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Managing the Hardwood Woodlot:
When Should I Harvest My Trees?
One question private landowners often ask foresters is “when should I
harvest my trees?” The answer to such a question need not be overly difficult, but it does have to be thoroughly
thought out if proper woodlot management is to be followed. A forester can guide a landowner but the final decision
belongs to the landowner alone. Factors to be considered are the age of the trees, size of the trees, density of
the trees in the woodlot, current market conditions, how many trees you have to sell, species of trees, management
goals of the landowner, and financial needs of the landowner.
Let’s see how these factors affect a harvesting decision.
- Age: Age can be deciding factor, especially in certain
forest types like aspen (popple). Aspen is a short-lived tree, which usually grows in stands of about the same
age. Aspen also is very intolerant of shade. On good sites aspen will begin to deteriorate at about 50 years of
age, even earlier on poor sites. Failure to cut aspen when it reaches this stage will mean a reduction in the quality
and volume of the harvest, a reduced financial return, and less sprouting. If aspen is not cut, eventually it will
die out of a given woodlot, due to its need for sunlight.
- Size: In contrast, age is not a major factor in woodlots
containing dense hardwoods (maple, ash, beech, oak, cherry). The size and age of a tree are related, but not always.
Old trees sometimes have small diameters due to years of suppression by overtopping neighboring trees. In general,
it would be safe to say that the largest trees in a hardwood woodlot are the oldest. As a general guide, trees
with diameters (measured at 4 ½ feet above the ground - diameter breast height, DBH) of 22-26 inches are
ready for harvest. Trees with smaller diameters are usually saleable, but by cutting them you are sacrificing future
time sale revenue. On poor soils, however, trees may never reach large diameters so cutting smaller trees may be
necessary. A recent Cornell Cooperative Extension Publication (#180) entitled Timber Management For Small Woodlands
states the following facts. Keep in mind this deals only with hardwood woodlots (maple, beech, cherry, ash, etc.).
- At 10 to 14 inches DBH, hardwoods have a low value, but the rate at
which they are increasing in value is high, especially for fast growing trees with proper growing space.
- As a hardwood tree increases in diameter from 14 to 24 inches DBH, it
may nearly double in height, increase 4½ times in volume (135 to 630 board feet) and increase tenfold in
dollar value. If a market is available for veneer, its value may increase substantially more.
- At 14 to 20 inches DBH, hardwoods may double in value for each two inches
of growth in diameter as log grade improves with size and as growth in height continues. At a rate of two inches
every ten years, a tree will also double in value in ten years (a compound growth rate of seven percent, not including
inflation.)
- At 20 to 24 inches DBH, hardwoods increase substantially on a dollar
basis but because the grade has peaked, the rate at which their value is increasing may slow to a compound growth
rate of 3.5 percent or less. The increase in dollar value is mostly the result of the increase in volume.
- At 24 to 28 inches DBH, the dollar value continues to increase, but
change in grade and height are unlikely. Also, growth in diameter is typically low as the tree reaches biological
maturity.
- Density: On the other hand, there are times when harvesting
trees with diameters between 16-22 inches is necessary and proper. When a woodlot is too crowded, a reduction in
the number of trees per acre is needed. This could be an income producing thinning. In such a harvest the intent
would be to upgrade the overall quality of the woodlot, maintain a good growth rate on selected trees and to improve
the environment for new and young trees.
- Let’s consider the example of a crowded woodlot containing trees with
diameters ranging from 14-26 inches. A proper selective harvest would involve cutting some 24-26 inch diameter
trees. It would also involved cutting some 14-22 inch diameter trees. The decision as to which tress to harvest
would be based upon individual tree form, size, soundness, species, the tree’s location relative to adjacent trees,
and the goals of the landowner.
- In a crowded hardwood woodlot containing trees with diameters ranging
from 14-18 inches a selective harvest is still warranted. The criteria for choosing which trees to harvest are
the same as above.
- Current Market Conditions: Current market conditions also
affect when trees should be harvested. Some tree species have a relatively low market value. These species might
be better utilized as firewood. Sometimes the price for certain tree species may be down for a time. If the trees
can be held for a few years, waiting for higher prices is a good idea. If prices are unusually high you may want
to market some trees early.
- Number of Trees to Sell: The number of trees you have
to sell is important. There are minimum volumes of timber, which is not economical for timber buyers to buy. These
minimum volumes are flexible depending upon size and quality of the trees for sale, species for sale, and size,
location, and available markets of each individual timber producer
- Species: The value of some tree species is so low that
it isn’t worthwhile trying to sell them or continue to grow them unless they have high value for wildlife or aesthetics.
Some other species are valuable in one part of the state and not in another, due to distance to markets and low
volumes in given areas.
- Management Goals: Your goals should be the guiding light
to any decision about your woodlot. Harvesting trees should be a means to achieve your goals. For example, if your
goal is improved wildlife habitat, you may want to harvest your stand of 35-year-old aspen. If your desire is to
develop a sugar bush you might have a harvest to encourage the growth and development of tappable trees and to
get some money to buy sugaring equipment. In addition, the skid trails can be improved into access roads. To encourage
certain types of trees over other you may cut earlier or later than is customary.
- Financial Catastrophes: Sometimes the best-laid plans
must be laid aside or modified to deal with an emergency. This may necessitate an early harvest or a larger harvest
than originally intended.
Before selling any trees think it through first. Also, be sure you have legal title to the timber and know where
your property lines are. Spring and early fall, before freeze-up, are not good times to harvest trees. Harvesting
at these times will cause serious rutting and soil compaction.
As you can see, deciding which trees to harvest and when, takes some thought. It also necessitates the help of
a professional forester. The results of a poor decision will last many years. Call our forester at (231) 882-4391
for more information.
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