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Non-living parts of the environment, e.g., air, water, coal, geological structures, temperature, topography

Abundance, Index of Relative
Any expression of relative abundance, e.g., a useful approximation of the total number of individuals of a species relative to time or space.
Abundance, Relative
The frequency of encountering an organism in a given time and place relative to the frequency of encounter in another time or place. Typically the smaller divided by the larger number, thus a proportion.
Abundance, Species
An estimate of the total number of individuals of a species in a defined area, population, or community. (Confusion between abundance and density can be avoided if density is viewed as abundance per unit of area or volume).
AC - Assistance Center
A network of offices in the United States and Puerto Rico which serves as information centers for the National Water Data Exchange (NAWDEX). Most of these centers have computerized access to the NAWDEX databases, as well as those of their own agencies.
Permission or legal authority to enter an area; entry points or means (e.g., bridges or fords); the mode of travel available within an area. Access into roadless areas is typically provided for hikers, horseback riders, and, in some cases, mountain bikers. Access with motorized vehicles is not provided or allowed in roadless areas.
Adjustment to environmental change by an individual. The physiological adjustment or increased tolerance shown by an individual organism to environmental change. See Adaptation.
Acid Deposition
Precipitation and dry particulate fallout with low pH linked to other components of air pollution.
Acid Soil
Soil with a low pH, less than 7.0 but practically less than 6.6
43560 square feet of area or 10 units of land 66 feet x 66 feet (a chain is 66 feet)
Acres, Marginal
A component of the regulated commercial forest-land area that includes areas not qualifying as standard or special components primarily because of excessive development costs, low product values, resource protection constraints, and inadequate markets.
Acres, Special
A component of the regulated commercial forestland area that needs special timber management techniques to achieve landscape objectives. Included are peripheral portions of developed recreation sites, and viewscapes where retention or partial retention of the characteristic landscape is a management objective.
Acres, Standard
Areas where crops of industrial wood can be grown and harvested with adequate protection of forest resources, under the usual provisions of a timber sale contract.
A measure, course of action, or treatment that is undertaken to directly or indirectly produce directly or indirectly, produce, enhance, or maintain forest and rangeland and related rural land outputs or achieve administrative or environmental quality objectives.
Activity Fuels
Fuels which have been directly generated or altered by management action. More commonly called slash.
The ability to alter structure or function in response to changes in the environment in such a way that fundamental life processes can continue to cope with (or continue to function in) an uncertain environment.
Capable of undergoing inheritable (and/or non-heritable) structural or functional changes in response to environmental changes that could otherwise impair life processes.
The result of the process of (1) long-term evolutionary adjustment of a population to environmental changes, or (2) short-term physiological/behavioral responses compensating for environmental changes. Frequently a short-term behavioral or physiological response, if it is generally adaptive, will be reinforced by genetic adaptation that ensures the longevity of the short-term response.
Adaptive Management
An approach to natural resource management wherein actions are designed and executed to achieve objectives, but also effects are monitored for the purpose of learning and adjusting future management actions, thereby improving the efficiency and responsiveness of management.
Sexually mature; an animal that has contributed new individuals to a population.
Advance Reproduction/ Advance Regeneration
True seedlings or sprouts of the tree species that occupy the overstory existing as part of the understory vegetation. The root systems of sprout advance reproduction are usually older than the stems, are relatively large, and are capable of supporting much greater stem growth than the root stems of true seedlings.
Adventitious Bud
A bud from a tree bole or stem usually resulting from a branch being broken or the bole being exposed to sunlight
Adverse Impact
An effect that causes harmful interference (beyond limits of acceptable change) with the structure or functioning of a person, place, ecosystem, or object.
Relating to or dealing with perceptions of beauty; the philosophy dealing with beauty and with judgments or perception of beauty; also esthetic.
Artificially establishing forest crops by planting or sowing on land that has not previously, or not recently, grown tree crops; also Reforestation.
Age, Average
The arithmetic mean age of a population or group.
Age Class
A general term applied to organisms which are born, hatched, etc. within a specified time period; also a life stage. Age class time frame varies with generation time of organisms. For example, the young, juvenile, and adult age classes of many small mammals occur within a single year, whereas for trees, the young age class encompasses several years, typically 10. Age intervals into which wildlife or timber stands are divided are commonly 10 years. Age classes are "balanced" when the whole forest has an approximate equal number of acres in each 10-year class from age zero through rotation age.
Age Composition
1. An array of age classes. 2. The arrangement of age classes in a population which describes the relative strengths of the age classes. Synonymous with age structure.
Age Distribution (Age Class Distribution)
Individuals of a population classified according to age classes or periods such as pre-reproductive or sub-adult, reproductive, and post-reproductive. An age pyramid is a diagram of the proportions within each age class of a population.
Age Ratio
Proportion of young to adults, suggesting a measure of productivity.
