Yosemite National Park - Glossary of Terms (U.S. National Park Service)

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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

100-year floodplain: The land adjacent to a river corridor that would be covered by water during a 100-year flood event. A 100-year flood event has a 1% probability of occurring during any given year.

A-weighted noise leve (dBA) Noise intensity as measured with devices that have the same sensitivity to sound frequencies as the human ear.

Abutment: A structure that supports the ends of a bridge or dam.

Action alternative: An alternative that proposes a change to existing conditions or current management direction. The environmental consequences of an action alternative are analyzed in relation to the No Action Alternative. Also see No Action Alternative.

Adaptive reuse: A new use for a structure or landscape other than the historic use, normally entailing some modification of the structure or landscape. Also see Rehabilitation (cultural resources).

Affected environment: Existing natural, cultural, and social conditions of an area that are subject to change, both directly and indirectly, as a result of a proposed human action.

Air quality: A measure of health and visibility-related characteristics of air, often derived from quantitative measurements of the concentrations of specific injurious or contaminating substances.

Alluvial: Processes by which sediment is deposited by running water.

Alluvium: Sediment deposited by a stream or other body of running water.

Alternatives: Sets of management elements that represent a range of options for how, or whether to proceed with a proposed project. An environmental assessment analyzes the potential environmental and social impacts of the range of alternatives presented, as required under the National Environmental Policy Act (NEPA).

Ambient noise: The existing sounds at a given location coming from all sources, both near and far.

Anaerobic: Existing in the absence of free oxygen.

Annosus root disease (Root Rot):Annosus root disease is a widespread native fungus. In pines, the fungus spreads through the root system, attacking and killing the inner bark and sapwood. Within two to six years after initial infection, the fungus reaches the root crown and girdles the tree. The tree dies, but the fungus remains active as a saprophytic wood-decaying organism within roots and the butt of the dead tree. Pines weakened by annosus root disease are often killed by bark beetles. Incense-cedars, however, are not affected by beetles and will stand green for many years, until the disease finally weakens the structure enough to cause failure. Cedars are thought to act as a reservoir for annosus root disease because they take so long to die.

Anthropogenic: Resulting from the influence or actions of human beings, e.g., the burning of the Valley floor by American Indians to clear brush.

Aquatic state: The period in the life cycle of some organisms that is spent almost entirely in water. For example, many insects have an aquatic larval stage.

Archeological resources: Historic and prehistoric deposits, sites, features, structure ruins, and anything of a cultural nature found within, or removed from, an archeological site.

Armillaria root rot: A native plant disease primarily affecting oaks, but other tree species as well; sometimes exacerbated by management activities. It can also result in tree hazards.

Asphalt pulverizing: Pulverizing is the process of breaking apart existing roadway asphalt into an aggregate (similar to creating mulch from a tree), sometimes blending the recycled aggregate with new aggregate, and reusing it as subgrade for newly laid asphalt. Pulverizing is a cost effective and environmentally friendly way to reconstruct existing pavement. This process eliminates the expensive and environmentally damaging excavation and trucking of the existing asphalt, and it creates a stronger base.

Average level (Leq): The constant sound level for a specific measurement period that has the same total sound energy as the actual varying sound levels recorded over the period.

Background noise: The all-encompassing sound associated with a given environment at a specified time, usually a composite of sound from many sources and directions. Background noise remains in a given location in a given situation when all uniquely identifiable, discrete sound sources are eliminated, rendered insignificant, or otherwise not included.

Bank: The area below the ordinary high water mark in a river or stream. The ordinary high water mark is defined as the 2.33-year flood by the U.S. Army Corps of Engineers.

Barrier stones: Naturally shaped granite boulders placed along roadway and/or roadside parking locations (either partially buried or fully exposed) to define an area or make an area inaccessible.

Base of talus: See Talus slope zone.

Bed: Refers to the number of bed spaces assigned to employees in a given location. A bed could represent a multi-room house, a dormitory, or single-room unit. For example, a single-family house dedicated to one employee is considered to be one bed, regardless of the number of family members living in the same residence.

Berm: Mound of shaped earth intended to direct traffic away from roadway shoulders or to channel hydrologic processes.

Best Management Practices (BMPs): Effective, feasible (including technological, economic, and institutional considerations) conservation practices and land- and water-management measures that avoid or minimize adverse impacts to natural and cultural resources. BMPs may include schedules for activities, prohibitions, maintenance guidelines, and other management practices.

