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Definitions I - M

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igneous rock Rocks formed with high temperature, molten mineral matter cooled and solidified. (FS People's Glossary of Eco Mgmt Terms)
indicator species A plant or animal species related to a particular kind of environment.  Its presence indicates that specific habitat conditions are also present. (FS People's Glossary of Eco Mgmt Terms)
indigenous (species) Any species of wildlife native to a given land or water area by natural occurrence. (FS People's Glossary of Eco Mgmt Terms)
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. (FS People's Glossary of Eco Mgmt Terms)
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. (FS People's Glossary of Eco Mgmt Terms)
integrated pest management (IPM)  A systematic approach that uses a variety of techniques to reduce pest damage or unwanted vegetation to tolerable levels.  IPM techniques may include natural predators and parasites, genetically resistant hosts, environmental modifications, and when necessary and appropriate, chemical pesticides or herbicides. (FEMAT, IX-16)
interdisciplinary team A group of individuals with varying areas of specialty assembled to solve a problem or perform a task.  The team is assembled out of recognition that no one scientific discipline is sufficiently broad enough to adequately analyze the problem and propose action. (FEMAT, IX-17)
intermediate cut The removal of trees from a stand sometime between the beginning or formation of the stand and the regeneration cut.  Types of intermediate cuts include thinning, release, and improvement cuttings. (FS People's Glossary of Eco Mgmt Terms)
intermittent stream a) Any nonpermanent flowing drainage feature having a definable channel and evidence of scour or deposition.  This includes what are sometimes referred to as ephemeral streams if they meet these two criteria. (FEMAT, IX-16)

b) A stream that flows only at certain times of the year when it receives water from streams or from some surface source, such as melting snow. (FS People's Glossary of Eco Mgmt Terms)

Intermountain Region The portion of the USDA Forest Service, also referred to as Region Four, that includes National Forests in Utah, Nevada, southern Idaho, and southwestern Wyoming. (FS People's Glossary of Eco Mgmt Terms)
irretrievable Applies to losses of production, harvest, or commitment of renewable natural resources.  For example, some or all of the timber production from an area is irretrievably lost during the time an area is used as a winter sports site.  If the use is changed, timber production can be resumed.  The production lost is irretrievable, but the action is not irreversible. (FSEIS Nov. 2000, Vol. I p.475)
irreversible A term that describes the loss of future options.  Applies primarily to the effects, or use of nonrenewable resources, such as minerals or cultural resources, or to those factors, such as soil productivity that are renewable only over long periods of time. (FSEIS Nov. 2000, Vol. I p.475)
key summer range The portion of a wildlife species' summer range that is essential for the animal's pre, post, and reproduction cycles.  Deer require "fawning areas" where does give birth and hide their fawns for an essential period of time in the spring. (FS People's Glossary of Eco Mgmt Terms)
key winter range That portion of big game's range where the animals find food and cover during severe winter weather. (FS People's Glossary of Eco Mgmt Terms)
ladder fuels Vegetation located below the crown level of forest trees which can carry fire from the forest floor to tree crowns.  Ladder fuels may be low-growing tree branches, shrubs, or smaller trees. (FS People's Glossary of Eco Mgmt Terms)
land class The topographic relief of a unit of land.  Land classes are separated by slope; this coincides with the timber inventory process.  The three classes used in the Forest Plan are defined by the following slope ranges 0 to 35 percent; 36 to 55 percent; and greater than 55 percent. (FS People's Glossary of Eco Mgmt Terms)
landing Any place on or adjacent to the logging site where logs are assembled for further transport. (FEMAT, IX-18)
landline The boundary lines for National Forest land. (FS People's Glossary of Eco Mgmt Terms)
landscape A heterogeneous land area with interacting ecosystems that are repeated in similar form throughout. (FEMAT, IX-18)
land use planning The process of organizing the use of lands and their resources to best meet people's needs over time, according to the land's capabilities. (FS People's Glossary of Eco Mgmt Terms)
late successional forest Forest seral stages which include mature and old-growth age class. (FSEIS Feb. 94, Glossary-9)
late successional reserves a) A forest in its mature and/or old-growth stages that is reserved under each option in the FEMAT report.  (See Old-growth forest and Succession.)  (FEMAT, IX-18)

b) Land allocation under the Northwest Forest Plan with the objective to protect and enhance conditions of late-successional and old-growth forest ecosystems that serve as a habitat for late-successional and old-growth forest related species, including the northern spotted owl.  Limited stand management is permitted, subject to review by the Regional Ecosystem Office. (S&G Jan 2001, p. 77)

