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Uneven Aged Forest Management

In the article I wrote in the last newsletter, I discussed how a forester knows which trees to mark in a forest’s hardwood stand. One of my main points was that we manage a hardwood stand similar to that of a backyard garden. We mark trees for harvest that are the weed trees, allowing the good quality, healthiest and best formed trees, which forester’s call crop trees (or the vegetables in this example), to grow at their fastest rates over the life of the tree. Growing trees at their fastest rates is an important part of forestry and economics. The above actions are what most people call thinning a woodlot.

In hardwood stands, foresters also try to develop a stand of trees that eventually become uneven aged. Uneven aged stands of hardwood are those stands with three age classes of trees or more. We eventually want the forest to have seedlings, saplings, small poles, small sawtimber, and large sawtimber components within the forest as a whole. In other words, we want small trees, mid sized trees, and big trees. Managing a stand of timber to become uneven aged, allows for periodic thinnings or harvests usually every 10 to 15 years apart.

The main way we accomplish an uneven aged forest is to create canopy gaps (I know, another fancy forestry term, right?). Canopy gaps are simply a small opening in the forest overstory to allow sunlight to reach the forest floor. Canopy gaps are usually small openings that are only approximately 25-75 feet in diameter.

Canopy gaps are created by harvesting a large diameter tree in the woods with a large top, also called the crown. They are also created by harvesting a group of smaller diameter trees in a small area. The canopy gaps that are created allow for the remaining trees around the canopy gap to naturally drop its seeds in the gap to establish regeneration of hardwood seedlings. The new sunlight that is on the forest floor will allow the seedlings to grow at a faster rate in the growing seasons. In time, these seedlings become saplings, then small poles, then small sawtimber, and eventually large sawtimber. Can you see the circle of life occurring? Usually, this all occurs without even sticking a tree spade in the ground.

Everytime a thinning, also known as a harvest, is done, canopy gaps are created on a portion of the stand to create new age classes of trees. If thinnings are conducted every 10 years; then over 50 years, these thinning would have created five age classes of trees. Good forest management and logging is creating a healthy, vigorous forest when done correctly.

Benefits of Uneven Aged Forest Management:

  • Periodic income to the landowner
  • High quality, high value timber stands
  • Healthy and vigorous forest remains
  • Most people like the looks of an all aged hardwood forest
  • Removes fewer trees and larger trees at each entry
  • Diversity within the woods
  • Increased stand structure favors certain wildlife species
  • Natural regeneration, (no handplanting of seedlings needed)

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