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See Environmental Assessment.
An interest or legal right in the land of another person that allows the easement holder to engage in specified uses or rights without actually owning the land. The person or estate against which the easement or privilege exists is called the servient tenement and the estate to which it is annexed is the dominant tenement and their owners are called respectively servient and dominant owner.
Easement, Conservation
A group of negative and affirmative easements that keep land permanently in open use or a natural state, or provide some other conservation or recreation function. These include scenic, flooding, and agricultural easements. Easements may include the following provisions: (1) prohibitions against erecting buildings or other structures; (2) restrictions against constructing or altering any private drives or roads; (3) prohibitions against removing or destroying trees, shrubs, or other greenery; (4) restrictions against uses other than residential or agricultural, for public utilities, and existing uses; (5) restrictions against displaying outdoor signs, billboards, or any other form of outdoor advertising; (6) prohibitions against dumping or storing trash, wastes or unsightly or offensive materials of any kind; (7) other kinds of restrictions consistent with open space preservation and reservation.
Easement, Continuing
An easement which is self-perpetuating, independent of human interventions, as the flow of a stream, or one which may be enjoyed without any act on the part of a person.
Easement, Discontinuous
An easement, the enjoyment of which may be had only by the interference of a person, e.g., a right-of-way or a right to draw water.
Easement, Negative
An interest in land which can give the easement-owner the right to prevent the owner of the land from doing something on it, e.g., scenic easements.
Easement, Recreational
Affirmative easements allowing public entry on the servient (see Dominant) land to hunt, fish, or enjoy other recreational activities.
Easement, Scenic
Essentially an easement of view. Scenic easements restrict the use of land adjacent to public highways, parks, and rivers. They may provide something attractive to look at within the easement area, an open area to look through to see something attractive beyond the easement itself, or a screen to block out an unsightly view beyond the easement area.
A classification system for the biological and earth sciences based on linking together existing disciplinary classifications of the major ecosystem components. It is a unifying framework for linking three basic biological and earth science stratifications or classifications: the vegetation subsystem, the land subsystem, and the aquatic subsystem. A hierarchical structure is given in which the lowest level units are the "ecological land unit" (ELU), a composite of the land and vegetation subsystems, and the "ecological water unit" (EWU), a composite of elements of the land and aquatic subsystems.
Ecological Composition
The biological components of an ecological system, which are the foundation of diversity at the genetic, species, and landscape scales. Genetic diversity is the variation in inheritable characteristics within and among individual organisms and populations. Species diversity is the number and different kinds of species present in a given area. Landscape diversity is the variety of plant communities (including their identity, distribution, zuxtaposition, and seral stage) and habitats evaluated at the landscape scale.
Ecological Conditions
(USFS 2005) Components of the biological and physical environment that can affect diversity of plant and animal communities and the productive capacity of ecological systems. These components could include the abundance and distribution of aquatic and terrestrial habitats, roads and other structural developments, human uses, and invasive, exotic species
Ecological Niche
(Much debated) The role a particular organism plays in the environment.
Ecological Pyramids
Groups of organisms in nature often consist of many small organisms associated with a few larger organisms. This distribution of number and size has been compared to a pyramid with a broad base representative of numerous small organisms and the point of the pyramid representing a few largest organisms.
Ecological Succession
The orderly, likely sequential transition of an area through distinctively different stages of development
Ecological Sustainability
The maintenance or restoration of ecological system composition, structure, and function which are characteristic of a plan area over time and space, including but not limited to ecologicaL processes, biological diversity, and the productive capacity of ecological systems.(USFS 1999)
Ecological Stability (Balance of Nature)
An ecological system may be said to be stable during that period of time when no species becomes extinct (thereby creating a vacant niche) and none reaches plague proportions for long enough to destroy the niches of other species and cause them to be come extinct. A stable ecosystem is one in which all niches are fully occupied by appropriate species. Whatever stability there is in the ecological world it is not a static equilibrium, but a fluctuating or dynamic one, one normally a highly fluctuating. Stability lies in the ability to bounce back, not in the ability to hold tenaciously to ground once taken or numbers once achieved.
Ecological Determinism
A particular point of view in planning which advocates that retaining natural elements and processes should be given priority in planning. Natural elements (such as aquifers, wildlife breeding areas, and flood plains) which are valued by segments of society or that freely perform necessary life support or quality of life functions, or whose alteration will significantly damage other valued resources, should be protected in plans. Ecological determinism is a synonym for physiographic determinism, biological primacy, and biophysical determinism. Although "ecological" strictly implies concern with organisms and their environmental relationships, "ecological determinism" also applies to retaining such nonliving environmental elements as aquifers, steep slopes, and severe storm impact zones.
