a cultural treatment made to reduce stand density of trees primarily to improve growth, enhance forest health, or recover potential mortality; types of thinning include the following:

—chemical thinning the killing of unwanted trees by using an herbicide, e.g., including band or frill girdling

—crown thinning the removal of trees from the dominant and codominant crown classes in order to favor the best trees of those same crown classes —synonym thinning from above, high thinning

—free thinning the removal of trees to control stand spacing and favor desired trees, using a combination of thinning criteria without regard to crown position

—low thinning the removal of trees from the lower crown classes to favor those in the upper crown classes —synonym thinning from below

—mechanical thinning the thinning of trees in either even- or uneven-aged stands, involving removal of trees in rows, strips, or by using fixed spacing intervals —synonym geometric thinning

—selection thinning the removal of trees in the dominant crown class in order to favor the lower crown classes —synonym dominant thinning This definition last updated 09/25/2008