Harvests should result in improved forest health. When short-term income is the only objective, forest health frequently is sacrificed. It is
important to write down your goals for your property. Ideally, you take the time to work with a forester to develop a management plan for
your property. Action which is based on a plan is more likely to accomplish your management goals.
Different trees have different strategies for success. Success can be defined as living long enough to perpetuate the species. Some
trees go for the light right away. They grow faster than their competitors to get the upper hand (or branch). Pioneer species such as
yellow poplar, black cherry, aspen, locust and some pines dominate the forest by using this strategy. They are usually (relatively) short-
lived. They are known as shade intolerant.
The other strategy is to wait for the shade intolerant trees to die of old age, and be ready to grow when they do. Sugar maple and eastern
hemlock are examples of this type of tree. They tend to be long-lived. They are known as shade tolerant.
Many species fall in the middle: neither shade tolerant nor intolerant. These include oaks, white pine and red maple. In addition, many
seedlings & saplings are quite shade tolerant at first, but become more intolerant as they get bigger. You can see that if the objective is
to regenerate part or all of your forest, the type of harvest must be appropriate for the species to be regenerated.
In general, a harvest should seek to:
1. Improve the quality of the trees growing. To do this, it is necessary to decide which trees you (landowner or forester) plan to
leave. It is important to do this before the chainsaws are fired up.
2. Remove trees which are unlikely to survive until the next harvest.
3. Improve wildlife habitat by creating openings, cover and food.
4. Pay attention to spacing and species of the trees being left.
Silviculture is the science of forest establishment, growth, management & renewal. Usually the objective is to mimic natural
disturbances such as the death of a single tree or the result of a windstorm.
The following methods are based on this science:
■ Improvement harvest. This is essentially weeding. Low quality, low value trees are cut so that the remaining trees have
more room and resources such as water, light, and soil nutrients.
■ Single tree selection. The idea is to mimic the death of a large tree. The result is a small opening in the forest. This method is used
for unevenaged management. It works well for shade-tolerant species such as hemlock & sugar maple. Disadvantages: It is really
easy to wind up in the “cut the best & leave the rest” pitfall; and trees to be harvested will be scattered. The latter results in lower
production for the logger (who is trying to make a living at this) and more potential for damage to residual trees.
■ Group selection. A patch of trees is removed. The patch should be at least twice as wide as the height of the trees growing there. For
example, if the trees are about 100 feet tall, the patch should be at least 200 feet across. This method can be used to convert
evenaged forest to unevenaged. Because the cleared area is large enough to allow direct sunlight to reach the forest floor, it can be
used to regenerate shade intolerant species such as yellow poplar (tulip tree) or black cherry. It requires patience. The idea is to
harvest about 1/3 of the area each time, at intervals long enough to result in the establishment of different age classes, thus converting
evenaged stands to unevenaged ones.
■ Shelterwood. This method is used to regenerate stands of heavy-seeded species such as oak or hickory. The best quality trees are
left to provide seed to start the new forest. All others are removed, so that adequate light reaches the forest floor to cause seeds to
germinate and seedlings of the desired species to flourish. Usually 50-70% of the canopy is removed. Shelterwoods are often
referred to as “two-step” or “three step” depending on how many harvests will occur before the overstory is removed and the new forest
is left to grow. Shelterwoods can result in two-aged stands if the seed producing trees are not removed.
■ Seedtree. This method is used to regenerate light-seeded species such as conifers (pine, spruce, hemlock, larch, etc.) and
hardwoods such as yellow poplar, maples birch, etc. It works well for shade intolerant species that need full sunlight to regenerate
successfully. The new stand will be evenaged.
■ Clearcut. If an adequate number of seedlings of the desired species are present, the best practice may be to remove the overstory
and let ‘er grow. Clearcutting has gotten a bad name because in the past it was used indiscriminately. Consider this: try changing a
sparkplug in your car with a screwdriver. It won’t work. You need a particular tool to do the job. Clearcutting is a tool to regenerate
shade intolerant species.
|Because today’s forests originated from
clearcuts, they are evenaged. That is to say,
the trees in these forests are within plus or
minus 20 years of the average age. For
example, if the average age in a stand is 100
and most of the trees in that stand are
between 80 & 120 years old, it would be
considered evenaged. Trees of a given
species in an evenaged forest will have
similar height but be quite different in
The alternative to evenaged management is
unevenaged management. In unevenaged
management, trees of many different ages
are present, from seedlings to mature trees.