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Glossary of Terms

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advance reproduction: the young trees in the understory of a forest stand that will grow when the overstory trees are cut and removed.

aquifer: an underground geological formation or group of formations that contain water, a source of ground water for wells and springs.

ARD: annosus root disease: a root and butt disease which affects southern yellow pines and other coniferous species.

average annual mortality: Average annual volume of trees 5.0 inches d.b.h. and larger that died from natural causes during the intersurvey period.

average annual removals: Average annual volume of trees 5.0 inches d.b.h. and larger removed from the inventory by harvesting, cultural operations (such as timber-stand improvement), land clearing, or changes in land use during the intersurvey period.

average net annual growth: Average annual net change in volume of trees 5.0 inches d.b.h. and larger in the absence of cutting (gross growth minus mortality) during the intersurvey period.

atmospheric deposition: the addition of elements or substances found in the air to the surface of the earth.

backcross: mating first generation progeny with a parent or member of the parental stock; this process is commonly used when attempting to enhance genetic resistance to pest organisms.

basal area: The area in square feet of the cross section at breast height of a single tree, a group of trees, or all of the trees in a stand, usually expressed in square feet per acre.

basin: the entire area drained by a river and its tributaries.

benthic: of or pertaining to the bottom of a stream, lake, sea, or ocean.

biocontrol: the process of introducing, or augmenting the population of, one organism to mitigate the destructive activity of another (pest) organism.

biological control: see... biocontrol

biomass: The aboveground green weight of solid wood and bark in live trees 1.0 inch d.b.h. and larger from the ground to the tip of the tree. All foliage is excluded. The weight of wood and bark in lateral limbs, secondary limbs, and twigs under 0.5 inch in diameter at the point of occurrence on sapling-size trees is included but is excluded on poletimber and sawtimber-size trees.

bole: That portion of a tree between a 1-foot stump and a 4-inch top diameter outside bark (d.o.b.) in trees 5.0 inches d.b.h. and larger.

broad management class: Also referred to as “broad management type” or BMT, a classification of timberland based on forest type and stand origin.

BTB: black turpentine beetle; an insect pest of southern yellow pines.

BWA: balsam woolly adelgid; an insect pest primarily of Fraser fir which also affects balsam fir.

census water: Streams, sloughs, estuaries, canals, and other moving bodies of water 200 feet wide and greater, and lakes, reservoirs, ponds, and other permanent bodies of water 4.5 acres in area and greater.

centers: areas of destructive insect or disease pest activity which are clearly delimited by common, host-expressed symptoms.

channelization: the modification of a channel by clearing, excavation, realignment, lining, or other means to increase its capacity for water flow.

clearcutting: the removal of all the trees on a site for the purpose of utilization and to provide for regeneration of an even-aged stand of trees, usually of a species requiring full sunlight for proper development and growth.

commercial forest land: (see: Timberland).

commercial species:   Tree species currently or potentially suitable for industrial wood products.

contaminant: a constituent that can impair the use of water.

conveyance: a channel or passage for conduction or transmission, as a pipe, canal, conduit, or ditch.

cropland: Land under cultivation within the past 24 months, including orchards and land in soil-improving crops but excluding land cultivated in developing improved pasture. Also includes idle farmland.

cross: the process of mating genetically different parents or breeding stock so as to produce progeny.

d.b.h.: tree diameter at breast height, usually assumed to be 4.5 feet above ground level.

dependency ratio: a rough estimate of the number of dependents per worker. The ratio is computed by dividing the number of people who are most likely to be dependent (those under age 19 plus those over 64) by the number of people in the working-aged population (ages 19 through 64).

diameter class: A classification of trees based on tree d.b.h. Two-inch diameter classes are commonly used by Forest Inventory and Analysis, with the even inch as the approximate midpoint for a class. For example, the 6-inch class includes trees 5.0 through 6.9 inches d.b.h.

direct effect: economicresponse in an industry that results from a change in that industry’s output.

d.o.b. (diameter outside bark): Tree stem diameter including bark.

easement: an interest in real property that conveys use or other rights but not ownership.

ecological section: an area or region of land designated for study purposes that has distinct geology, landforms, soils, flora, and fauna that set it apart from surrounding geographic areas.

economic multiplier: see response coefficient.