AgriTourism or Agricultural Tourism
The act of visiting a working farm or any agricultural, horticultural, or agribusiness operation for the purpose of enjoyment, education, or active involvement in the activities of the farm or operation.Agricultural tourism allows farm operators to increase income through a variety of service initiatives such as farm demonstrations, harvest festivals, farm vacations, school group tours, hay rides, pick-your-own crop harvests, bed and breakfasts, campgrounds, crop mazes, and a host of other products and services. These services can be tailored to specific seasons in order to complement farm production. (From Lobo, R. 2000. Helpful agricultural tourism definitions. University of California Small Farm Center, Cooperative Extension.
Air Quality. Class I, II, or III
Designation given to geographic areas of the country where air quality is better than the national standards. Allowable increases (increments) in pollutants are specified for each class. Class I allows the least increase; class III, the most. All National Forest System lands are class II areas except for the 88 wildernesses Designated class I areas on August 7, 1977. See 42 U.S.C. 7473, for description of the specific increments.
Simple rootless plants growing in water and in soil. Algal blooms may adversely affect water quality.
A set of logical and mathematical operations performed in a specified sequence. A repeatable set of rules for action or decision making.
All-aged Forest (Uneven-aged Forest)
A forest which contains trees of all ages, intermixed.
All-Terrain Vehicle (ATV)
A type of off-highway motorized vehicle. These include vehicles with low-pressure tires, commonly called three-wheelers and four-wheelers. Because all-terrain vehicles cannot be licensed or registered under state vehicle laws, they may not be allowed on federal and certain other types of roads.
Allowable Annual Harvest
The volume of timber or timber acreage that may be harvested from an area on a perpetual basis.
Allowable Cut
The amount of forest wood (or forest products) that may be harvested annually or periodically from a specified area over a stated period in accordance with the objectives of management.
Allowable Sale Quantity (ASQ)
The quantity of timber that may be sold from the area of suitable land covered by a plan for a period specified by the plan. This quantity is usually expressed on an annual basis as the average annual allowable sale quantity.
Material such as earth, sand, gravel, or other rock or mineral materials transported and laid down by flowing water. See Colluvium.
Alluvial Fan
A fan-shaped deposit of soil and rock formed by a stream where the velocity is abruptly decreased, as at the mouth of a ravine or at the foot of a mountain.
Alpha Diversity
Any of a variety of definitions of diversity relating to lists of species, abundance of each, and proportional abundance within a community. It is an expression of populations co-occurring at a specific time and space.
Alphanumeric Character
Any numeric digit (a number from 0 to 9), any letter of the alphabet from A to Z, or any special symbol, such as a plus sign (+) or a percent sign (%).
Propositions or situations, a set of actions, usually from among thousands, only one of which may be chosen as describing actions to arrive at a desired future condition. One of several policies, plans, or projects proposed for selection by decision-makers.
Animals which, after birth or hatching, delay attaining a condition of self maintenance.
Amplitude, Ecological
The range of one or more environmental conditions in which an organism or a process can function. See Tolerance.
Analysis of the Management Situation - A step in the planning process (1) to determine the capability of the area to provide goods, services, and uses; (2) to determine whether alternatives to the current direction need to be considered; and (3) to provide basic assessment information for other offices.
The reduction or removal of the pain sense without loss of conciousness following drug administration. Narcosis is a condition of analgesia accompanied by deep sleep or stupor.
Analysis Area
A delineated area of land subject to analyses of (1) responses to proposed management practices in producing, enhancing, or maintaining forest and rangeland outputs and environmental quality objectives, and (2) economic and social impacts.
Ancestor Data Record
A data record at a next higher level within the same data family.
Angle of Repose
The maximum angle (or percent slope) to the horizontal at which any soil or loose or fragmented solid material will stand without sliding, e.g., soil on a roadside cut.
Angle of Slide
The slope, measured in degrees of deviation from the horizontal, on which loose or fragmented materials will start to slide, slightly greater than the angle of repose.
Animal Community
The characteristic assemblage of animals associated with a forest type or ecological community.
Animal Month
Tenure during 30 days upon range by one animal.
Animal Unit
A measure for converting types of animals to forage resources. It is based on the equivalent of the forage required by a mature cow of about 1000 pounds.
Animal Unit Conversion Factor
A numerical grazing measurement figure which allows conversion from one kind or class of animal to another (e.g., equivalent animal months). Such a conversion factor expresses the amount of forage required to maintain an animal. It may have no application in determining stocking rates for range use for particular animals. Conversion factors generally accepted are: mature cow with calf, 1.0; mature bull, 1.25, weaned calf, 0.6; yearling over 12 months and under 17 months, 0.7; yearling from 17 to 22 months, 0.75; two-year old from 22 to 32 months, 0.9; elk, 0.7; white-tail deer, 0.14; mule deer, 0.2; mature ewe with lamb, 0.2; ram, 0.2; weaned wether, 0.17; doe goat with kid, 0.17; buck, 0.17; weaned wether, 0.14 and grown horse, 1.25.
