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A Woodlot Thinning Model:
Crop Tree Release Method
It is important for a woodlot owner to know when a woodlot needs a thinning
and which trees should be removed. Equally important is the method or procedure used to thin the woodlot. By following
a systematic thinning schedule, a landowner can save time and effort, provide for an even supply of firewood, and
develop a healthier woodlot with better quality trees. Such a system also insures that the whole area to be thinned
actually gets thinned.
The following text outlines a systematic procedure to thin a woodlot. It takes a woodlot of about 10 acres on fairly
fertile soils to provide an “average” homeowner with a yearly supply of firewood. Woodlots on smaller acreages
should follow the same procedure but a yearly supply of firewood cannot be expected. Alternate sources of firewood
may be necessary until a thinning is needed again.
Step #1: Cut in a simple system of access roads
Use the trees cut while making the access roads as your first year's supply of firewood. These access roads need
only be wide enough to allow easy passage of your equipment (usually 10-12 feet). Make sure the turns are not too
sharp or numerous. Cut the stumps low. Keep the access road at least 100 feet from the edge of the woodlot. If
roads are too close to the woodlot edge, you will need more road. Forget about the existence of any dead or downed
trees for the time being, unless they represent a safety hazard. Cutting dead trees does not improve the growth
of living trees. It may also mean the loss of food and habitat for some wildlife species. In this case, “cleaning
up” the woodlot might mean “cleaning out” some wildlife.
Step #2: Divide your woodlot into equal compartments
Each compartment should be at least one acre in size but no more than 5 acres. Most woodlot owners can only thin
about 3 acres a year. This method requires going through the entire woodlot during the first half of the thinning
rotation. Concentrate only on releasing the best “crop trees" by cutting poor quality or undesirable trees
competing with them. Once that is done, start over and “fine tune” each compartment thinning wherever necessary
to reduce the number of trees to the proper level. Under proper management, a woodlot needs to be thinned every
8-15 years. If your woodlot is so large that it cannot be thinned in 15 years, you may want to consider getting
help, forming a partnership, or thinning all or part of your woodlot by way of a commercial firewood sale. Larger
compartments will also be in order. Make sure it takes no longer than 15 years to thin your woodlot. Ten year rotations
are probably the best to follow. Mark the boundaries of each compartment with plastic ribbon or paint. Be sure
you know where your property boundaries are. Example: A 10-acre woodlot on a 10-year thinning rotation requires
five compartments each two acres in size. Parts of some woodlots are more dense than other areas. If this situation
exists, thin the dense areas first.
Step #3: Select about 80 of the best trees per acre in compartment #1
These “crop trees” are those of the best form and highest timber value species. Remove on at least two sides any
trees whose crowns are touching the crop trees. Crop trees should be spaced about every 20-30 feet. Disregard any
other trees not affecting the crop trees no matter how poor, unless they represent a hazard. If compartment #1
does not supply enough firewood, move on to compartment #2. It may help to tie ribbons on the crop trees to aid
in spacing and selection. Continue on each year until all the compartments have been treated.
NOTE: Do not remove any sound trees with diameters of 12 inches or more. Save these for a future
timber sale even if they do interfere with another “crop tree”.
Step #4: Evaluate your woodlot
Your woodlot has now been systematically thinned providing as steady a supply of firewood as possible. At this
time, have a professional forester evaluate the woodlot to see if a timber sale is needed. If a timber sale is
needed and undertaken, your access roads will help minimize logging damage. Cut up the tree tops for firewood following
the sale, then start your second thinning rotation. If a timber sale is not needed, start your thinning schedule
over.
NOTE: This document is designed to describe one system of thinning a woodlot. Refer to other documentation
on why a woodlot should be thinned and how to choose trees for cutting, or call us at (231) 882-4391 for more information.
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