Ecological Land Type (ELT)
An area of land with a distinct combination of natural, physical, chemical, and biological properties that cause it to respond in a predictable and relatively uniform manner to the application of given management practices. In a relatively undisturbed state and/or at a given stage (sere) of plant succession, a predictable and relatively uniform plant community usually occupies an ELT. Typical size generally is in the mid-hundreds of acres.
Ecological Land Type Phase
These are subdivisions of those ELT's where vegetation management is most common. They share the same characteristics as ELT's; however, their size is smaller (10-100 acres) and the biological and physical conditions are more limited. They are also known as Forest Habitat Types.
Ecological Land Unit (ELU)
One of the lowest levels of the "Ecoclass" system of classifying subdivisions for forest management. Units of land having strong slope steepness; aspect; rock types and conditions, geomorphology, soil characteristics and productive capabilities, type, density and age of vegetation, and drainage character. The basic physical unit of land that scientific disciplines agree must be delineated and examined as a separate entity (for evaluating or management purposes), and analysis of onsite potentials, capabilities and limitations. It is the most significant level of land stratification which best communicates the basic (inherent) capabilities and limitations. These are land (or water) units which, because of their strong uniformity in physical and biological characteristics, respond similarly to management activities or other stimuli. They are sometimes called response units.
Ecological Management Unit (EMU)
A segment of the landscape which contains soils with similar characteristics, enabling it to be managed as a single body. A coded map unit of the Soil Resource Inventory. Each EMU is based on five components - landform, source of materials, texture, water regime, and modifiers, and reflects soil capabilities. The primary component is landform.
Ecological Water Unit (EWU)
The lowest levels of the "Ecoclass" system of classifying divisions for forest description and management. An EWU is a composite of elements from the land and aquatic subsystems, where aquatic type and the adjacent land types together define a homogeneous unit.
(1) A branch of science dealing with the relationships of organisms and their cycles and rhythms, community development, and environments -- especially as manifested by natural structure, interaction between different kinds of organisms, geographic distributions, and population alterations. (2) The study of the relation of organisms or groups of organisms to their environment. (3) The study of the relations among living organisms and their environment. (4) The scientific discipline that is concerned with the relationships between organisms and their past, present, and future environments. These relationships include physiological responses of individuals, structure and dynamics of populations, interactions among species, organization of biological communities, and processing of energy and matter in ecosystems (ESA 2004 annual report)
Testing and quantifying of economic theories and the solution of economic problems by their conversion to mathematical forms, applying mathematical processes, and using statistical techniques.
Economic Analysis
Studying the economic effects of a given action or decision. The effectiveness of various proposed resource management alternatives or combinations of alternatives are studied using the estimation of costs, output volumes, and values for the outputs etc. and how they may also vary each year in an expected pattern of flow in the future. It includes measurement of all pertinent desirable and undesirable consequences to all segments of the economy stated in comparable, monetary terms. Monetary values are discounted to a common time. It may also include an analysis of factors not quantifiable in monetary terms.
Economic Determinism
A point of view which advocates that planning decisions should be based primarily upon the results of analysis of changes in resource supply and demand in response to changes in the "price" for the right to use a resource. That potential user or use which is willing or able to give up the most wins the use rights. Maximizing the total economic welfare is considered to result in maximizing the benefits to society from resource use allocation and this is viewed a being the goal of all resource use. Total economic welfare will be maximized by providing the resources to the highest bidders in such quantities that the price individuals are willing to pay exactly equals the cost of providing the last unit of the resource, under standard economic assumptions. The view that economic factors are fundamental or dominant, despite the importance of biological, psychological, political, cultural, and social factors.
Economic Enterprise (Economic Unit)
A business of sufficient resources to provide an acceptable standard of living for a family, often termed an economic unit.
Economic Externalities
Effects of resource allocation decisions which are not included in the market mechanism, and as such have no economic influence on resource allocation decisions; these constitute failures of classical market mechanism as a resource allocation tool. Also, costs or benefits that occur whenever the activities of one or more persons affect the welfare or production functions of others who have no direct control over that activity.
Economic Growth
Increased financial activity in real terms over time. It may include building infrastructure, resources, and public relations. It does not necessarily correspond to increased production of physical goods.
Economic Life
The time extending from the date of installation [of a facility] into service to that date when the facility is no longer economically profitable to use.
Economic Scarcity (Resource Scarcity)
The condition in which a limited number of marketable goods are desired in higher quantities than are available. The "scarcity" can be reduced either by increasing the available goods and maintaining a low price, or by raising the price of the goods until the number of people willing to pay the higher price are at the supply level. Which is the socially superior method depends on supply costs and the existence of economic externalities.
Economic Subregion
These U.S. Bureau of the Census areas are combinations of state economic areas. The 510 state economic areas in the U.S. census are consolidated into economic subregions which cut across state lines but which, preserve to a great extent the homogeneous character of the state economic areas.
