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T Factor (Soil erosion related usage)
See Soil Loss Tolerance.
A violation of the U.S. Constitutional provision " . . . nor shall private property be taken for public use without just compensation ... ." by a system of land use regulation. Although the Fifth Amendment's prohibition of "takings" of property without "just compensation" applied to the states by virtue of the Fourteenth Amendment (Chicago, B. and O. Rr. vs. Chicago, 166 U.S. 226 (1897)), it has long been established that state regulation based on the police power may substantially diminish the economic value of private property without giving rise to an obligation to compensate the owner. See e.g., Mugler vs. Kansas, 123 U.S. 623 (1887); Euclid vs. Ambler Realty Co., 272 U.S. 365 (1926). There is a very hazy boundary between "taking" (compensation required) and "police power" regulation (compensation not required). The Supreme Court itself has acknowledged that "there is no set formula to determine where regulation ends and taking begins" (Goldblatt vs. Hempstead, 369 U.S. 590, 594 (1962)). In the language of the decided cases, the phrase "police power" normally connotes that the action in question is being taken without compensation to the property owner. By contrast, where compensation for a "taking" is contemplated, the cases speak of "eminent domain" or "expropriation" powers. Most of the Supreme Court cases in this area have involved zoning laws or other governmental action largely unrelated to environmental concerns. Taking (continued) - See, e.g., United States vs. Causby, 328 U.S. 256 (1946). However, in recent years, several state court decisions have invalidated, under the Federal or state constitutions, state or local police power (no compensation) initiatives designed primarily to preserve the natural environment. See, e.g., Bartlett vs. Zoning Commission, 232 A. 2D 907 (Conn. 1971); Maine vs. Johnson, 265 A. 2D 711 (ME 1970); Dooley vs. Town Plan and Zoning Commission, 197 A. 2D 770 (Conn. 1964). From U.S. Dep. Justice comments in U.S. Congr., Senate Com. Inter. Insular Aff. 1973) Taking is an issue in planning centering around the right of the government to control private use of private land, in effect taking away property rights for the common good. It involves purchasing lands through eminent domain for special purposes, compensation for decreased property values due to regulation, and the rights of private owner ship versus public needs.
A system of recording trees counted during a timber cruise.
The main root of a tree which strikes downward with or without heavy branching until it either reaches an impenetrable layer or one so lacking in oxygen or moisture that further downward growth is impossible.
A clear and concise statement used to express planned results to be reached within a stated time period. Often one or more separate targets are used. These are system performance measures.
The science of classifying organisms; the arrangement of organisms into systematic groups such as species, genus, family, and order. It is the theoretical study of classification including its bases, principles, procedures, and rules.
Technological Assessment (Technological Forecasting)
The attempt to estimate or predict the completely new technological developments which will occur in the future; and, to evaluate the extent to which such likely, future new abilities will be able to solve (or at least acceptably minimize) current land use problems, or problems which are expected to be associated with particular land uses in the future.
Technological Change
The increase in society's ability to solve problems or increase efficiency by technical means with time. Availability of alternative or completely new technical methods for solving problems associated with land uses and the inevitable evolution and development of new ideas.
Technological Solution
The application of the devices or techniques developed by science for practical purposes. Often these are completely new technical methods for solving current or potential problems for which no "technological solutions" presently exist. The distinction between "technical solutions" and "engineering solutions" is that the first refers just to the development of new technical means while the last applies to the application of any technical means (new or old) to solving potential problems.
Automatic transmittal of data to a point remote from the sensing instrument. Also use of small radios to monitor animal location, movement, behavior, and physiology.
A measure of the intensity of heat energy present.
Temporary Facility (Road)
A temporary use of the land for transportation purposes; usually constructed to serve a specific resource activity. Occupied land is returned to resource production upon termination of the activity requiring its use.
Temporary Permit (Temporary License)
A document authorizing grazing a certain number of livestock on public lands during an emergency or for a certain period, terminable at the end of such period and with no guarantee of renewal in whole or in part.
