Woodland owner notes [2011 : March, no.13]

ijj Woodland rJ Owner Notes Thinning Pine Stands If done properly to ensure an adequate stand of remaining crop trees, thinning can improve pine stand use and increase the crop's final value. WHAT IS THINNING? Thinning is the cutting or removal of certain trees from a stand to regulate the number, quality, and distribution of the remaining crop trees. If the harvested trees can be marketed, the thinning is commercial. Where markets do not exist for the removed trees (usually because they are too small), the thinning is considered precom¬ mercial or noncommercial. WHY THIN? Number of trees per acre (called stand density or stocking ) affects yield and value growth of pine trees, just as site quality and age do. Like other crops, trees grow poorly if there are too many or too few per acre. Unlike most crops though, trees live long enough and grow large enough that the optimum number per acre changes. Deliberate control of stand density by thinning can improve the vigor, growth rate, and quality of the remain¬ ing “crop” trees. As a result, the forest landowner benefits in three ways: • Growth is concentrated on fewer, faster grow¬ ing trees. Faster growth reduces the time required to reach harvestable size, and larger trees bring higher prices. • Only high-quality trees are permitted to grow to final harvest, eliminating volume accumula¬ tion on low- value trees. • Trees which would stagnate or die before final harvest can be utilized. Intermediate harvests can provide periodic income, enhance wild¬ life values, improve forest health, and reduce wildfire risks. BIOLOGICALLY SPEAKING Pine trees need growing space in which they compete for water, nutrients, and light. With these inputs, the green needles in the crown manufac¬ ture food to increase the tree’s size. The larger tree can support an expanded crown which, in turn, can produce still more food. As a result, the fastest growing trees are the most successful competitors. They assume a “dominant” position in the stand where they continue to receive direct sunlight both from above and the sides. Since pines can¬ not tolerate shade, their branches thin out and die from the ground up, as the trees become crowded or overtopped. This leaves progressively smaller live green crowns, so the trees become less competitive and eventually die. Through this natural “thinning” process, a young natural stand having thousands of trees per acre or a plantation with 600 to 1,000 trees will be reduced to a few hundred trees per acre by approximately age 40. Since the forest undergoes a natural “thin¬ ning” process, what advantage is to be gained by thinning deliberately? Most sites produce about the same total wood volume with cither a lot of small trees or a few large ones. However, total wood volume is rarely a good indicator of market value. Individual trees determine the market product, and value increases with di¬ ameter. For example, the same volume of timber would approximately double in value if the trees were large enough to be used for chip’ n’ saw logs rather than pulpwood. That same volume in trees of sawtimber diameter would be about State University A&T State University COOPERATIVE EXTENSION Empowering People • Providing Solutions