Pruning pines enhances growth , market value James Ronald Skains Dr. Terry Clason, now with the National Resource Conservation Service (NRCS) of the USDA in Alexandria but formerly at the LSU Hill Farm Research Station at Homer has been a leading researcher for many years on the benefits of pruning and proper thinning of pine plantation stands. "While I was at the Hill Farm Station, we did extensive research on the benefits of pruning in both early and late rotations," Dr. Clason told the Piney Woods Journal. "We published several studies of our research work." Dr. Clason directed the Journal to one published article that included some of his work. It was published in August 2006 by the USDA National Agroforestry Center. In this article, Dr. Clason writes: "Four factors determine when silvopasture trees should be pruned: trunk diameter, branch diameter, tree height and season of the year." "The object of pruning is to confine the knots created by the pruned branches to a small diameter (four inches) of core wood thereby producing high quality, knot-free wood on the outer portion of the tree trunk." Dr. Clason also pointed out, "Try to remove branches before they exceed two inches in diameter. Maintain a live crown of no less than one-third of the tree height, and prune in the dormant season or very early spring before active growth begins." Harry Meadows of Troy, Alabama who worked with the Southern Pine Inspection Bureau (SPIB) for many years told the Journal, "The problem with fast growth southern yellow pine is that you don't get much real grade lumber from it because of the knots." "The longer the tree grows before its bottom limbs are pruned naturally by dying and falling off, the lower the grade lumber you will get out of the tree," Meadows added. "The longer the lower limbs grows on a tree, the more years it takes for the tree to over-grow the knot. The more knots that you have closer to the outer surface of the tree, the lower the grade of lumber you get out of the tree," Meadows pointed out. "The key to the best grade of lumber is either old growth timber or plantation pine that has been pruned at an early age to give the tree more years to over grow or bury the knot deeper in the tree." "A few of the timber companies here in south Alabama including Slawson Wood Manufacturing has been manually pruning trees for a number or years with significant favorable results," Meadows noted. "Two positives can result when plantation pine is pruned early and then thinned at the proper time. First, you can grow a better grade of lumber faster; and secondly, pruning and thinning together gives you good chance of growing high dollar poles," Meadows concluded. Tim Traugott, Area Extension Forester with Mississippi State University in MSU publication #2260 described the process of natural pruning: "Since pines do not tolerate shade, their branches die from the ground up as trees become crowded and over-topped. These dead limbs, over time, will shed or fall off the trees. This is known as 'natural pruning' and results in a tree of higher value with a clean stem and a well-developed crown." Traugott also pointed out in his report: "Tree growth needs to concentrated on the main pole of the tree, supported by a well-developed crown. Thinning too early can result in growing larger lower limbs, which eventually lower the quality of the logs, inhibit diameter growth, and reduce the value of the tree." An approximate table for rough determination of number of trees per cord (128 cubic feet) by Traugott revealed that: it takes 46 trees with a 5-inch diameter at breast height (dbh) to equal one cord of wood. However, it only takes 21 trees with a dbh of 6 inches to equal a cord and 10 trees with an 8 inch dbh to make a cord. "There is another angle to pruning pine plantations," Travis Taylor, longtime Piney Woods logger told the Journal. "Pruning pines at an early age which allows the knot to over grow also produces a better grade of veneer for plywood. A plywood mill can take younger timber that has been pruned and cut veneer for plywood sheathing that doesn't have knots," said Taylor, the Vice President of the American Logging Council. "The less knots you have in the veneer in the plywood, the more valuable the plywood. There are a couple of companies here in the mid-south that started pruning a number of years ago with this in mind, both grade lumber and premium grade plywood," Taylor pointed out. "The results for their plywood mills have been very good. These companies have built a excellent reputation for their plywood in the building material industry." A few years ago, the Piney Woods Journal did a couple of articles about Almond Brothers Lumber in Coushatta, Louisiana. It was noted in those articles that Almond Brothers exported 95% of their southern pine lumber to Europe to be used in moldings, doors, and exposed beams. It was also pointed out in these articles about the Almond Brothers operation that they only used the first or butt cut of a tree to make their premium grade lumber to be exported. This first cut or butt cut was old growth timber that had pruned itself and over the years had grown layers over the knots. In the November 2005 issue of the Southern Journal of Applied Forestry, researchers Holley, A. Gordon, Tate F. Jayson, and Eric Taylor published their research findings. The online abstract of their study reads as follows: A time and motion study was conducted to determine time and cost of pruning thinned, 12 year-old loblolly pine plantations to a height of 25 ft. The study incorporated thinning treatments to stand density indices of 70, 120, and 170. Pruning times with labor and equipment cost were used to determine per acre and per tree pruning costs at each stand density. Pruning costs were used to determine stumpage price premiums necessary to break-even on a pruning investment. Calculations were performed with various hourly wage and interest rates. The average per tree pruning time for a pair of workers was 2 minutes and 16 seconds, which results in a net average of 11.6 trees pruned per hour per worker. Per acre combined labor and equipment costs ranged from $58.09 to $288.59 depending on stand density and wage paid. Cost per tree ranged from $0.55 to $1.00 depending on stand density and wage paid. Break-even values ranged upwards from $63.55 to $2,584.14 per acre depending on stand density, wage paid, alternative rate of return, and rotation age. TimberLine magazine ran an article in its February 2009 issue about Osyka, Mississippi logger Robert Wall who has been pruning for a number of years using a dangle head piece of equipment (2,800 pounds) similar to a delimber mounted on an excavator. Wall was quoted as saying: "Pruning can be done 10 months of the year. We only have two months when we can't prune because of the sap rising. Pruning makes a significant difference to grade lumber yield," Wall added in the TimberLine article. "Now, a sawmill operator can go down to six inches before hitting knots. Previously, with un pruned plantation trees it was ten inches so they are getting four inches more lumber without knots." John C. Adams, PhD with a emphasis on Forest Genetics and Silviculture weighed in with the Journal on the subject of pruning plantation pine, "The advantage of pruning is clear wood which is more valuable and is easily captured by timber organizations who have their own sawmills." Dr. Adams, the former head of the Louisiana Tech University School of Forestry also noted "There are a couple of factors to take into consideration on pruning for private land owners. First, the private landowner must be able to substantiate to timber buyers that the bole of the tree is free of knots. Secondly, pruning must come early in the rotation and any changes in the ownership could muddy the picture unless verification of pruning can be carried over in an ownership change," Dr. Adams explained. "If there is a technique developed to obtain value as fuel-wood for the materials pruned, then the pruning technique becomes more valuable for the small landowner." |