Term Permit (Term License)
A document that authorizes grazing on public lands for a stated number of years as contrasted with an annual or temporary permit.
Terminal Facilities
Parts of the transportation network and interface between the transportation network and resources served or between different transportation modes, e.g., vehicle parking areas, boat ramps and docks, trail heads, log landings and dumps, and air fields and heliports.
A level plain bordering a stream, river, or lake.
Terrace, Asorptite
A ridge type of terrace used primarily for moisture conservation.
Terrace, Bench
A terrace approximately on the contour, having a steep or vertical drop to the slope below, and having a horizontal or gentle sloping part.
Terrace, Drainage
A broad channel-type terrace used primarily to conduct water from an area at a low velocity. It is adapted to less absorptive soil and high rainfall.
Terrace Threshold Sensitivity Level
Sloping ground cut into a succession of benches and steep inclines for purposes of cultivation or to control surface runoff and to minimize soil erosion.
A tract of country considered with regard to its natural features, configuration, etc.; especially as affecting its advantages, fitness for use.
Terrain Analysis
The process of interpreting a geographical area to determine the effect of the natural and human-made features on a particular activity, actual or proposed. This interpretation includes the influence of weather and climate on those features.
Terrain Factor
Terrain factors are attributes or land forms, drainage features, ground, vegetation, etc. and cultural features or human-made changes in the Earth's surface.
Terrain Studies
Regional studies usually with an emphasis on relief and essential physical features, e.g., soil, vegetation, and drainage.
The area which an animal defends, usually during breeding season, against intruders of its own species. Territories are smaller than and are normally located within an animal's home range.
The behavior by which an organism claims an area and displays, threatens, and defends it against members of its own species.
Tertiary Facility
Tertiary transportation facilities are usually intended to provide access for a specific resource utilization activity, such as a timber sale or recreation site, although other minor uses may be served. Emphasis is given to resource service rather than travel efficiency. Tertiary facilities may often be developed and operated for short term or intermittent service.
Tertiary Wastewater Treatment (Tertiary Treatment, Tertiary Sewage Treatment)
Wastewater treatment processes, beyond primary and secondary treatment, which remove or reduce the amount of nitrate and phosphate nutrients present in their effluents. Tertiary treatment may consist of extensions or modifications of secondary treatment processes, additional forms of chemical treatment, electrochemical processing, carbon filtration, and other more complex procedures. Tertiary treatment removes up to 99 percent of the suspended solids and biological oxygen demand, 95 percent of the phosphate and 75 percent of the nitrate from wastewater.
Thermal Cover, Structural
For big game (elk) a stand of coniferous trees 40 feet tall or taller with average crown closure of 70 percent or more. In some cases, topography or vegetation less than specified may meet animal needs for thermal regulation. Functional: Situations, usually related to vegetation structure, used by animals to ameliorate effects of weather.
Thermal Enrichment
See Thermal Polution.
Thermal Pollution (Thermal Enrichment, Calefaction)
Altering the amount of energy available in the environment by adding heat or cold. Most frequently this occurs in the form of the heat added by returning water which has been used for cooling purposes to a river, lake, estuary, bay or the ocean. However "thermal pollution" may also occur with the release of large volumes of the cold, deep water in reservoirs into warmer bodies of water.
The layer of water in a lake between the epilimnion and hypo-limnion in which the temperature exhibits the greatest difference in Minimum level of exposure to a specific pollutant which results in a detectable effect. The important factor is to differentiate between visible and non-visible (physio-logical-internal) effects.
Cutting made in an immature crop or stand in order to accelerate the diameter increment (annual growth) of the residual trees but also, by suitable selection, to improve the average form of the trees that remain, without (at least according to classical concepts) permanently breaking the canopy. Commonly expressed as " a basal area per acre of X amount for all trees over 5 inches in diameter."
Soil liquefaction
Threatened and Endangered Species
A species or subspecies of animals or plants whose prospects of survival and reproduction are in immediate jeopardy (endangered), or likely to become so within the foreseeable future (threatened). The Secretary of Interior identifies threatened species in accordance with the 1973 and subsequent Endangered Species Acts.
