If your goal is timber production, you should select valuable species with large, straight stems as your crop trees. By removing trees that are competing with the crowns of your crop trees, space is created for the crop tree crown to grow. As your crop trees grow more leaves, they produce more photosynthate, which translates to more stem growth. . Larger tree stems translates to higher values at harvest time.
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Some trees are inherently more valuable for their wood qualities. Historically, black walnut and black cherry have been considered the most prized for their easily-worked and deep colored heartwood. Recently, premium white oak has commanded higher prices for its use in whisky and bourbon barrels.
While softwoods - in Virginia, most commonly loblolly or white pine - are commonly grown in plantations, hardwoods tend not to be planted. Hardwoods compete poorly with grass, are difficult to match well with specific sites, and if planted at a wide spacing, tend to have a lot of limbs.
Appalachian hardwoods readily regenerate naturally and can form dense stands of mixed species that are well-matched with the site. Within these stands, competition for light is intense. Taller and faster-growing trees will be the eventual winners, shading the smaller trees that eventually die off. CTR accelerates stand development by artificially removing the eventual losers. When crop trees are freed from competition, lower crown branches stay alive and their crowns expand into the empty space. Simply put, bigger crowns grow more wood.
CTR allows you to select taller trees with the highest value as your crop trees, which can result in increased economic gains. The best candidate crop trees have clear and straight stems, with no forks, wounds, or diseases. It is not necessary to select just the tallest, or dominant, trees as crop trees, but trees with small crowns that are clearly losing the race for light have less chance of responding vigorously to release.
Cull trees competing with the upper crowns of crop trees should be removed, but smaller understory trees close to the crop tree should be left. These smaller trees help suppress epicormic sprouts. Epicormic sprouts are formed on hardwood stems from suppressed buds, usually in response to a sudden increase in sunlight. Epicormic sprouts are considered a defect and decrease the value of a timber tree.
White oak is a highly sought-after species as it is used heavily by the bourbon and whiskey industry to produce staves for barrels. It is the only oak species in the Appalachians that can be used because its cellular structure allows oxygen to permeate and release contents into the drink of choice, giving it a unique color and taste.
In terms of space, tree crowns typically fill gaps in the canopy at a rate of 1/2 ft per year in each open direction.
White oaks up to 90 years old may respond vigorously to CTR.
On the same tree, leaves growing in the shade and leaves growing in the sun can look very different. Generally, shade grown leaves are larger and thinner. If the tree has leaves with lobes and sinuses, the sinuses are often shallower on a shade leaf.
Tree species vary greatly in their ability to tolerate shade. Some species, such as
eastern hemlock
and
American beech,
are shade tolerant and can survive in heavy shade. In contrast,
Virginia pine
is shade intolerant and does poorly in low light. Oak species generally fall in the middle regarding how much light they need and are considered intermediate in shade tolerance.
How crop tree release can help landowners grow high-quality timber with Dr David Carter (part 1).
look for high value species such as oaks, sugar maple, and walnut
select straight stems with few defects, especially first 17 feet
How crop tree release can help landowners grow high-quality timber with Dr David Carter (part 2).
crop trees can be selected based on dominance in the canopy