Ecosystem (Bioc(o)enosis, Biogeoc(o)enosis, Biogeoc(o)enose)
(1) A complete, interacting system or unit of organisms in a space considered together with their environment, e.g., a marsh, a watershed, a lake, etc., mentally isolated for purposes of study or management. A flow of energy leads to clearly defined food and feeding relationships, biologic diversity, and biogeochemical cycles (i.e., exchange of materials between living and nonliving parts) operating as an integrated system. "Ecosystem" is the preferred term in English while "biocoenosis" or "biogeocoenosis" is preferred by writers using or familiar with the Germanic and Slavic languages. (2) A nameable natural unit that includes not only the total array of plant and animal species in an environment, but also the energy to power the system. (3) A biotic community plus its abiotic environment. (4) Any complex of living organisms with its environment. (5)An interconnected community of plants and animals, including humans, and the physical environment within which they interact. (USFS 1999)
Ecosystem Diversity
The variety and relative extent of ecosystem types, including their composition, structure, and processes within all or a part of an area of analysis.
Ecosystem Dynamics
Characteristic and measurable processes and associated change within an ecosystem such as succession, energy flow, nutrient cycling, and community metabolism.
Ecosystem Integrity
The completeness of an ecosystem that, at multiple geographic and temporal scales, maintains its characteristic diversity of biological and physical components, spatial patterns, structure, and functional processes within its approximate range ofhistoric variability. These processes include disturbance regimes, nutrient cycling, hydrologic functions, vegetation succession, and species adaptation and evolution. Ecosystems with integrity are resilient and capable of self-renewal in the presence of the cumulative effects of human and natural disturbances.(USFS 1999)
Ecosystem Stability
(1) A measure of the tendency of an ecosystem to persist, relatively unchanged, through time; (2) A measure of the resilience of an ecosystem to perturbation.
Ecosystem Structure
The biological and physical attributes that shape ecological systems; biotic attributes include population size, structure and range; fdliage~density and layering, snags, large woody debris or the size, shape and spatial relationships of cover types within a landscape; physical attributes include soil and geologic substrate variables, slope and aspect, or stream gradient.(USFS 1999)
A transition between two communities or vegetation types. It is a junction zone narrower than the adjoining community areas themselves. The ecotonal community commonly contains many of the organisms of each of the overlapping communities and, in addition, organisms that are characteristic of and often restricted to the ecotone. Often, both the number of species and the population density of some of the species are greater in the ecotone than in the communities flanking it. Organisms which occur primarily or most abundantly or spend the greatest amount of time in contiguous communities are often called "edge species," while the tendency for increased species richness and density at community junctions is known as the "edge effect."
Diverse tourism that include a major part of interest, activities, and successes related to ecological topics, environmental awareness and education, and experiencing the outdoor nature of places to which people travel. It includes the services and structures that support these activities. It includes the impacts, positive and negative, of such activities on the environment and human communities. Hector Ceballos-Lascurain, Mexico, is said to have coined the word ecotourism in 1983.
A genetically distinct race or subdivision of species adapted to local habitat and climate. These significantly different genetic groups are broader than a biotype and narrower than a species. Ecotypic variation must be considered before transferring information on impacts to a species in one region to the same species in another region because different ecotypes may respond differently to the same level of effect.
An adjective suggesting the soil complex or soil as a system.
Edaphic Factor (Soil Factor) -
A characteristic or factor of the soil environment (opposed to physiographic or climatic factors), which limits the existence or development of an organism or community, e.g., low nutrient or micro-nutrient concentrations, or the presence of toxic concentrations of certain substances, or insufficient or excess soil moisture conditions.
The linear elements in a view or scene which are noted (or considered by the observer) as being the dividing lines between major components. "Edges" serve as visual boundaries e.g., land-water boundaries or forest-meadow boundaries. Also, for animal analyses, the volume that is the living space having length, width, height, and species-specific quality (or relevance to life requirements.)
Edge Effect
The effect created in animal populations in the edge volume between two types. This portion of the forest environment, for example, provides a diversity of wildlife food and cover, where grass, forbs, and shrubs form a narrow border around forest clearings. Greater animal richness and abundance is the "effect".
Environmental Data and Information Service. EDIS is a part of the National Oceanic and Atmospheric Administration and offers an extensive level of service through each of its environmental data centers. EDIS maintains a bibliographic database (ENDEX).
Effect (Impact), Economic
The change, positive or negative, in economic conditions, including the distribution and stability of employment and income in affected local, regional, and national economies, which directly or indirectly result from an actively, project, or program.
Effect (Impact), Physical, Biological
The change, positive or negative, in the physical or biological conditions which directly or indirectly results from an activity, project, or program.