Threatened Species
Any species that is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range and that has been Designated in the Federal Register by the Secretary of the Interior as a threatened species.
Threshold Level
The minimum concentration or amount of a given substance or condition necessary to produce a measurable physiological or psychological effect. Also, the point at which a major change occurs, e.g., the change of water to ice at zero degrees centigrade.
Tiel Gradient
The temperature difference within a layer 1 meter thick.
Incorporating information contained in an Environmental Impact Statement (EIS), such as the Forest Plan EIS, by reference in subsequent environmental documents.
The physical condition of a soil in respect to its fitness for the growth of a specified plant.
Standing trees, usually of commercial size.
Timber Harvest
The removal of trees for wood fiber utilization and , in the US Forests Service and some other places, other multiple use purposes
Timber Inventory
A collection of information about a timber stand made by measuring tree and stand characteristics such as tree volume and grade and stand density.
Timber Management Compartment
A small subdivision of forest area for purposes of orientation, administration, and silvicultural operations, and defined by permanent boundaries (either of natural features or artificially marked) which are not necessarily coincident with stand boundaries.
Timber Production
  1. Purposefully growing, tending, harvesting, and regenerating of regulated crops of trees to be cut into logs, bolts, or other round sections for industrial or consumer use. The term does not include production of fuelwood or chip products.
  2. The sustained long-term and periodic harvest of wood fiber from National Forest System lands undertaken in support of social and economic objectives identified in one or more land and resource management plans. For purposes of this rule, the term timber production includes fuel wood.(USFS 1999)(and 36 CFR 219.16)
Timber Resource System
The role of a timber resource system is to grow and make available wood for the nation on a continuing basis. Thus, the system includes those activities necessary to (1) protect, improve, grow, and harvest timber from forest land and (2) protect, process, and utilize wood and wood-related products. In addition to wood, the system produces other goods and services, either by design or incidentally.
Timber Sale
Issuance of a contract for cutting and removing Designated trees; the site and or work being done under such a contract.
Timber Sale Program Quantity
The volume of timber planned for sale during the first decade of the planning horizon. It includes the allowable sale quantity (chargeable volume) and any additional material (non-chargeable volume) planned for sale. The timber sale program quantity is usually expressed as an annual average for the first decade.
Timber Site Index
A measure of site productivity based on tree height growth over 50 years.
Timber Stand
A community of trees sufficiently uniform in composition of species, size, age, etc. to be distinguished from adjacent communities. Maximum and minimum sizes are usually established to provide for other resource coordination or practicable timber management.
Timber Stand Improvement (TSI)
All noncommercial intermediate cuttings (i.e., removing less desirable trees, vines and, occasionally large shrubs) and other practices to improve the composition, constitution, condition, stocking, and increment of a residual forest stand.
Timber Type
See Cover Type.
Time of Travel
The rate of movement of water, or waterborne materials, through a defined reach of stream channel for steady or gradually varied flow conditions. Determined by dye tracing methods where dye is injected at some location on a stream and detected at other locations downstream (any time-distance measure).
Time Zoning
See Zoning, Time.
See Median Tolerance Limit.
Texas Natural Resources Information System. Established to serve as a mechanism for linking together the users of natural resources and related data with those agencies and institutions that collect and store such data in the State of Texas. Development and operation of TNRIS is guided by a Task Force made up of representatives from 15 State agencies having responsibilities in the area of natural resources and related data.
Tolerable Soil Loss
The amount of soil that can be lost over 100 years from accelerated erosion and not significantly or permanently lower soil productivity potential.
(1)Resistance of an organism to high levels or excesses of a substance or the deficiency of an element or a condition in its environment e.g., elm trees are "resistant" to periodic flooding.(2)The capacity of a tree to develop and grow in the shade of and in competition with other trees. Trees able grow in full or partial shade are considered "tolerant." Trees requiring full sunlight for survival are considered "intolerant. "
Tolerance, Ecological
(1) The positive response of an organism to the excess or the deficiency of an element or a condition in its environment. (2) The capacity of an organism to endure or adapt to (usually temporary) unfavorable environmental factors. (3) An organism's capability to withstand a condition indefinitely and through all life stages. Short-term "tolerance" should be redefined in terms of stress.
