Forest Thinning

Two men looking up at trees in a forest

Forest thinning may be the appropriate management tool if you want to improve timber production, increase wildlife, or grow vigorous, healthy trees on your property.

Thinning rates for your wooded area depend on your goals, the type of wooded site, and the current condition and number of trees per acre.

Commercial thinning, or timber harvest, is an excellent forest and wildlife management tool if it is planned and administered properly. Thin your stand by carefully selecting and removing trees of marketable size and quality. Income from the sale can be used to accomplish other habitat projects.

If a timber harvest is not an option, then a noncommercial thinning, or timber stand improvement (TSI), can be performed to improve forest health.

Timber Stand Improvement (TSI)

TSI is the removal of selected trees from a timber stand to improve the health and growth of the remaining trees that may or may not be harvested in the future. As the name implies, this practice is conducted on forested sites where improving timber production is a priority. However, it is also used to promote forest health and increase wildlife habitat.

Most unmanaged timber stands become overcrowded, causing a shortage of water, nutrients, and sunlight for all trees. TSI reduces competition in a stand and allows you to decide which trees to keep based on your management goals.


Proper spacing of trees is the key to any TSI. Trees too closely spaced will soon become crowded, slowing their growth. Trees spaced too far apart waste growing space and encourage larger crowns at the expense of taller, straighter trunks.

To estimate the best distance between trees in a stand, measure one or several trees at a height of 4½ feet above the ground — a measurement known as “diameter at breast height,” or DBH. Multiply the average DBH (in inches) by two and use that number as the distance in feet to leave between trees. For example, if a tree is 11 inches in diameter, multiply by two to learn that 22 feet is the proper spacing to leave between that tree and the trunk of its nearest competitor tree.


Determine and adjust how many trees to cut according to your objectives. To manage forest stands for maximum timber benefit, contact a professional forester or skilled TSI contractor to help you outline and implement a more precise forest management plan.

Choosing trees

The most important trees to leave uncut are the trees with the best health, growth form, and value. These “crop trees” will live longer, provide the greatest food value for wildlife, and often have the highest value as wood products when mature.

Forested area with small downed trees on the ground
Leaving trees where you drop them creates wildlife cover.
MDC staff

Leave these trees for wildlife habitat:

  • Wolf trees: those with a short trunk but wide, spreading crown. These are especially important if they produce large amounts of hard mast (acorns and nuts) and are in an area dominated primarily by small trees that have not reached mast-producing age. Leave at least one for every two acres.
  • Den trees: those with an opening leading into a hollow interior
  • Tall, fruiting trees: including hackberry, black cherry, mulberry, black gum, and persimmon

Keep trees that will be removed in future thinning if they can fill growing space in the meantime. This leaves the least desirable surplus trees, which can be cut for firewood or other purposes.

Characteristics of Surplus Trees:

  • Poor-quality wood due to species of the tree
  • Multiple sprouts from one stump
  • Swellings or bumps on the trunk indicating internal damage
  • Fire scars or other damage to the trunk
  • Many wide-spreading branches low on the trunk