Effect (Impact), Social
The change, positive or negative, in social and cultural conditions which directly or indirectly result from an activity, project, or program.
Effective PC
Timber sale purchaser road costs that can be credited against the amount bid on a timber sale.
Effectiveness Index
The index used in cost-effectiveness analysis, one emphasizing achieving objectives, not simply efficiency of any activity.
Effectiveness Test
In choosing among alternatives in planning for water and related land resources, the "effectiveness test" refers to technical performance of the plan and the level of contribution to achieving each of the objectives.
An expression of output per unit of input or cost.
Efficiency Test
Using the efficiency test in choosing among alternatives in planning for water and related land resources requires that among all acceptable alternatives (Federal and non-Federal, water and non water, structural and nonstructural) a given alternative plan should be the least costly means (considering all adverse effects) of achieving the objectives.
Any liquid flowing out of the ground or from an enclosure to the surface flow network, typically the liquids discharged from domestic, industrial and municipal waste collection systems or treatment facilities.
A belief or social philosophy that all people are equal in intrinsic worth and are entitled to equal access to the rights and privileges of their society. It may include leveling of social, political and economic inequalities. Exactly what aspects of social reality are considered in order to decide what should be equal and what unequal is a rather complex problem sometimes involves self contradictions: e.g., equality of opportunity can result in unequal distributions, because people have different abilities, degrees of motivation, and luck: equality of resource inputs in different schools may result in inequality in educational achievements of the students, (if the latter began with unequal advantages), and attempting to increase student achievement, different schools might require unequal resource inputs in order to overcome the initial handicaps of some students.
See Environmental Impact Statement.
In economics, a measure of responsiveness of the quantity demanded or supplied to changes in price. Elasticity measures the degree to which price is effective in calling or holding back quantity. Small price changes do not influence demand for highly elastic commodities.
The individuals at the top stratification hierarchy, such as economic, social prestige, or politic. "Power elite" are those with a high degree of coordination and a set of common interests among those in top corporate and governmental positions.
See Pluralism.
Elk Effective Cover
A concept of habitat effectiveness, but including implications of both habitat productivity and security.
Elk Habitat Potential
A poor synonym for carrying capacity, for habitat capability, and for elk use potential.
Elk Management Unit
An administrative or habitat analysis unit.
Elk Use Potential
A scaled representation of maximum possible use by elk; a comparison of current and predicted use.
Elk Vulnerability
A measure of elk susceptibility to being killed during the hunting season, antonym for security during the hunting season.
Eltonian Pyramid
See Pyramid of Numbers.
Emergence (of a plant)
(1) Appearance of the plant above ground after germination in the soil. (2) Elongation of the hypocotyl out of the soil into the air followed by the beginning of growth of the epicotyl.
Eminent Domain
The right or power of government, subject to constitutional and statutory limitations, to take private property for public use after making just compensation. The use of this power is limited by the "Due Process of the Law" clause in the 14th Amendment of the United States Constitution.
Endangered Species
Species listed as nationally in danger of extinction throughout all or a significant portion of their ranges by current Federal Register Final Rule making by the Secretary of Interior as endangered in accordance with the 1973 Endangered Species Act and subsequent acts. An animal that may become extinct because of loss or damage of habitat within the original range of the species.
Endangered Species Act of 1973 (PL 93-205; 87 Stat. 884, etc.)
Repeals and replaces the Endangered Species Conservation Act of 1969. An act to provide a means whereby ecosystems upon which endangered species and threatened species depend may be conserved, to provide a program for the conservation of such endangered species and threatened species, and to take such steps as may be appropriate to achieve the purposes of the (relevant) treaties and conventions.
Native or confined to a certain region; having a comparatively restricted distribution (as a disease caused by an indigenous pathogen)
Endemic Organism
A taxonomic category (e.g., genus, species, and variety) the natural occurrence of which is confined to a certain region and the distribution of which is relatively limited.
The analysis and use of knowledge of embodied energy and the flow of energy in systems; the study and use of the knowledge of comprehensive energy budgets in designing and managing systems.
Engineering Solution
Development or assembly and use of technical solutions to solve (or at least minimize) problems associated with particular land uses or land use practices.
Improvement on existing or projected natural biological conditions.
Enteric Bacteria
Those which originate in the intestines of warm-blooded animals.
Entomology, Forest
Studies and practices dealing with insects in relations to forests and forest products.
(1) The passage of organisms through the cooling systems of, for example, power plants. (2) Ambient water being brought into the cooling plumes as the effluents are discharged from power plants.
The complex of factors (those of the atmosphere, hydrosphere, lithosphere, and biosphere) that act upon an organism or ecological community and ultimately determine its form and survival.
Environment, Human
The aggregate and interaction of all the external conditions and influences affecting the life and development of an individual or society.
