine (Pinus taeda L.) in Ashley County, AR. Trees from unevenaged stands had butt logs of better log grade than even-aged plantations, particularly in the large sawtimber component where the average difference was half a log grade. Compared to even-aged natural stands, trees from uneven-aged stands had togs of comparable grade. Trees from evenaged natural stands produced butt logs of slightly better grade, but with greater taper and tess volume per log, than trees from even-aged plantations. To produce highgrade loblolly pine sawtimber in the West Gulf region, natural stand management will suffice; plantation management may require supplemental quality intervention such as artificial pruning. South. J. Appl. For. 15(1):10-17. The optimal si vicultural system to apply in a given situation depends in large part upon economic benefits that the system can • This study was conducted while the junior author was an undergraduate student in the Department of Forest Resources, University of Arkansas at Monticello, Monticello, AR. The authors acknowledge and thank the USDA Forest Service and the Mid-Continent Division, Georgia-Pacific Corp., for their generous assistance in the conduct of the study. This paper is approved for publication by the Arkansas Agricultural Experiment Station. provide for the landowner. Indicators such as growth and yield or economic assessments are easily quantified, are readily accessible to foresters and landowners, and provide a firm basis for silvicultural decision-making. However, stand characteristics that are less obvious, or for which there is no clearly defined price or value established through transaction, are often less firmly established as attributes of a particular system either in the silvicultural literature or through professional observation. Log quality considerations in pine sawtimber from even-aged and uneven-aged silvicultural systems fall in this category. Stumpage and mill-delivered prices for pine sawtimber are not explicitly subdivided by grade (Timber Mart-South 1986), although in weak markets high quality sawlogs will often be salable whereas low-quality sawlogs will not? Forest industries in south Arkansas that manage for sawtimber practice either evenaged or uneven-aged silviculture, and in some instances both, which indicates that sawlogs of acceptable minimum quality can be economically produced with either 2 Baker, J.B. 1985. Personal communication, Crossett Forestry Field Day, Crossett AR, May 1, 1985. approach. Specific observations about log quality and comparisons among different systems more closely resemble silvicultural lore than fact. The selection system has been reported to produce high quality southern pine timber (Reynolds 1969, Reynolds et al. 1984). In a study in south Arkansas, 41% of the logs harvested during the first 18 years of selection silviculture were grade 1 (according to Cros~ sett Lumber Co. log grading standards), but the proportion decreased to 35% during the subsequent 11 years (Reynolds 1959, 1969). This decline was attributed to a shift in origin of harvested trees from released virgin stock to second growth stock; the proportion of grade 1 logs was expected to increase with increasing duration of management of the second growth stand (Reynolds 1969). In addition, standard marking practice in selection silviculture in south Arkansas is to remove the worst trees and leave the best. Under ideal application, this approach removes trees of poor quality before they become large sawlogs, thereby promoting a stand-level increase in quality of large sawtimber. Plantations of southern pine are also reported to grow high quality trees. Higher stem quality was reported in plantations subject to early density control and thinning than was reported in stands in the absence of either treatment (Hughes and Kellison 1982). In reporting on the quality of trees removed from plantations during thinning, Sprinz et al. (1979) observed a greater number of high quality trees than nonquality trees. They also noted contradictory observations regarding stem density versus quality of trees removed; in one study, dense stands had more lower grade material removed from them than did less dense stands, but the converse was true in a second study. These authors did not state whether quality of residual trees was consistent with