Items starting with I


Interior Board of Land Appeals

Igneous Rock

Rocks formed when high temperature, molten mineral matter cooled and solidified.


Interim Management Policy

IMPLAN (Impact Analysis for Planning)

The input-output model used by the USDA Forest Service to estimate economic effects by tracing the interrelationships between producers and consumers in an economy as measured by jobs and income

Implementation Decisions

Decisions that take action to implement land use plan decisions. They are generally appealable to IBLA under 43 CFR 4.40.

Implementation Plan

A site-specific plan written to implement decisions made in a land use plan. An implementation plans usually selects and applies best management practices to meet land use plan objectives. Implementation plans are synonymous with 'activity' plans. Examples of implementation plans include interdisciplinary management plans, habitat management plans, and allotment management plans.

Indian tribe (or tribe)

Any Indian group in the conterminous United States that the Secretary of the Interior recognizes as possessing tribal status (listed periodically in the Federal Register).

Indicator Species

A plant or animal species related to a particular kind of environment. Its presence indicates that specific habitat conditions are also present.

Indigenous Species

Any species of wildlife native to a given land or water area by natural occurrence.

Individual Tree Selection

The removal of individual trees from certain size and age classes over an entire stand area. Regeneration is mainly natural, and an uneven aged stand is maintained.


A parcel of land in other ownership (State, private, other Federal agency) surrounded by National Forest System land.

Initial attack

This term applies to an aggressive suppression action consistent with firefighter and public safety and with protecting various resource values.

Instream Flow

The quantity of water necessary to meet seasonal stream flow requirements to accomplish the purposes of the National Forests, including, but not limited to fisheries, visual quality, and recreational opportunities.

Integrated Pest Management (IPM)

IPM evaluates alternatives for managing forest pest populations, based on consideration of pest-host relationships.

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