Items starting with T


Threatened and Endangered


A National Forest's annual goals for accomplishment for natural resource programs. Targets represent the commitment the Forest Service has with Congress to accomplish the work Congress has funded, and are often used as a measure of the agency's performance.


Total Maximum Daily Load

Temporary road or trail

A road or trail necessary for emergency operations or authorized by contract, permit, lease, or other written authorization that is not a forest road or trail and that is not included in a forest transportation atlas.

Temporary roads

Roads authorized by contract, permit, lease, or emergency operation, not intended to be a part of the forest transportation system and not necessary for long-term resource management.

thermal cover

Cover used by animals against weather. For elk, thermal cover can be found in a stand of coniferous trees at least 40 feet tall with a crown closure of at least 70%.


(a) The cutting down and/or removing of trees from a forest to lessen the chance of a ground fire becoming a crown fire; a method of preparing an area so that a prescribed fire can be more easily controlled. Thinning influences the available amount of fuel and fuel arrangement, and it can indirectly affect fuel moisture content and surface wind speeds. (b) A culture treatment made to reduce stand density of trees primarily to improve growth, enhance forest health, or recover potential mortality.


A cutting made in an immature stand of trees to accelerate growth of the remaining trees or to improve the form of the remaining trees.

Threatened Species

1) Any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range, and 2) as further defined by the Endangered Species Act of 1973.

timber classification

The classification of forested lands into land management alternatives according to how the land relates to management of the timber resource there.

Timber harvest

The volume of trees with commercial value that are cut and

Timberland (commercial forest land)

Land suitable for producing timber crops and not withdrawn from timber production by statute or administrative regulation. The typical minimum level of productivity is 20 cubic feet per acre per year.

Total Maximum Daily Load (TMDL)

An estimate of the total quantity of pollutants (from all sources: point, non-point, and natural) that may be allowed into waters without exceeding applicable water quality criteria

tractor logging

A logging method that uses tractors to carry or drag logs from the stump to a collection point.


A route 50 inches or less in width or a route over 50 inches wide that is identified and managed as a trail.

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