Animal Unit Month (AUM)
The quantity of forage required by one mature cow (1000 lbs) or the equivalent for 30 days.
Animal, Wild
(1) Animals, or their progeny, which once were domesticated but escaped captivity and are running wild (i.e., feral animals). Horses, burros, and hogs are not considered to be wildlife. (2) Undomesticated vertebrate animals except fish, considered collectively. (3) Generally, all non-domesticated non-plant life including microscopic forms, insects, crustaceans, mollusks, and fish. (4) More particularly, a loose term that includes non-domesticated vertebrates, especially mammals, birds, and fish, and some of the higher invertebrates (such as crabs, crayfish, etc.). (5) Living things that are neither plant, human, nor domesticated; especially the mammals, birds, and fishes that are hunted by people for sport or food.
Plants that normally live less that one year.
The combined actions of two or more agents, the result of which is less than the sum of the actions of each of the agents acting separately or independently. Antagonism may be "results" or merely the net "actions" themselves. See Synergism.
Antecedent Moisture (Antecedent Soil Water)
The degree of wetness of the soil at the beginning of a runoff period expressed as an index or as the total inch-depth-equivalents of water stored in the soil.
Antiquities Act (34 Stat. 225)
The Antiquities Act of 1906 provides for protecting historic and prehistoric remains, or any antiquity object, on Federal lands; establishes criminal sanctions for unauthorized destruction or appropriation of antiquities and authorizes scientific investigation of antiquities on Federal lands, subject to permit and regulations.
A disease characterized by ulcer-like leaf or fruit spots and caused by fungi that produce asexual sspores in the type of fruiting body called a acervulus.
Pertaining to standing and running water in streams, rivers, lakes, ponds, and reservoirs.
A geologic formation, group of formations, or part of a formation that contains sufficient saturated permeable material to hold and yield significant quantities of water to wells and springs. If a well taps more than one aquifer, the principal aquifer will be the one that yields the greatest amount of water. In aquifers, water moves more readily than in adjacent formations with lower permeability. The term "water-bearing" is sometimes used synonymously with "aquifer" when a stratum furnishes water for a specific use. Aquifers are usually natural sands, gravel, and fractured or porous rock.
Archeological Area
Sites and areas which have been Designated as containing important evidence and remains of the life of people on Earth between the time of their first appearance and the development of written history. Archeological remains are the sole kind of evidence that applies to pre-history and they may provide information about all aspects of human life.
Archeological Resource
All remaining physical evidence of former occupation by now-extinct cultural groups. Evidence includes skeletons, settlement remains, implements, artifacts, monuments, and inscriptions. In the U.S. this subclass is distinguished from its more recent counterpart "historical resources" by a point in time between it an movement of settlers into an area. This resource class does not include any of the more recent physical products of contemporary native cultural groups such as may exist on Indian reservations.
Area of Analysis
The geographic area within which ecosystems, their components, or their processes are evaluated during analysis for one or more plans, plan revisions, or plan amendments. This area may vary in size depending on the relevant planning issue. An area of analysis may be larger than a plan area. An area of analysis may include multiple ownerships
Area Mining
Surface mining that is carried on in level to gently rolling topography on relatively large tracts.
Area of Critical Environmental Concern (Critical Area)
A phrase used in the defeated 1973 bill for a National Land Use Policy and Planning Assistance Act. Areas, as defined and Designated by states on non-Federal lands, where uncontrolled or incompatible development could result in significant damage to the environment, life or property, or the long term public interest which is of more than local significance. Three specific classes of critical areas were defined in the Act -- fragile or historic lands, natural hazard lands, and renewable resource lands. States could add additional types of areas of critical concern. Coastal areas were specifically deleted from the definitions of the types of areas of critical environmental concern. In an amendment relating the Coastal Zone Management Act to this Act, the words "coastal wetlands, marshes, and other lands inundated by the tides, beaches, dunes and significant estuaries" were deleted from the definition of fragile or historic lands. A state is free to add these areas to its state land use program. However, the state need not do so, but rather it can keep such areas separate and accountable only to the requirements of the Coastal Zone Management Act. The Land Use Policy and Planning Assistance Act did not require the Federal government to Designate such areas on Federal land. Areas of critical environmental concern were to be Designated only on private, state, and Indian lands. These definitions were purposely left legally incomplete, in accordance with the purpose of the Act, to improve the states' ability to devise and implement their own land use policies. By further refining these definitions, the states make the first basic policy decisions concerning the scope and the thrust of the state land use programs. For example, major policy decisions are involved in determining what is a "shoreline". Is it a shoreline of all bodies of water or only bodies of a certain size? Is it limited to relatively undeveloped shoreline? Is its extent 400 feet inland of the water, 400 yards, or to the extent of any land the use of which has a direct impact on the water? What are "major recreational lands and facilities"? What are "issues of more than local significance" in the judgment of the state? This category is not designed to be a "no growth" category. Only uncontrolled development is unwanted. The adjective "incompatible" is present to make certain that development is to be allowed which is compatible with the basic environmental or renewable resources values or safety problems of the land in question. Multiple use, when planned, is clearly expected. The category "Areas of Critical Environmental Concern" has been subdivided into categories to pinpoint the basic values of land so as better to provide opportunities for development which can demonstrate the compatibility of areas with such values.