ecotone: a transitional zone between two adjacent communities, containing species characteristic of both as well as other species occurring only within the zone.

employee compensation: wage and salary payments as well as benefits including health and life insurance, retirement payments, and any other non-cash compensation; includes all income to workers paid by employers (p. 229, MN IMPLAN 1997b).

endangered species: a species or subspecies in danger of extinction throughout all or a significant portion of its range, as rated and listed by the USDI FWS.

endemic (endemism): species restricted to a particular geographic area; for aquatic species, usually limited to one or a few small streams, a single drainage, or an ecological section.

environmental justice: the pursuit of equal justice and equal protection under the law for all environmental statutes and regulations without discrimination based on race, ethnicity, and/or socio-economic status. Presidential Executive Order No. 12898 (issued February 11, 1994) requires Federal agencies to respond to the issue of environmental justice by “identify[ing] and address[ing] disproportionately high and adverse human health or environmental effects of its programs, policies, and activities on minority and low income populations.”

estuarine: of or relating to an estuary, which is an inlet or arm of the sea, especially the lower portion or wide mouth of a river where salty tide meets freshwater current.

etiology: the process of assigning causes, origins, or reasons for the occurrence of pest problems.

evapotranspiration: loss of water from the soil, including that by direct evaporation and that by transpiration from the surfaces of plants.

even-aged management: timber management methods that result in the creation of forest stands in which all trees are essentially the same age.

extirpation: elimination of a species in part of its range.

exotic pest: a pest (see... pest) organism in an area in which it would not normally be found, but into which it has been moved by the action of humans, other animals, or abiotic forces. In common discussion, this term is used interchangeably with "introduced pest" and "non-native pest".

farm: Land on which agricultural operations are being conducted and sale of agricultural products totaled $1,000 or more during the year.

federal lands county: a county in which Federal lands made up 30 percent or more of the area in 1987.

fire-dependent: the characteristic of requiring periodic fire as part of the ecosystem.

floodplain: low, relatively flat land adjoining inland and/or coastal waters, which is subject to periodic flooding.

forest fragmentation: the breaking up of large, contiguous forested tracts into smaller or less contiguous tracts.

Forest Inventory and Analysis (FIA): a USDA Forest Service research program that periodically conducts a forest inventory for each State.

forest land:   Land that is at least 10 percent stocked by forest trees of any size, or formerly having had such tree cover, and not currently developed for non-forest use. The minimum area considered for classification is 1 acre. Forested strips must be at least 120 feet wide.

forest management type: A classification of timberland based on forest type and stand origin, consisting of:

forest type:   A classification of forest land based on the species forming a plurality of live-tree stocking. Major eastern forest-type groups are:

forest: an assemblage of woody vegetation typically attaining positions in a plant community at the tallest level; attains height and diameter growth of canopy-layer trees within established averages for the species.

forested tract size: The area of forest within the contiguous tract containing each Forest Inventory and Analysis sample plot.

fragmentation: “the process by which a landscape is broken into small islands of forest within a mosaic of other forms of land use or ownership--note e.g. islands of a particular age class (e.g., old growth) that remain within areas of younger-aged forest -- note fragmentation is a concern because of the effect of noncontiguous forest cover on connectivity and the movement and dispersal of animals in the landscape” - definition from John A. Helms, ed., 1998. The Dictionary of Forestry. The Society of American Foresters, Bethesda MD.

fresh water: water that contains less than 1,000 milligrams per liter (mg/L) of dissolved solids.

fungicides: chemicals used to kill unwanted fungi.

geomorphology: a science that deals with the land and submarine relief features of the earth’s surface and seeks a genetic interpretation of them; physiography.

gross growth: Annual increase in volume of trees 5.0 inches d.b.h. and larger in the absence of cutting and mortality. Gross growth includes survivor growth, ingrowth, growth on ingrowth, growth on removals before removal, and growth on mortality before death.

gross regional product (GRP): a measure of total income in a given area. The GRP includes employee compensation, property income, and proprietary income plus indirect business taxes. The GRP is equal to total value added and is the local or regional equivalent of the national measure of economic growth, the Gross Domestic Product.

growing stock: the volume of sound wood in cubic feet (ft) in trees that are at least 5.0 inches (in.) in diameter at breast height (d.b.h.), from a 1-ft stump to a minimum 4.0-inch top diameter (outside bark) of the central stem or to the point where the central stem breaks into limbs.

