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Wayne Clatterbuck, professor of forest management at the University of Tennessee, shares some hardwood management tips with us this week:
Careful management of young hardwood stands (even-aged, 15-to-30 years old) can greatly increase the future value of trees for sale as sawlogs. One goal of managing young hardwood stands is to produce trees that have long, straight stems without branches for the lower 16-to-35 feet of their length at maturity and are free of defects. The process of increasing the value of the stand involves three steps: selecting crop trees, releasing the stand, and harvesting sawlogs.
? Selecting crop trees: Sawlog crop trees are those grown as an investment in the future. Select trees of the more highly-valued species, whether for timber or wildlife value, with straight boles and few branches. Species should be selected that are well-adapted to the site and stand conditions. Trees in the intermediate or suppressed (overtopped) crown classes are not good candidates for crop trees.
In Tennessee, examples of species that are often selected as crop trees are oaks, yellow-poplar, walnut, cherry (higher elevations), hard maple and hickories. Usually 40 to 60 desirable and well-distributed crop trees per acre are selected in well-stocked stands before the initial release treatment.
? Releasing the stand: Thinning a stand to give crop trees more room to grow is accomplished by removing trees that would compete with crop trees for sunlight, water and nutrients. Through natural competition, vigorous trees suppress slower growing trees causing them to succumb before they are large enough to be harvested. Thinning allows the faster-growing, larger, and more valuable trees to grow to a commercial size in less time.
Thinning also promotes the overall health of the stand by removing defective, poorly-formed or diseased trees. Hardwood stands are usually thinned and trees released in an initial thinning and again every 10-to-20 years until trees reach marketable size.
Care should be taken not to thin too many trees at one time. Some competition with other trees is desired to encourage the growth of tall, straight, unforked stems, and to inhibit the growth of lower branches. If too many trees are removed, new branches may sprout along the stems of the remaining trees, causing defects and reducing wood value. Trees removed during thinning can be used for fuel wood, poles, and pulpwood if those markets are available.
? Harvesting sawlogs: Once your trees reach a commercial size, they can be sold as sawlogs. The length of time it takes to reach a marketable size depends on the species of trees, site productivity and the market. Trees, when they reach maturity continue to increase in volume, but at a decreasing rate.
Depending on the value of the stand (usually based on species value), this diminishing growth rate typically indicates that the stand should be cut (diminishing returns).
Consult with your local forester or county UT Extension office for assistance with selecting, releasing (thinning) and harvesting your crop trees.