Environmental Analysis
Determining the probable effect of a project upon the renewable resources, considering the physical, biological, natural, social, and economic factors and their relations. This analysis is made in accordance with section 102 (2) (c) of NEPA (PL 91-190) with later amendments.It is also the process of preparing an environmental assessment or environmental impact statement and the decision about whether to prepare an environmental assessment or impact statement. It is an analysis of alternative actions and their predictable short-term and long-term environmental effects.
Environmental Analysis Report (EAR)
A report on environmental effects of proposed Federal actions which may require an Environmental Impact Statement (EIS) under section 102 of the National Environmental Policy Act (NEPA). The EAR is an "in-house" document of varying degrees of formality that becomes the final document on environmental impacts for those projects that, because their effects are minor, do not require a formal EIS. Although not formally prescribed under NEPA, the EAR is the document normally used to determine whether section 102 of NEPA applies to the project in question, and as such is subject to court challenge if no EIS is filed.
Environmental Assessment (EA)
A public document that serves to (1) provide sufficient evidence and analysis for determining whether to prepare an environmental impact statement or to find no significant impact and; (2) aid in agency's compliance with the NEPA when no environmental impact statement is necessary.
Environmental Corridor (Buffer, Buffer Strip, Buffer Zone, Greenway)
A strip of land designed to protect the natural environment of an area and to prevent undesirable encroachment such as commercial development along a stream. Also a thin habitat connecting two similar areas and said to reduce "fragmentation."
Environmental Effect
An outcome, result, or consequence to the environment brought about by some force, project, or action. Primary (direct) impacts are generally caused by action inputs (such as road construction). Secondary (indirect) impacts commonly result from action outputs, (such as improved access leading to overload of recreation visitors).
Environmental Impact Analysis (Environmental Analysis, Environment Assessment, Environmental Impact Assessment)
An activity that considers, estimates, and evaluates, using a systematic, interdisciplinary approach, the physical, natural, and social factors, the probable effects of a plan or proposed project upon local systems. An assessment precedes an EIS.
Environmental Impact Statement (EIS)
A statement of environmental effects required for major Federal actions under Section 102 of the National Environmental Policy Act (NEPA), and released to the public and other agencies for comment and review. It is a formal document that must follow the requirements of NEPA, the Council on Environmental Quality (CEQ) guidelines, and directives of the agency responsible for the project proposal. The Final EIS is a revision of the draft environmental impact statement and includes public and agency responses to the draft. It must meet legal requirements and is the document used as a basis for judicial decisions concerning compliance with NEPA. An impact statement includes the following points: (1) the environmental impact of the proposed action, (2) any adverse impacts which cannot be avoided by the action, (3) the alternative courses of action, (4) the relationships between local short-term uses of the human environment and maintaining and enhancing long-term productivity, (5) a description of the irreversible and irretrievable commitment of resources which would occur if the action were accomplished. The draft is the DEIS and the final statement the FEIS.
Environmental Impact Statement, Draft (DEIS, Draft Environmental Statement)
The version of the statement of environmental effects required for major Federal actions under section 102 of the National Environmental Policy Act (NEPA), and released to the public and other agencies for comment and review. It is a formal document that must follow the requirements of NEPA, the Council on Environmental Quality (CEQ) Guidelines, and directives of the agency responsible for the project proposal. The Draft and Final EIS are for information only. A finding of a significant loss or hazard, alone, cannot prevent a project being started. Many states and communities have environmental impact assessment laws.
Environmental Management System (EMS of the USFS)
The part of the overall management system that includes organizational structure, planning activities, responsibilities, practices, procedures, processes, and resources for developing, implementing, achieving, reviewing, and maintaining the environmental policy of the planning unit. EMS audits are systematic and documented verification of whether the EMS conforms to audit criteria set by the organization and results communicated to managers.
Environmental Modification
Deliberate or unintentional changes produced by people that act upon an organism or community to influence its development or existence.
Environmental Planning
Planning which considers the environment as a physical and biological system, one that is spatial, having direct experiential and sensory surroundings, and one that is a primary conditioner of physical and psychological development, health, and longevity for each human. It is strongly concerned with human activities taking place in the outdoors and those that reconcile their demands for and impacts upon the environment. It seeks to ensure that policies, programs, designs and actual developments incorporate forecasts of the effects upon environmental amenity and natural system functions and structures so as to anticipate, evaluate, and prepare for the consequences of decisions in light of present and future values.
Environmental Psychology
That area of psychology which deals with environmentally induced behavior or mental states of individuals or groups, e.g., where "behavioral psychology" may attempt to alter self concepts through operant conditioning, "environmental psychology" seeks to determine how the every-day physical environment affects human behavior. It is also a study of human perception of elements in the environment or of different types of environmental settings. Perception includes direct sensory knowledge and cognitive discrimination expressed in terms of preference rated on a scale of desirability. It also includes learning and the knowledge of how a set of behaviors (e.g., littering, vandalism, and hunting) is changed.