Growing-stock trees: Live trees of commercial species classified as sawtimber, poletimber, saplings, and seedlings. Trees must contain at least one 12-foot log or two 8-foot logs in the saw-log portion, currently or potentially (if too small to qualify), to be classed as growing stock. The log(s) must meet dimension and merchantability standards to qualify. Trees must also have, currently or potentially, one-third of the gross board-foot volume in sound wood.

growth/removals ratio: a ratio obtained by dividing volume of timber growth by volume of timber removals during a particular time period, usually 1 year.

hardwoods: Dicotyledonous trees, usually broadleaf and deciduous, which can be divided into two broad timber groups:

historic: relating to or existing in times of written history; Within the Assessment area, the historic period is considered to begin with the expedition of Hernando de Soto in the 1540’s.

HWA: hemlock woolly adelgid; an insect pest of hemlock.

hydric soil: a soil that is saturated, flooded, or ponded long enough during the growing season to develop anaerobic (oxygen-lacking) conditions that favor the growth and regeneration of hydrophytic vegetation.

hydrologic unit: a geographic area representing part or all of a surface drainage basin or distinct hydrologic feature as delineated by the Office of Water Data Coordination on State hydrologic unit maps; each hydrologic unit is identified by an eight-digit number; in this assessment, hydrologic units are also referred to as watersheds.

hydrologic unit code (HUC): an eight-digit code used to catalog watersheds.

hydrology: the science dealing with the study of water on the surface of the land, in soil and underlying rocks, and in the atmosphere.

idle farmland: Cropland, orchard, improved pasture, and farm sites not tended within the past 2 years, and currently less than 10 percent stocked with live trees.

infection court: area on a plant which has been preconditioned by either physical or biological agents to be more susceptible to invasion by disease causing agents.

impoundments: human-engineered and dammed lakes, ponds, and reservoirs.

improved pasture: Land currently improved for grazing by cultivation, seeding, irrigation, or clearing of trees or brush.

indicator species: a species of plant or animal whose presence or absence indicates the general health of the community upon which the species is most dependent. Generally, providing for the needs of the indicator species will also meet the needs of most other organisms in the community.

indirect effect: the economic effect that occurs when a producer purchases goods and services from another producer, who, in turn, also purchases goods and services.

induced effect: the economiceffect that occurs through the payment of wages to employees of directly or indirectly affected industries.

industrial wood: All roundwood products except fuelwood.

ingrowth: The net volume (or number) of trees that grow large enough during a specified year to qualify as saplings, poletimber, or sawtimber.

in-migration rate: the rate at which people move into a community or region over a given time period.

integrated pest management (IPM): a decisionmaking and action process incorporating biological, economic, and environmental evaluation of pest-host systems to manage pest populations.

interest community (community of interest): group of individuals belonging to an organization that has an identifiable set of interests.

introduced pest: see... exotic pest.

inventory elasticity: a measure of the responsiveness of harvest to changes in standing timber inventory.

karst: an area of irregular limestone in which erosion has produced fissures, sinkholes, underground streams, and caverns.

labor force: a group consisting of persons who are either working or looking for work.

labor market: a “place” in economic theory where labor demand and supply interact.

land area: The area of dry land and land temporarily or partly covered by water such as marshes, swamps, and river floodplains (omitting tidal flats below mean high tide), streams, sloughs, estuaries, and canals less than 200 feet wide, and lakes, reservoirs, and ponds less than 4.5 acres in area.

live trees: All living trees. All size classes, all tree classes, and both commercial and noncommercial species are included.

mast: the fruit of flowering trees used by wildlife for food.

mesic: describing sites with a moderate amount of moisture, which support plants that requiure a moderate amount of moisture.

metropolitan county: one that is included in an MA (see metropolitan area).

metropolitan statistical area (MSA): a Census Bureau-defined urbanized area of at least 50,000 inhabitants with a total metropolitan population of at least 100,000. Additional contiguous counties are included in the MSA if they meet certain requirements of commuting to the central counties and other selected requirements of metropolitan character (such as population density and percent urban).

mussel: an aquatic bivalve mollusk.

native species: species that is within its known historical range, and there is no evidence of humans having artificially introduced it.

natural open land: land that is mostly free of trees due to the ecological conditions of the site.