Tolerance Limit, Median
The concentration of some toxic substance at which just 50% of test animals are able to survive for a specified period of exposure.
The configuration and relations of a surface including its relief, elevation and the position of its natural and human-made features. The physical or natural features of an object or entity and their structural relationships.
Earthy material used as top-dressing for house lots, grounds for large buildings, gardens, road cuts, or similar areas. It has favorable characteristics for production of desired kinds of vegetation or can be made favorable. Also the surface plow layer of a soil. The original or present dark colored upper soil that ranges from a mere fraction of an inch to two or three feet thick on different kinds of soil. The original "A" soil layer varying widely among different kinds of soil. Applied to soils in the field, the term has no precise meaning unless defined as to depth or productivity in relation to a specific kind of soil. Fertile soil material that is used as a top dressing. Distinction has been made among synthetic, weathered, and geologic topsoil. Synthetic topsoil can include sand and stone chips as well as fly ash, sawdust, or manure not usually a part of geological soil and rock. Weathered topsoil is the natural top-dressing material that has been subjected to all ecological processes through a long period.
A substance or the excessive amount of a substance that may cause death, stress, or impairment. Characteristics of things called poisons or toxins.
Toxicity, Acute
(1) Inhibition after an infinitely short exposure to a toxicant. (Berry) (2) Toxicity which causes severe and rapid damage to the organism by the fastest acting mechanism of poisoning, fatal unless the organ-ism rapidly escapes the toxic environment.
Toxicity, Chronic
Inhibition which may be lethal or sub-lethal after a long-term (relative to life cycle) exposure to a toxicant.
Toxicity, Lethal
Concentration at which a toxicant causes death. (1) Concentration at which a toxicant first causes inhibition. (2) The lowest concentration (of a toxicant) that causes acute tox-icity.
Toxicity Test
A test that determines the potency of a toxic substance by measuring the intensity of a biological response.
Toxicity, Unit
Inhibition per log unit of toxicant at concentration greater than threshold toxicity.
Trace Elements
Chemical elements appearing in minute quantities in natural systems or media; may occasionally be concentrated by specific organ-isms. Nutrients such as P, though in minute quantities, are not usually called trace elements.
Trace Elements, Essential - Toxic Effects
A reduction in crop or ecosystem yield below that of the maximum yield plateau of a complete dose response curve and at concentrations greater than those required for maximum yield.
Trace Elements, Non-essential - Toxic Effects
A reduction in yield below that of the zero dose level.
Tractor Logging
See Logging, Tractor.
The combination of benefits and costs which are gained and lost in switching between alternative courses of action. "Trade-offs" include only those portions of benefits and costs that are not common to all alternative courses of action under consideration. The total estimated amount of resource program outputs (market and nonmarket) foregone by (1) modifying an existing program or substituting one resource program for another or (2) due to switching among alternative courses of action. The economic value of this trade-off represents the Opportunity Cost.
Traffic Classification
See Traffic Composition.
Traffic Composition (Traffic Classification)
The classification and grouping of the various sizes and weights of vehicles making up the traffic of a road such as passenger cars and trucks.
Traffic Service Levels
Traffic service levels describe the significant traffic characteristics and operating conditions for a road.
Traffic Volume
The number of vehicles traveling in both directions past a given point during a specified period of time. This is usually expressed as seasonal average daily traffic for roads that are open only part of the year, or annual aver age daily traffic for roads (highways) open year round.
An 18-inch to 24-inch wide travel-way designed for pedestrian and/or horse riders. Also includes a travel-way up to 40 inches in width to accommodate off-road vehicles.
Damage to plants or soil brought about by foot movements or congestion of livestock and/or people.
Transportation and Utility Corridor
A parcel of land, without fixed limits or boundaries, which is being used as the location for one or more transportation or utility rights-of-way.
