- Introduction
Lesson- Practice
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Lesson
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What is timber stand improvement? Timber stand improvement is an attempt by a landowner, normally under the guidance of a forester, to create the best possible forest for the landowner’s objectives. Some objectives a landowner may have are:
Some landowners may even have the primary objective of creating a recreation area for camping, bird watching, hiking, etc. A forester must be able to determine what tree species and management techniques would help the landowner to meet their objectives. In order to help a landowner meet their objectives, a forester must make a decision about what to do with each tree. The forester has three choices:
Harvest is when a tree is sawed down, and taken to a mill to be sold. Leave is simply where the forester leaves a tree as it is. It is not altered in anyway. Deaden is when a forester believes it is necessary to kill a tree. This is normally only done when the tree is too small to be harvested. Typically a tree is killed by mechanical means, such as cutting it down or running it over with a skidder. It may also be accomplished by chemical means using herbicides. Another way is girdlingGirdling is when a forester removes about 1” of bark from all the way around the tree. This cuts the cambium layer which houses the xylem and phloem that are responsible for water and nutrient transportation from the roots to the leaves.. For a forester to make the best decision, he or she must also understand the different size classes of trees. There are four different size classes:
Dominant trees are trees that extend above surrounding individuals and capture sunlight from above and around the crown. A co-dominant is a tree that extends its crown into the canopy and receives direct sunlight from above, but limited sunlight from the sides. An intermediate tree is a tree that trees with crowns that extend into the canopy with dominant and co-dominate trees. These trees receive little direct sunlight from above and none from the sides. Crowns generally are small and crowded on all sides. Suppressed trees are characterized by low growth rate and low vigor as a result of competition with overtopping trees. Now that a forester understands the landowners objectives, and the different size classes, how does he decide which trees should harvested, left, and deadened? Harvest: When a forester makes the decision to harvest, it should first be based on if that tree is interfering with another tree. Landowners want to leave their genetically best tree to produce seedlings for the next generation of the forest. However, if there is not a great tree in a specific area, it is better to leave an average tree, than have a hole in the forest and no trees left to produce seedlings. If two dominate trees have overlapping canopies, the smallest one with the greatest defects is harvested. A forester must make the best decision in this situation. If a co-dominate or intermediate tree are overlapping with a dominate tree, typically the co-dominate and intermediate trees would be harvested. Also, if a landowner’s objectives are strictly timber, then all hardwoods would be harvested. If a landowner’s objective includes wildlife, then some mature healthy hardwoods should be left. In order for a tree to be harvested, in must have a DBH of 6" and merchantable height of 16’. Leave: Trees that should be left alone are trees that are the genetically best trees in the forest. Also, trees meet a specific objective of a landowner will be left alone. This would include flowering dogwoods for aesthetics, oaks for wildlife, or pines for timber. Also, all dead trees must be left because you can’t harvest, or deaden a dead tree. Typically, most pine trees that are too small to harvest are also left. You would rarely deaden a pine. Deaden: Trees that are to be deadened are trees that are in competition with what a landowner wants, but are too small to harvest. If timber is the primary objective, and a small dogwood is really close to that tree competing for water and nutrients, the forester may recommend to deaden that tree. Trees that are typically deadened are large trees called "wolf" trees. Wolf trees are large canopy trees that have no wildlife or timber value. With all these things in mind a forester is prepared to make the best decision for the landowner. Remember, you must not only look at the trees, but also the size class and the landowner’s objectives when making the best decision. Be sure to visit the following sites to learn more on timber stand improvement.
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