natural pine:   Stands that have not been artificially regenerated and with a southern yellow, white pine–hemlock, or other forest type.

neotropical migratory birds: birds which migrate to the neotropics (South and Central America and the Caribbean) during the winter, but breed and nest in North America.

net annual change: Increase or decrease in volume of live trees at least 5.0 inches d.b.h. Net annual change is equal to netannual growth minus average annual removals.

 net annual growth:   The net annual change in merchantable volume for a specific year in the absence of cutting (gross growth minus mortality for that specified year).

net volume: Gross volume of wood less deductions for rot, sweep, or other defect affecting use for timber products.

noncommercial species: Tree species of typically small size, poor form, or inferior quality that normally do not develop into trees suitable for industrial wood products.

nonforest land:   Land that has never supported forests and land formerly forested where timber production isprecluded by development or other uses.

nonmetropolitan county: a county lying outside a defined metropolitan area (see metropolitan area).

non-native pest: see... exotic pest.

nonpoint source pollution: a diffuse source of pollution. May originate from atmospheric deposition as well as surface and sub-surface runoff.

nonstocked forest land: Timberland less than 10 percent stocked with growing-stock trees.

NPV: nucleopolyhedrosis virus; a type of virus often used in biological control efforts.

old-growth stand: a stand of trees characterized by a diversity of tree species in several size classes, advanced age, downed logs and snags, large canopy trees, tree fall gaps, undisturbed soils, and other plants and animals that prefer old growth.

other forest land: Forest land other than timberland and productive reserved forest land. It includes available and reserved forest land which is incapable of producing annually 20 cubic feet per acre of industrial wood under natural conditions, because of adverse site conditions such as sterile soils, dry climate, poor drainage, high elevation, steepness, or rockiness.

other removals:   The growing stock volume of trees removed from the inventory by cultural operations such as timber stand improvement, land clearing, and other changes in land use that result in the removal of the trees from timberland.

out-migration rate: rate at which people move out of a county or region over a given period of time.

ownership: The property owned by one ownership unit, including all parcels of land in the United States:

pathogen: any biotic or viral disease causing agent.

perennial stream: streams that flow throughout the year.

pest: insects, microorganisms, nematodes, and atmospheric pollutants and other noninfectious disease-causing agents considered to be detrimental to achieving resource management objectives.

pesticide: a) any substance or mixture of substances intended to prevent, destroy, repel, or mitigate any pest; or, b) any substance or mixture of substances intended for use as a plant regulator, defoliant, or desiccant.

pheromone: an chemical secreted by one organism to influence the physiology or behavior of another organism of the same species or, in some cases, members of another species.

pine plantation:   Stands that have been artificially regenerated by planting or direct seeding and with a southern yellow pine, white pine-hemlock, or other forest type.

point source pollution: contamination or impairment from a known specific point of origination, such as sewer outfalls or pipes.

poletimber: trees 5.0 to 8.9 in. d.b.h. for softwoods and 5.0 to 10.9 in. for hardwoods.

population density: the number of individuals of a species per unit area.

prehistoric: relating to or existing in times predating written history. This term generally refers to those North American cultures in existence prior to A.D. 1540.

price elasticity: a measure of the sensitivity of supply and demand to changes in price. If price elasticity is low, a large change in price will lead to a small change in supply.

primary wood-using plants: Industries receiving roundwood or chips from roundwood for the manufacture of products such as veneer, pulp, and lumber.

productive-reserved forest land: Forest land sufficiently productive to qualify as timberland but withdrawn from timber utilization through statute or administrative regulation.

proprietary income: income from self-employment.

province: in the context used in the report, a geographic area having particular geologic and landform characteristics.

quarantine: enforced isolation or restriction of free movement of plant or animal materials to prevent the spread of pests from one area to another.

rangeland: Land on which the natural vegetation is predominantly native grasses, grasslike plants, forbs, or shrubs valuable for forage, not qualifying as timberland and not developed for another land use. Rangeland includes natural grassland and savannah.

rare species: any native or once-native species of wild plant or animal that exists in small numbers and has been determined to need monitoring (may include peripheral species).

rare: a classification reflecting a species’ scarcity in a given area. Rare plants and animals (and eventually communities) are assigned rarity ranks according to The Nature Conservancy’s global ranking system.

real price: price of products adjusted for the effects of general inflation. Adjustments were made using the Gross Domestic Product deflator from the Economic Report of the President.

reforestation: Area of land previously classified as forest that is regenerated by seeding, planting trees, or natural regeneration.

regeneration cutting: a cutting that provides conditions necessary for the establishment of a new stand of forest trees.

removals: the net volume of growing stock trees removed from the inventory by harvesting or cultural operations such as timber stand improvement (e.g., thinning), land clearing, or change in land use.

