Forests are dynamic, always growing and changing. They can be new, vigorous, old or dying, or a combination of these conditions. They can include just a few or many tree species.
Forest managers work to imitate nature, to a great degree, with silviculture. The imitation involves creating the favorable conditions that at times occur naturally in the forest.
For instance, sometimes wind, fire, ice storms or infestations by insects or diseases can kill a forest in short time. When the forest regrows, the new trees are all about the same age. This type of forest is called "even-aged."
Other times, a forest may grow for many years with only small groups or individual trees dying. This provides open spaces that soon will be filled by young trees.
Even-aged management is a growth and harvest cycle. Periodically, a portion of a forest is harvested with most trees removed. Some trees may be left to benefit wildlife or improve the scenery, but this is still the most visually dramatic harvest style. The openings created in a forest may be disturbing when first viewed, but regeneration begins immediately and is a quick rebuilder. Young trees regenerate from seeds, stump and root sprouts, or from plantings. As trees grow, the recent harvest becomes less noticeable. The trees grow rapidly. In a few years, the area will begin to appear more like the surrounding forest.
Uneven-aged management creates a forest with three or more aged classes of trees. Properly managed, the area will always contain large, medium and small trees. Only a few trees are harvested each cutting entry.
In uneven-aged management, trees are individually selected for cutting throughout the forest. New trees begin in the newly-created openings and in a few years become established in the small openings and under the existing canopy of older, larger trees.
Both even-aged and uneven aged systems are valuable and viable in the management of our forests.
Information Furnished by U.S. Forest Service