Environmental Quality
The perceived condition, the sum of the forces and factors which influence people's satisfaction and health in their work, leisure, living conditions, and community. Management, conservation, preservation, restoration, or improvement can enhance it in cultural and natural systems. Major systems of concern are areas of natural beauty; water, land, and air; biological resources and select ecosystems; geological, archeological, and historical; and resources perceived to be of great future value. "Quality" may be high or low. It may be present without people, but human perception, valuation, and judgement are needed to arrive at its expression. Individuals perceive it; a group expression (e.g., various statistical or consensus values) about it may be derived.
Environmental Reports
(1) Environmental analysis report (EAR). A report on environmental effects of proposed federal actions which may require an environmental impact statement (EIS) under section 102 of the National Environmental Policy Act (NEPA). The EAR is an "in-house" document of varying degrees of formality that becomes the final document on environmental impacts for those projects that, because their effects are minor, do not require a formal EIS. Although not formally prescribed under NEPA, the EAR is the document normally used to determine whether section 102 of NEPA applies to the project in question, and as such is subject to court challenge if no EIS is filed. If a formal EIS is prepared, an existing EAR becomes the information base for the EIS. See Environmental Impact Statement, Final. (2) Environmental impact statement (EIS, 102 statement, environmental statement). A document prepared by a federal agency in which anticipated environ mental effects of a planned course of action or development are evaluated. A federal statute (section 102 of the National Environmental Policy Act of 1969) requires that such statements be prepared. It is prepared first in draft or review form, and then, in final form. Although "environmental impact statement" (EIS) is the popularly used term, some prefer the term "environmental statement" (ES), feeling that EIS is an inaccuracy due to the negative connotations of the word "impact." Section 102 (C) of NEPA mentions that impacts, effects, alternatives, etc. will be contained in the required "detailed statement." Consequently, to name one feature and to exclude others is inaccurate. Thus, the draft is the DES and the final statement the FES. (3) Environmental Impact Statement, draft (see DEIS, draft environmental statement, DES). See Environmental Impact Statement and Environmental Impact Statement, Final. (4) Environmental impact statement, final (EIS, final environ mental statement, FES) The final version of the statement of environmental effects required for major federal actions under section 102 of the National Environmental Policy Act (NEPA). It is a revision of the draft environmental impact statement to include public and agency responses to the draft. This term is also used for similar statements prepared to comply with state and local laws patterned after NEPA.
Environmental Science
A multi- and inter-disciplinary science attempting to measure and evaluate the influence of people on the structure, function and relations of systems upon which humans depend, and the influence of management on these systems and their contributions to human objectives.
Environmental System
A general phrase meaning a specified or defined set of interacting components in the environment, understood to have some degree of integrity, often having the characteristics of a general system. It may be a farm, a forest, or a watershed and is usually more general and inclusive of human factors than "ecosystem."
Ephemeral Stream (Intermittent Stream, Perennial Stream)
A stream or portion of a stream that flows only in direct response to precipitation. It receives little or no water from springs and no long-continued supply (less than a month and often only during storm events) from snow or other sources. Its channel is at all times above the water table.
Epicormic Branching
Branches which grow out of the main stem of a tree, arising from buds under the bark. Severe branching increases knottiness, thereby reducing the quality of lumber.
That region of a body of water that extends from the surface to the thermocline and does not have a permanent temperature stratification; the volume above the hypolimnion.
Bacterial and fungal films on rocks and dead material in streams.
Equilibrium, Ecological
A dynamic state of quasi-balance in which the elements of a physical or biological system partition energy flow in a uniform manner, with outflow balancing inflow about which the system fluctuates to some small degree. (Often applied to an animal population at zero growth, to the steady interaction of two species, predators and prey, to the energy flow through an ecosystem, and to the nutrient cycling pattern of an ecosystem). (brief zero-rate-of-change in a fluctuating system).
Equilibrium Price
The price at which consumers will be willing to take exactly the amount that sellers want to place on the market at the price where marginal revenue of a product equals marginal cost.
The relative ease with which one soil sample erodes under specified conditions as compared with other soils under the same conditions.
The group of processes whereby earth or rock material is worn away, loosened, or dissolved and removed from any part of the Earth's surface by wind, water, ice, or gravity. It includes the processes of weathering, solution, corrosion, and transportation. It is often classified by the eroding agent (wind, water, wave, or raindrop erosion) and/or by the appearance of the erosion (sheet, rill, or gully erosion) and/or by the location of the erosion activity (surface, or shoreline) or by the material being eroded (soil erosion or beach erosion). "Raindrop erosion" always takes the form of "sheet erosion" though wind action or the movement of thin sheets of water can also cause "sheet erosion" over the ground surface. "Sheet", "gully" and "rill erosion" are all forms of "soil erosion." "Sheet" and "rill erosion" are the two forms of surface erosion. "Beach erosion" is always "shoreline erosion", e.g., because not all shorelines are beaches; "shore line erosion" is not always "beach erosion". The term accelerated erosion is used in comparing erosion caused by human activities with that occurring at natural rates (i.e., geologic erosion).