Area, Geologic
Areas containing scientifically or educationally significant fossilized specimens of flora and fauna from previous geologic periods e.g., coal swamp forests, dinosaurs, etc. Vertebrate fossils of historic or scientific significance are included as "antiquities" within the Antiquities Act.
Area Reconnaissance
Early visits to observe an area and its ecological, economic, and social conditions and to determine the scale and scope of plans and subsequent work (or visits and information collection.)
Arterial Roads
Roads and trails that provide service to large land areas and that usually connect with public highways or other forest arterial roads to form an integrated network of primary travel routes. Their location and standard are often determined by a demand for maximum mobility and travel efficiency rather than specific resource management service. Such roads are usually developed and operated for long-term land and resource management purposes and constant service.
Invertebrate animals with jointed legs and a segmented body such as insects, mites, and spiders.
Artificial Feeding
Artificial feeding of wild animal life means placing food into the environment that supplements the food sources contained naturally within in the home range of a wild species. Usually directed at populations of animals, it may apply to feeding individual animals.
Artificial Regeneration or Reproduction
Planting or seeding to establish a new crop of trees on an area, usually timber has been removed.
Aspect (Exposure)
The compass direction in degrees azimuth toward which a land slope faces (the direction downhill). Since plants suffer their greatest moisture losses through evapotranspiration on southwest facing slopes (which receive the greatest energy input from the sun compared to that received by other slopes), aspect can be an important factor influencing vegetation distribution. Giles (in 1999) recommended separating and studying the influences of north-south aspects (primarily solar influences) and east-west aspects (primarily coastal, anthropogenic, wind and rain influences)
Results of analyzing and interpreting the existing social, economic, or ecological characteristics or conditions of an area using scientific principles (e.g., as they may affect "sustainability").
Anabolism or constructive metabolism; the process of taking in and converting nutrient substances into components of living tissues; the conversion of non-living matter into protoplasm.
(1) A commonly-occurring relationship between two or more species which can be readily recognized in the field and treated as an ecological unit; (2) An actual or concrete community, stand, or group of organisms characterized by a definite floristic composition, presenting uniformity in physiognomy and structure, and growing under uniform habitat conditions; (3) A group of things classified together because they meet certain standards of similarity; (4) A climatic climax unit that includes all of the successional stages preceding or associated with it. Plant associations and animal associations emphasize populations of plants or animals respectively within an area.
Association, Index of
A measure of the probable occurrence together of one species with another.
A judgmental decision by planners which supplies missing values, relationships, or societal preferences for some informational component necessary for making a decision. The true nature of such missing information is either unknown or cannot be readily ascertained within the time and/or budgetary constraints on a decision.
A learned predisposition, feeling, or conviction manifesting itself in a general state of readiness either to evaluate or to react toward an object or class of objects in either a favorable or unfavorable manner in a more or less consistent and characteristic way. Attitudes are relatively stable and have three components: a cognitive or belief component, an affective or feeling component, and a connotative or action-disposition component. Although behavior may be a function of attitude at times, attitudes are not necessarily predictors of behavior. Consequently, changes in attitudes do not always result in changes in behavior.
A characteristic of a component. The sum of knowledge of all attributes defines a component, e.g., attributes of grass include color, phenology, live biomass, dead biomass, litter biomass, etc.
Auger Mining
Generally practiced but not restricted to hilly coal-bearing regions of the country. Utilizes a machine designed on the principle of the storage pile or bin for loading and transporting. May be used alone or in combination with conventional surface mining. When used alone, a single cut is made sufficient to expose the coal seam and to provide operating space for the machine. When used in combination with surface mining, the last cut pit provides the operating space.
See Animal Unit Month.
Autotrophic Organism
An organism capable of synthesizing organic matter from inorganic substances. In contrast, a heterotrophic organism must have organic matter as its source of food.
Average Daily Traffic (ADT)
The average 24-hour volume of traffic, being the total volume of traffic during a stated period divided by the number of days in that period. Unless otherwise stated, the period is 1 year.
Compass direction from a point, measured in degrees clockwise from true North.

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Last revision January 17, 2000.