Glossary of Terms

treatment area

The site-specific location of a resource improvement activity.tree opening- An opening in the forest created by even-aged silvicultural practices.


See Indian tribe.

TSI (Timber Stand Improvement)

Actions to improve growing conditions for trees in a stand, such as thinning, pruning, prescribed fire, or release cutting.

type conversion

The conversion of the dominant vegetation in an area from forested to non-forested or from one species to another.


United States Code

Unauthorized road or trail

A road or trail that is not a forest road or trail or a temporary road or trail and that is not included in a forest transportation atlas.


A burn by a surface fire that can consume ground vegetation and "ladder" fuels.


The trees and woody shrubs growing beneath the over story in a stand of trees.

uneven-aged management

Actions that maintain a forest or stand of trees composed of intermingling trees that differ markedly in age. Cutting methods that develop and maintain uneven-aged stands are single-tree selection and group selection.

unregulated harvest

Tree harvest that is not part of the allowable sale quantity (ASQ). It can include the removal of cull or dead material or non-commercial species. It also includes volume removed from non-suitable areas for research, to meet objectives other than timber production (such as wildlife habitat improvement), or to improve administrative sites (such as campgrounds.)

unsuitable lands

Forest land that is not managed for timber production. Reasons may be matters of policy, ecology, technology, silviculture, or economics.

Use, allowable

An estimate of proper range use. Forty to fifty percent of the annual growth is often used as a rule of thumb on ranges in good to excellent condition. It can also mean the amount of forage planned to be used to accelerate range rehabilitation.

variety class

A way to classify landscapes according to their visual features. This system is based on the premise that landscapes with the greatest variety or diversity have the greatest potential for scenic value.

vegetation management

Activities designed primarily to promote the health of forest vegetation for multiple-use purposes.

vegetation type

A plant community with distinguishable characteristics.

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