life zones Areas or "belts" of land that have distinct plant and animal characteristics determined by elevation, latitude, and climate.  When ascending a high mountain, you will pass through these life zones.  Examples of life zones include the Upper Sonoran, where Cedar City is located and gramma grasses, sagebrush, and scattered pinyon juniper predominate, and the Transition zone, where Ponderosa pine is predominant. (FS People's Glossary of Eco Mgmt Terms)
litter layer (forest litter layer) The loose, relatively un-decomposed organic debris on the surface of the forest floor made up typically of leaves, bark, small branches, and other fallen material. (FEMAT, IX-18)
logging reside (slash) The residue left on the ground after timber cutting.  It includes unutilized logs, uprooted stumps, broken branches, bark, and leaves.  Certain amounts of slash provide important ecosystem roles, such as soil protection, nutrient cycling, and wildlife habitat. (FS People's Glossary of Eco Mgmt Terms)
LS/OG forest (or stand) Late-successional and/or old growth.  Forests or stands consisting of trees and structural attributes and supporting biological communities and processes associated with old-growth and /or mature forests. (FEMAT, IX-19)
M Thousand.  Five thousand board feet of timber can be expressed as 5M board feet. (FS People's Glossary of Eco Mgmt Terms)
macro climate The general, large scale climate of a large area, as distinguished from the smaller scale micro climates within it. (FS People's Glossary of Eco Mgmt Terms)
management action Any action undertaken as part of the administration of the National Forest. (FS People's Glossary of Eco Mgmt Terms)
mass movement/wasting The down slope movement of earth caused by gravity.  Includes but is not limited to landslides, rock falls, debris avalanches, and creep.  It does not, however, include surface erosion by running water.  It may be caused by natural erosional processes, or by natural disturbances (e.g., earthquakes or fire events) or human disturbances (e.g., mining or road construction). (FEMAT, IX-20)
matrix a) Federal lands outside of reserves, withdrawn areas, and Managed Late-Successional areas. (FEMAT, IX-20)

b) The least fragmented, most continuous pattern element of landscape; the vegetation type that is most continuous over a landscape. (FS People's Glossary of Eco Mgmt Terms)

mature stand A mappable stand of trees for which the annual net rate of growth has peaked.  Stands are generally greater than 80-100 years old and less than 180-200 years old.  Stand are, diameter of dominate trees, and stand structure at maturity vary by forest cover types and local site conditions.  Mature stands generally contain trees with a smaller average diameter, less age class variation, and less structural complexity than old-growth stands of the same forest type.  Mature stages of some forest types are suitable habitat for spotted owls.  However, mature forests are not always spotted owl habitat, and spotted owl habitat is not always mature forest. (FEMAT, IX-20)
MBF Thousand Board Feet (see board foot.) (FS People's Glossary of Eco Mgmt Terms)
mean annual increment of growth The total increase in size of volume of individual trees.  Or, it can refer to the increase in size and volume of a stand of trees at a particular are, divided by that are in years. (FS People's Glossary of Eco Mgmt Terms)
microclimate The suite of climatic conditions measured in localized areas near the earth's surface.  Microclimate variables important to habitat may include temperature, light, wind speed, and moisture. (S&G Jan 2001, p. 78)
middleground A term used in the management of visual resources, or scenery.  It refers to the visible terrain beyond the foreground where individual trees are still visible but do not stand out distinctly from the stand. (FS People's Glossary of Eco Mgmt Terms)
mineral soil Soil that consists mainly of inorganic material, such as weathered rock, rather than organic matter. (FS People's Glossary of Eco Mgmt Terms)
MIS (management indicator species) A wildlife species whose population will indicate the health of the ecosystem in which it lives and, consequently, the effects of forest management activities to that ecosystem.  MIS species are selected by land management agencies.  (See indicator species). (FS People's Glossary of Eco Mgmt Terms)
mission (of the USDA Forest Service) "To Care for the Land and Serve the People."  As set forth in law, the mission is to achieve quality land management under the sustainable multiple-use management concept to meet the diverse needs of people. (FS People's Glossary of Eco Mgmt Terms)
mitigating measures Modifications of actions that (1) avoid impacts by not taking a certain action or parts of an action; (2) minimize impacts by limiting the degree or magnitude of the action and its implementation; (3) rectify impacts by repairing, rehabilitating or restoring the affected environment; (4) reduce or eliminate impacts over time by preservation and maintenance operations during the life of the action; or (5) compensate for impacts by replacing or providing substitute resources or environments. (FEMAT, IX-21)
mixed stands A stand consisting of two or more tree species. (FS People's Glossary of Eco Mgmt Terms)
MM Million. (FS People's Glossary of Eco Mgmt Terms)
MMBF Million Board Feet (see board foot). (FS People's Glossary of Eco Mgmt Terms)
monitoring The process of collecting information to evaluate if objectives and anticipated or assumed results of a management plan are being realized or if implementation is proceeding as planned. (FEMAT, IX-21)
mortality Trees that were merchantable and have died within a specified period of time.  The term mortality can also refer to the rate of death of a species in a given population or community. (FS People's Glossary of Eco Mgmt Terms)
mosaic Areas with a variety of plant communities over a landscape, such as areas with trees and areas without trees occurring over a landscape. (FS People's Glossary of Eco Mgmt Terms)
mountain pine beetle A tiny black insect, ranging from 1/8 to 3/4 inch in size, that bores through a pine tree's bark.  It stops the tree's intake and transport of the food and nutrients it must have to stay alive, thus killing the tree. (FS People's Glossary of Eco Mgmt Terms)
multiple use

Management of the public lands and their various resource values so that they are utilized in the combination that will best meet the present and future needs of the American people.  Making the most judicious use of the land for some or all of these resources or related services over areas large enough to provide sufficient latitude for periodic adjustments in use to conform to changing needs and conditions.  The use of some land for less than all of the resources.  A combination of balanced and diverse resource uses that takes into account the long-term needs of future generations for renewable and nonrenewable resources, including, but not limited to, recreation, range, timber, minerals, watershed, wildlife and fish, and natural scenic, scientific, and historic values.  Harmonious and coordinated management of the various resources without permanent impairment of the productivity of the land and the quality of the environment.  This combination in not necessarily the one that will give the greatest dollar return or greatest unit output. (FEMAT, IX-22)

Last updated
 Monday, July 21, 2003

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