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Glossary of Terms

Anadromous Fish

Species of fish that mature in the sea and migrate into streams to spawn.

Aquifer

A body of rock that is saturated with water or transmits water. When people drill wells, they tap water contained within an aquifer.

Area

A discrete, specifically delineated space that is smaller, and in most cases much smaller, than a Ranger District.

Area of Critical Environmental Concern (ACEC)

Special Area designation established through the Bureau’s land use planning process (43 CFR 1610.7-2) where special management attention is needed to protect and prevent irreparable damage to important historical, cultural, or scenic values, fish and wildlife resources, or other natural systems or processes, or to protect life and safety from natural hazards. The level of allowable use within an ACEC is established through the collaborative planning process. Designation of an ACEC allows for resource use limitations in order to protect identified resources or values.

Aspect

The direction a slope faces. A hillside facing east has an eastern aspect.

ASQ (allowable sale quantity)

The amount of timber that may be sold within a certain time period from an area of suitable land. The suitability of the land and the time period are specified in the Forest Plan.

Assessment

The act of evaluating and interpreting data and information for a defined purpose.

AUM (animal unit month)

The quantity of forage required by one mature cow and her calf (or the equivalent, in sheep or horses, for instance) for one month.

Bark Beetle

An insect that bores through the bark of forest trees to eat the inner bark and lay its eggs. Bark beetles are important killers of forest trees.

Basal Area

The area of the cross section of a tree trunk near its base, usually 4 and 1/2 feet above the ground. Basal area is a way to measure how much of a site is occupied by trees. The term basal area is often used to describe the collective basal area of trees per acre.
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