Renewable Resources Planning Act (RPA): passed by Congress in 1974 and updated in 1993, this law requires the Forest Service to conduct an assessment of the Nation’s forests every 10 years (and to provide updates every 5 years).

reserved timberland: (See: Productive-reserved forest land).

reservoir: an artificial lake in which water is impounded for a variety of uses.

response coefficient: effects on jobs, wages, or incomes per unit of production or output such as per million dollars of mineral extracted, million board feet harvested, or million recreation trips.

riparian zone/riparian area: the area of land on either side of streams, channels, rivers, and other water bodies. These areas are normally distinctly different from the surrounding lands because of unique soil and vegetation characteristics (e.g., wetter soil than adjacent soil conditions where aquatic vegetative communities thrive).

riparian: describing lands associated with bodies of water.

rotation age: the age at which an even-aged stand of trees is scheduled for harvest or regeneration cutting (the actual age depends on management objectives, the tree species involved, and local site conditions).

rotten trees: Live trees of commercial species that do not contain at least one 12-foot saw log, or two noncontiguous saw logs, each 8 feet or longer, now or prospectively, primarily because of rot or missing sections, and with less than one-third of the gross board-foot tree volume in sound material.

rough trees: Live trees of commercial species that do not contain at least one 12-foot saw log, or two noncontiguous saw logs, each 8 feet or longer, now or prospectively, primarily because of roughness, poor form, splits, and cracks, and with less than one-third of the gross board-foot tree volume in sound material; and live trees of noncommercial species.

roundwood:   Logs, bolts or other round sections cut from trees for industrial or consumer uses.

roundwood products: Any primary product such as lumber, poles, pilings, pulp, or fuelwood, that is produced from roundwood.

salvable dead trees: Standing or downed dead trees that were formerly growing stock and merchantable. Trees must be at least 5.0 inches d.b.h. to qualify.

sanitation: preferential removal of most symptomatic materials from a disease infected or insect infested stand during routine or extraordinary stand manipulation.

saplings:   Live trees 1.0 to 5.0 inches d.b.h.

savannah: an assemblage of woody vegetation having a scattered distribution with an understory dominated by grasses and forbs maintained by recurring fire; height and diameter growth of canopy-layer trees may be stunted by environmental factors (i.e., weather, shallow soils) or within established averages for the species.

saw log: A log meeting minimum standards of diameter, length, and defect, including logs at least 8 feet long, sound and straight, and with a minimum diameter inside bark for softwoods of 6 inches (8 inches for hardwoods).

saw-log portion: That part of the bole of sawtimber trees between a 1-foot stump and the saw-log top.

saw-log top: The point on the bole of sawtimber trees above which a conventional saw log cannot be produced. The minimum saw-log top is 7.0 inches in diameter outside bark (d.o.b.) for softwoods and 9.0 inches d.o.b. for hardwoods.

sawtimber: trees with a 9 in. d.b.h. and larger for softwoods and 11 in. d.b.h. and larger for hardwoods.

sawtimber volume: Growing-stock volume in the saw-log portion of sawtimber-size trees in board feet (International 1/4-inch rule).

section 404 permit: a permit issued under section 404 of the CWA for activities that require dredging and filling of materials within waters of the United States.

seedlings: Trees less than 1.0 inch in d.b.h. and greater than 1 foot tall for hardwoods, greater than 6 inches tall for softwoods, and greater than 0.5 inch in diameter at ground level for longleaf pine.

seedtree: an even-aged silvicultural harvest and regeneration system that removes most of the mature stems. A number of trees (generally, 4 to 10 per acre, singly or in groups) are retained to provide seeds to establish the new stand.

select red oaks: A group of several red oak species composed of cherrybark, Shumard, and northern red oaks. Other red oak species are included in the "other red oaks" group.