Biodiversity: Or biological diversity, includes genetic diversity within species, species diversity within a community, and diversity in a full range of biological communities. An area is considered biologically diverse when it includes rich and stable populations of native species that are naturally distributed across the landscape.

Biological community: An association of plants and animals in a region dominated by one or more prominent species or by a physical characteristic (e.g., California black oak community).

Biota: All plants, animals, and microscopic life forms that make up a biological community or region.

Biotic: Of or produced by living things; composed of plant, animal, or microscopic life forms.

Braided stream system: A stream pattern that is characterized by the division of water flow into more than one channel. A basic characteristic of this pattern is the diversion of a single trunk channel into a network of interconnected branches and the formation of interspersed islands.

California black oak woodland: A vegetation community dominated by California black oak (Quercus kelloggii). Other species that may be present include canyon live oak, California buckeye, Douglas-fir, incense-cedar, and ponderosa pine. The canopy can be continuous, intermittent, or savanna-like. Shrubs may or may not be common. Ground layer vegetation is sparse or grassy (Sawyer 1995).

Cabin (cultural resource): A small, rustic residential structure usually occupied seasonally.

Cabin (lodging): A structure containing one to four lodging units, as defined in the 1992 Concession Services Plan/EIS.

California Wilderness Act of 1984: A federal law that designated a number of additional wilderness areas in California, including those in Yosemite National Park. 94.5% of Yosemite National Park is designated wilderness.

Cambium: A thin layer of cells between the wood and bark in most vascular plants; the cells increase by division and differentiate to form new wood or bark.

CEQ Regulations: The Council on Environmental Quality (CEQ) was established by the National Environmental Policy Act (NEPA) and given the responsibility for developing federal environmental policy and overseeing the implementation of NEPA by federal agencies.

Choosing by Advantages: A decision-making process used in planning to analyze and refine the alternatives.

Colluvial soils: Loose earth material (such as rock fragments, sand, etc.) that accumulates on steep slopes or at the base of talus slopes through the action of gravity.

Community: When used in a social or political context, refers to the group of people living in a particular area. When used in a biological context, any group of interacting organisms belonging to a number of different species that occur in the same habitat. Also see Biological community.

Concessioner: A private commercial entity that conducts business under contract with the National Park Service in Yosemite National Park to provide food, lodging, retail, recreation, and other services to park visitors. The primary concessioner in the park is Delaware North Corporation. Other concessioners include Yosemite Medical Clinic, The Ansel Adams Gallery, El Portal Market, and El Portal Chevron.

Concession Services Plan: The 1992 amendment to Yosemite’s General Management Plan that guides the management of concession enterprises, such as lodging, food, retail, and other commercial services in Yosemite National Park. This plan serves as the basis for contracts between the National Park Service and the park’s primary concessioner.

Conifer invasion: The progressive growth of coniferous trees, such as pines and incense cedars, into areas that formerly did not support these species. Over the last 150 years human-caused changes (such as alteration of soil moisture and suppression of a natural fire regime) have encouraged unnatural rates of conifer spread, reducing the size and continuity of meadows in Yosemite Valley.

Connectivity: The degree to which physical connections are maintained between large areas of habitat and patches of habitat, and between different types of habitat. Connectivity increases biodiversity and enhances reproduction and survival of species. Also see Habitat fragmentation.

Cottage: A lodging structure containing five to eighteen lodging rooms, as defined in the 1992 Concession Services Plan/EIS.

Crownsprout: An adaptation of plants to produce new growth from a stump or burl typically damaged by cutting or fire. New growth often appears as circular or crown-like.

Cultural landscape: A geographic area, including both cultural and natural elements, associated with a historic event, activity, or person, or exhibiting other cultural or aesthetic values. There are two primary types of cultural landscapes in Yosemite Valley: historic designed landscapes, such as The Ahwahnee and the Yosemite Village Historic District; and ethnographic landscapes, such as the entirety of Yosemite Valley.

Cultural Resources: Properties such as landscapes or districts, archeological sites, historic properties, buildings, structures, objects, or traditional cultural resources, that are usually greater that 50 years of age and possess architectural, historic, scientific, or other technical value. By their nature, cultural resources are non-renewable.

Curbing: Reinforced concrete and/or rectangular cut granite placed at selected roadside parking locations and/or along roadway shoulder.