Erosion, Accelerated
Erosion that is much more rapid than natural erosion, or geologic erosion, and occurring primarily as a result of the influence of the activities of people or, in some cases, of animals or natural catastrophes that expose bare surfaces (for example, fires).
Erosion, Bank
Destruction of land area by active cutting of stream-banks.
Erosion, Beach
The retreat of the shoreline of large lakes and coastal waters caused by wave action, shore currents, or causes other than subsidence.
Erosion, Geologic (Natural Erosion)
Gradual wearing away of the land surface which occurred prior to the occupancy of a land area by people or the present day wearing-away which is not due to the activities of people but due to natural environmental conditions of climate, vegetation, etc.
Erosion, Gully
Removal of soil and formation of relatively large channels or gullies cut into the soil by concentrated surface runoff. Gullies are too deep to be obliterated by ordinary tillage practices.
Erosion Hazard
The possibility of a soil eroding when disturbed, based on soil type, topography, and vegetative cover.
Erosion, Normal
The gradual erosion of land used by people which does not greatly exceed natural erosion.
Erosion, Rill
Removal of soil by the cutting of numerous small (several inches deep), but conspicuous, water channels or tiny rivulets by concentrated surface runoff usually from cultivated or exposed soils. It is intermediate between sheet erosion and gully erosion.
Erosion, Sheet
The removal of a fairly uniform layer of soil from the land surface by runoff water or wind without the development of conspicuous water channels.
Erosion, Splash (Raindrop Erosion)
The spattering of small soil particles caused by the impact of raindrops on wet soils. The loosened and spattered particles may or may not be subsequently removed by runoff.
Escape Cover
Vegetation dense enough to aid animals in escaping from potential enemies, including hunters; a synonym for security, security area, security cover, and hiding cover, but imprecise.
(1) The number, or proportion, of elk or other wildlife surviving the hunting season (not escape cover). The emphasis may be on specific age and sex classes of elk. (2) Also fish passing a dam or waterway blockage.
Essential Elements
A chemical element required by green plants for normal growth, such as the primary essential elements: hydrogen, oxygen, nitrogen, phosphorus, and potassium; secondary essential elements: sulfur, calcium, and magnesium; and the trace (or minor) elements: iron, boron, manganese, copper, zinc, and molybdenum. The last six, and traces of other elements, are required in only minute quantities.
An acceptable spelling variation of aesthetics. See Aesthetics.
Estuarine Sanctuary
A research area which may include any part or all of an estuary, adjoining transitional areas, and adjacent uplands, constituting to the extent feasible a natural unit, set aside to provide scientists and students the opportunity to examine over a period of time the ecological relationships within the area.
Estuary (Estuarine)
All or part of the wide mouth of a navigable or interstate river or stream or other body of water having unimpaired natural connection with open sea tides and within which the sea water is measurably diluted with fresh water from land runoff.
Eury- (Euroky-)
A prefix denoting ability (of an organism) to tolerate large changes in environmental conditions. For example, eurythermal describes organisms that can tolerate large temperature ranges. Also see Steno-.
Characteristic of waters rich in dissolved inorganic or mineral nutrient materials and exhibiting a paucity or complete lack of oxygen in the bottom waters as a consequence of high primary production and the high nutrient content.
The process of over-fertilizing (over-enrichment) of a body of water by nutrients (or pollutants) that produces more organic matter (e.g., algal growth) than the self-purification processes can overcome. A low oxygen content results.
(1)Examination or judgement about the worth, quality, significance, amount, degree, or condition of something. Assessing or estimating value. (2)Evaluation (USFS 2005). A comprehensive analysis of social, economic, and ecological conditions and trends relevant to a unit. The analysis of monitoring data that produces information needed to answer specific monitoring questions. Evaluation may include comparing monitoring results with a predetermined guideline or expected norm that may lead to recommendations for changes in management, a land management plan, or monitoring plan. Evaluations provide an updated compilation of information for use in environmental analysis of future project and activity decisions.
The process by which water is changed from the liquid into the vapor state. In hydrology, evaporation is vaporization that takes place at a temperature below the boiling point. It is usually measured with evaporation pans.
Loss of water from a land area through transpiration of plants and evaporation from the plant and other surfaces.
Continuous supply of products over a given time period.