select white oaks: A group of several white oak species composed of white, swamp chestnut, swamp white, chinkapin, Durand, and bur oaks. Other white oak species are included in the "other white oaks" group.

semiochemical: any chemical (including pheromones) involved in the interaction between organisms.

sensitive species: a term used for species of special concern by some States.

shelterwood cutting: a regeneration cutting method that removes the overstory stand in two or more operations, spaced in time.

shelterwood: an even-aged silvicultural harvest and regeneration system that gradually removes most or all trees in a series of partial cuttings, which resemble heavy thinning. Regeneration establishes under the protection of partial canopy cover.

silviculture: “the art and science of controlling the establishment, growth, composition, health, and quality of forests and woodlands to meet the diverse needs and values of landowners and society on a sustainable basis” - definition from John A. Helms, ed., 1998. The Dictionary of Forestry. The Society of American Foresters, Bethesda MD.

single-tree selection: an uneven-aged silvicultural harvest system that removes selected trees to create canopy gaps. Trees selected for removal may be healthy or diseased, depending on the goals of the landowner.

site class: A classification of forest land in terms of potential capacity to grow crops of industrial wood based on fully-stocked natural stands.

softwoods: Gymnosperms; in the order Coniferales, usually evergreen, having needles or scalelike leaves.

SPB: Southern pine beetle; an insect pest of southern yellow pines.

species density: total number of species per square mile.

species richness: the total number of native species within a particular region.

stand age: The average age of dominant and codominant trees in the stand

stand origin: A classification of forest stands describing their means of origin:

stand-size class: A classification of forest land based on the diameter class distribution of live trees in the stand:

State Section 305(b) reports: water quality reports submitted every 2 years by each State to EPA that indicate the status of water quality within the state; EPA submits a report to Congress based on these state reports.

stocking: The degree of occupancy of land by trees, measured by basal area or the number of trees in a stand and spacing in the stand, compared with a minimum standard, depending on tree size, required to fully utilize the growth potential of the land Table below shows the density of trees and basal area per acre required for full stocking:

d.b.h. class

trees per acre for full stocking

basal area per acre


































stream reach: a segment of a stream.

streamside management zone (SMZ): a designated area that consists of the stream itself and an adjacent area ofvarying width where management practices that might affect water quality, fish, or other aquatic resources are modified. The SMZ acts as a filter and absorption zone for sediments, maintains shade, protects riparian and terrestrial riparian habitat; protects channels and stream banks, and promotes floodplain stability.

stressor: pressure or change brought upon an ecosystem by pollution sources such as contaminants and toxins.

stumpage price: the price paid by a logger to a landowner for standing timber.

Subregional Timber Supply (SRTS) model: a model developed by Robert C. Abt, North Carolina State University, Durham, NC. The model uses a timber supply framework consistent with the RPA models but tracks inventory and growth trends by individual FIA survey unit or subregion as well as by ownership category (forest industry and nonindustrial private forest).

surface water: an open body of water such as a stream or lake.

survivor growth: The merchantable volume increment on trees 5.0 inches d.b.h. and larger in the inventory at the beginning of the year and surviving to the end of the year.

threatened species: a species or subspecies that is likely to become endangered throughout all or a significant portion of its range and listed as such by the USDI FWS.

timber dependency: as used in this report, the percentage of all earnings in a county represented by timber-related earnings (SIC codes 08 and 24 of the U.S. Bureau of Economic Analysis).

timber market zones: geographic areas used as a basis for analyzing the economic effects of timber sale programs on national forests. The zones comprise counties with national forest lands plus those counties that have mills that purchase national forest timber.

timberland: forested land that is capable of producing crops of industrial wood at a rate of at least 20 cf/ac per year and has not been withdrawn from timber production. (Some forest lands are not classified by the FIA as timberland because they are unproductive and some—such as national parks and wildernesses—because by law, they are off limits to harvesting.)

timber-significant county: a county where the forest products industry represents a significant share of the economy.

timber products: Roundwood products and byproducts.

timber removals: The merchantable volume of trees removed from the inventory by harvesting, cultural operations such as stand improvement, land clearing, or changes in land use.

total income: the sum of employees’ compensation, proprietor’s income, and property type income.