Trasaction Costs
The costs of bargaining, negotiating, and exchanging. These rise (time and difficulty) as more people with greater diversity become involved in decision making. Costs include those of identifying, locating, and contacting participants (See R. Coase , 1960, The problem of social costs, J. Law and Economics)
Transitional Range
Areas where big game concentrate during spring and/or fall. Transitional ranges are generally adjacent to winter range and may provide important security during the fall.
Transitory Range
Rangeland created to increase forage production for livestock.
Transmission Pipeline
A pipeline which carries gas or liquid from a producing field or central collection facility to a storage or consumption facility, usually over long distances.
Transmissivity (Water)
The rate at which water of the prevailing kinematic viscosity is transmitted through a unit width under a unit hydraulic gradient.
The loss of water in vapor form from a plant, mostly through the stomata and lenticels.
A tree which has been removed from its original seedbed and replanted one or more times in a nursery.
Transportation Network
All existing and planned roads, trails, bridges, airfields, and other transport facilities wholly or partly within or adjacent to and serving a planning area.
Transportation Planning
The process by which new transportation facilities (and improvements to the old facilities) are systematically designed, their adequacy tested, and their future construction programmed. Comprehensive transportation planning considers all modes (mass transit, automobile, air, rail, etc.) of transportation and treats them all as a single system.
Transportation Services Land
U.S.NRCS (Soil Conservation Service) usage. Land used primarily for highways, roads, beltways, railroads, utility rights-of-way, airports, and other transportation facilities, together with necessary adjacent facilities such as approaches, underground and surface utilities, and other servicing structures, appurtenances, and measures.
Travel Corridor
An area adjacent to a road or trail which includes all of the land normally visible from the road or trail; a strip of land believed to be frequented by wild fauna.
Travel Influence Zone
Areas comprising existing or anticipated significant public outdoor recreational occupancy, use, and enjoyment along existing and planned overland routes of travel; areas in and around existing or planned developed recreation sites. These are areas in which beauty of the landscape and other aesthetic values are key management considerations and are an important part of the out door environment. These areas offer significant opportunities for existing, planned, or anticipated recreational use and enjoyment by people visiting or traveling through the zone.
A woody plant having a well-defined stem, more or less definitely formed crown and usually attaining a height of at least 10 feet.
Tree Cavities
Hollow cavities in trees that provide resting or nesting places for wildlife.
Tree Farm
A privately owned forest (woodland) dedicated to the production of timber crops. Additionally, it may be recognized as a "Tree Farm" by the Tree Farm Program, an organization sponsored by the American Forest Industries.
Tree Injector
Equipment specially designed to inject chemicals, usually phytocides, into the trunk of a tree.
Tree Shelter
A plastic tube that can be wrapped around the stem of hardwood seedlings to increase survival and growth.
Trim Allowance
Excess length of a log to allow for square trimming the lumber to an exact length.
Trophic Level
In biotic communities organisms the food of which is obtained from the same part of the food chain. Green plants occupy the first trophic level, plant-eaters (i.e., herbivores) the second level, the carnivores (i.e., meat eaters) which eat the herbivores the third level, and secondary carnivores (i.e., carnivores which eat other carnivores) the fourth level.
Trout Stream
A stream that contains natural reproducing or stocked population(s) of any trout species or combination of trout species.
Trust Funds
Funds collected and used by a state or federal government for carrying out specific purposes and programs according to terms of a trust agreemenent or statute. Trust funds are administered by the government in a fiduciary capacity and are not available for the general purposes of the government.
See Timber Stand Improvement.
The capacity of materials suspended in water to cause light to scatter; it is measured in arbitrary Jackson Turbidity units (JTU). Highly turbid water is often called "muddy" although many kinds of suspended particles contribute to turbidity.
A widened space in-a road to adlow vehicles to pass one another and which slopes away (downhill) from the road. Also, a drainage ditch which drains water away from roads.
Type Conversion
The conversion of the dominant vegetation in an area from one species to another.

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Last revision January 17, 2000.