Even-Aged Management
The application of a combination of actions, a system, of growing, harvesting, and reproducing timber in stands of trees that grow together and, within each, are of essentially the same age (at least within 10-year classes). Managed even-aged forests are characterized by a distribution of stands, among which,there are varying ages (and, therefore, tree sizes throughout the forest area). Cutting methods producing even-aged stands are clearcut, shelterwood, or seed tree. (1) Clearcutting - The removal in a single cut of the entire standing crop of trees in a stand. It prepares the area for rapid seed germination and growth of a new even-aged stand. (2) Shelterwood Cutting - A method designed to establish a new crop under a remaining portion of the old stand that provides both a seed source and protection of the site and seedlings. (3) Seed Tree Cutting - The removal in one cut of the mature timber from an area with a small number of seed-bearing trees retained for regeneration. The difference in age between trees forming the main canopy level of a stand usually does not exceed 20 percent of the age of the stand at harvest rotation age. Regeneration in a particular stand is obtained during a short period at or after the time that a stand has reached the desired age or size for regeneration and is harvested.
Even-aged Regeneration Harvest
A timber cutting procedure by which a new age class of trees is created; the methods include clearcutting, seed tree, shelterwood, and coppice.
Even-Aged Stand
A forest stand composed of trees having no, or relatively small, differences in age. By convention the maximum difference admissible is generally 10 to 20 years, though with rotations of less than 100 years differences up to 25 percent of the rotation period may be admissible in some policy formulations.
Trees which retain green foilage throughout the year. Not all conifers are evergrees (e.g., tamarack).
Exempt Stock
Livestock that are grazed on Federal land free of charge. Usually confined to animals used for domestic purposes; saddle horses, milk cows, etc.
Existence Value (Bequest Motive)
The external benefit of natural environments (or any kind of good but often of wilderness) that accrues to individuals having no intention of ever visiting the site or using the good in question. These people are willing to give up resources simply to know that the area, feature, or good exists in a particular condition. The concept of "existence value" has been recognized for some time. John Krutilla (1967) has used the term "bequest motive" to express roughly the same idea. Existence value is preferred because it is less specific in its connotations about motivations; i.e., it does not imply handing something down to later generations.
Existing Visual Conditions
The present state of visual alteration which is measured in six degrees (untouched, unnoticed, minor disturbance, disturbed, major disturbance, drastic disturbance) of deviation from the natural appearing landscape.
Exotic Organism
Any organism (plant or animal) that is not native in the area where it now occurs (introduced). "Invasive" may include "weedy" natives as well as invasive exotics. " A rose in a cornfield is a weed." Exotics may (or not) be invasives as can "native" plants.
The rules governing social situations, which are specific to particular societies and even to groups within societies. These are notable only when violated. Expectations are normative, in that they reflect what people believe ought to happen, and statistical, in that they express what people believe probably will happen. These may be probability statements or 1.0 minus the probability of a failure or bad outcome.
Experimental Forest
A Designated area managed for research purposes, e.g., for watershed or timber growth study.
Utilization of a resource for expected profits or benefits; the number or proportion of animals removed by hunting, fishing or other means.
Export Base Analysis (Economic Base Analysis)
A multiplier analysis method for estimating regional economic effects of projects. It is particularly suited to rural areas. The economy is divided into two sectors, "export" and "service". The export sector includes all goods and services produced for consumption outside the region being evaluated. The service sector includes all other economic activity. The export sector is assumed to create the need for the service sector, and a multiplier is calculated for each export industry, relating employment in the service sector to the level of activity in that industry. By determining project effects on the export industries, the total economic effects can be estimated.
Exposure (Slope Orientation, Aspect)
The compass direction toward which the slope of a land surface faces. Transformations are recommended, i.e., 360o is likely to be equivalent to 1o or 2o or 358o or 359o.
Extant plants and animals which are relics of the flora and fauna or other geologic time periods and are of historic or scientific significance are considered under botanical areas or zoological areas, respectively, and are identified and formally classified primarily because of their recreational values.
See Economic Externalities. An unanticipated or unrecognized side effect (eiher positive or negative) on a third party resulting from a transaction that occurs between two other parties; the side effect is external to the contracting parties economic decisionmaking.
Being no longer found anywhere in the world (e.g., passenger pigeon) without reference to cause(s).
Eradication of a species (total) from an area
Extractive Economics
The economics of industries which remove natural resources and supply them to other industries as raw materials. The economic analysis of these industries is more often complicated by depletion of fixed stocks, resource ownership ambiguities, and "common pool" externalities than is true with other types of industries.
Extrinsic Resource
Recreational values created by human-made changes, adaptations, and additions to basic natural (i.e., intrinsic) resources made by people, e.g., mill ponds, historic sites, tourist service facilities, archeological sites, etc.

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Last revision January 17, 2000.