total industrial output (TIO): the value of production by industry for a given time period. Output can be measured by the total value of purchases by intermediate and final consumers, or by intermediate outlays plus value added. Output can also be thought of as value of sales plus or minus inventory (p. 233, MN IMPLAN 1997b).

total maximum daily load (TMDL): the sum of (1) a waste load allocation (WLA), or that portion of a surface water’s loading capacity that is allocated to an existing or future point source discharge; (2) a load allocation (LA), or that portion of the surface water’s loading capacity that is due to either existing or future nonpoint source pollution or to natural background sources; and (3) a margin of safety (MS), or that portion of a surface water’s loading capacity that is allocated to uncertainty.  See Clean Water Act.

township: federally mandated division of land encompassing 36 square mi and consisting of 36 sections.

tree: Woody plants having one erect perennial stem or trunk at least 3 inches d.b.h., a more or less definitely formed crown of foliage, and a height of at least 13 feet (at maturity).

tributary: a stream feeding a larger stream, river, or lake.

turbidity: a measure of water clarity.

uneven-aged management: timber management method that results in forest stands characterized by trees of many ages or sizes intermingled singly or in groups.

Universal Soil Loss Equation (USLE): an equation developed to predict soil losses due to runoff from specific field areas in specified agricultural cropping and management systems. The equation consists of a rainfall and runoff factor, soil erodibility factor, slope-length factor, slope-steepness factor, cover and management factor, and support practice factor.

upper-stem portion: That part of the main stem or fork of sawtimber trees above the saw-log top to minimum top diameter 4.0 inches outside bark or to the point where the main stem or fork breaks into limbs.

urban and other areas: Areas developed for residential, industrial, or recreational purposes, school yards, cemeteries, roads, railroads, airports, beaches, powerlines and other rights-of-way, or other nonforest land not included in any other specified land use class.

value added: the sum of all income deriving from an industry, including wage income and owner income, less business taxes.

values: relatively firmly held and socially shared positions or expressions about what is good or right; they are abstract and normative and are considered to be somewhat stable.

volume of live trees: The cubic-foot volume of sound wood in live trees at least 5.0 inches d.b.h. from a 1-foot stump to a minimum 4.0-inch top d.o.b. of the central stem.

water quality standard: a standard that defines the goals for a water body or portion of a water body, by designating the beneficial use or uses to be made of the water and by setting criteria necessary to protect the uses. Water quality standards should provide for the protection and propagation of fish, shellfish, and wildlife and for recreation in and on the water, and should take into consideration the use and value of public water supplies. Such standards establish water quality goals for a specific water body and serve as the regulatory basis for the establishment of water quality-based treatment controls and strategies beyond the technology-based treatment required by sections 301(b) and 306 of the CWA.

watershed: the area of land above a given point on a stream that contributes water to the volume of a body of surface water; also referred to as a drainage basin.

wetlands: those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions (U.S. ACE 1987). Wetlands generally include swamps, marshes, bogs, and similar areas; (2) lands that are transitional between terrestrial and aquatic systems where the water table is usually at or near the surface of the land and is covered by shallow water. For purposes of this classification, wetlands must have one or more of the following attributes: (1) at least periodically, the land predominantly supports hydrophytes (plants dependent on saturated soils or a water medium); (2) the substrate is predominantly undrained hydric soil; and (3) the substrate is nonsoil and is saturated with water or covered by shallow water at some time during the growing season of each year.

wild rivers: rivers or segments of rivers included in the NWSRS (P.L. 542-82 stat. 906, as amended) that are free of impoundments; are generally inaccessible except by trail; and the watersheds and shorelines of which are essentially primitive and unpolluted.

wilderness: a Congressionally-designated area that provides opportunities for solitude and primitive, unconfined recreational experiences. There are no constructed facilities such as campgrounds, picnic areas, or interpretive sites and motorized and mechanized vehicles are prohibited.

wildfire: any fire that is not burning for a prescribed management purpose or being managed as a prescribed fire.

woodland range: forest land (within range allotments) that produces minor amounts of forage. It includes occasional even-aged timber harvest areas that have higher forage value for several years before being replaced by shrubs and trees.

woodland: Forest land incapable of producing 20 cubic feet per acre per year of industrial wood under natural   conditions, because of adverse site conditions. 

southern red oak leaf as bottom graphic


webmaster: John M. Pye

created: 25-NOV-2001
modified: 6-JUN-2003