Cumulative effects: Effects on the environment that result from the incremental impacts of an action when added to other past, present, and reasonably foreseeable future actions, regardless of which agency (federal or non federal) or person undertakes such actions. Cumulative effects can result from individually minor, but collectively significant, actions taking place over a period of time.

Day visitor: All visitors who do not spend the night in the park.

Day-Night Average (DNL): An average of daytime and nighttime noise levels with an adjustment that takes into consideration the greater need for quiet at night.

Debitage: Waste flakes of stone created during the process of stone tool manufacturing. Also see Lithic.

Debris flow: Soil, rock, and other materials that are rapidly transported by water and gravity. Debris flows occur in a variety of environments throughout Yosemite, ranging from steep ephemeral and perennial stream channels below cliffs to nearly flat alluvial fans adjacent to the Merced River floodplain.

Decadent trees: Stands of trees with greatly reduced growth, usually occurring as one of three types: (1) over-mature trees nearing end of normal life, (2) younger trees limited by site conditions such as soil deficiencies, and (3) overcrowding due to exclusion of natural and cultural fires.

Decibel (dBA): A unit of measure of sound intensity.

Decompaction: A natural resource restoration technique that includes loosening or breaking up unnaturally compacted soils to facilitate water movement and root growth.

Degradation (natural resources): Refers to negative impact(s) to natural resources or natural processes. The impact may be singular or cumulative; the extent may be local or ecosystem-wide. The term degradation is used broadly and may refer to: reduction in habitat size, reduction in extent of plant populations, declining species vigor exhibited as reduced population numbers, reduced reproductive success, increased mortality rates, and/or decreased percent of available habitat utilized.

Deluxe Lodging: A type of overnight visitor lodging having the largest number of amenities and, correspondingly, the highest price range found in Yosemite National Park. The only deluxe accommodations provided in Yosemite are at The Ahwahnee. As required by law, prices are established by the National Park Service after considering market forces and relevant factors, as well as reviewing a sample of comparable facilities operated under similar conditions in California. Double occupancy prices for deluxe lodging in 1999 ranged from $241 - $313, plus tax, depending on room type and season.

Design day: A planning term meaning a typically busy day; the level of visitation for which various facilities, systems, and programs would be designed to handle.

Designed historic landscape: A landscape significant as a design or work of art, that was consciously designed and laid out either by a master gardener, landscape architect, architect, or horticulturist to a design principle, or by an owner or other amateur according to a recognized style or tradition. A designed historic landscape has historical association with a significant person, trend, or movement in landscape gardening or architecture, or a significant relationship to the theory or practice of landscape architecture.

Doghair thickets: Young stands of equally aged trees (usually white fir, incense-cedar, and ponderosa pine) densely packed due to exclusion of natural and cultural fires. Such thickets are highly susceptible to insect outbreaks, diseases, wildfire, and mechanical damage from snow and wind.

Dry laid: Method of stone masonry in which rock structures are constructed without the use of mortar.

Drop inlet:A drop inlet is a mechanical system which lowers water through a box or pipe structure. This system internally dissipates most of the energy produced by the water.

Ecological restoration: Ecological restoration is the process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed.

Economy lodging: A type of overnight visitor lodging having basic amenities and offering the lowest-priced, hard-sided accommodations found in Yosemite National Park (rustic lodging with canvas roof and/or walls is priced lower). Economy lodging in Yosemite Valley can be found at Curry Village. As required by law, prices are established by the National Park Service after considering market forces and relevant factors as well as reviewing a sample of comparable facilities operated under similar conditions in California. Double occupancy prices for economy lodging in 1999 ranged from $45 - $75, plus tax, depending on room type and season.

Ecosystem: An ecosystem can be defined as a geographically identifiable area that encompasses unique physical and biological characteristics. It is the sum of the plant community, animal community, and environment in a particular region or habitat.

Ecotone: A transition zone between different habitat types, such as the area between meadows and California black oak woodlands.

El Portal Administrative Site: An area of federally owned land under National Park Service jurisdiction outside of Yosemite National Park and adjacent to the western park boundary along Highway 140. In 1958, the administrative site, including the community of El Portal, was designated by the U.S. Congress to be used for park operations, housing, and administration. See Vol. I C, plate 1-6.

Eluviation: The movement through the soil of materials brought into suspension or dissolved by the action of water.

Emergent wetland: A wetland characterized by frequent or continual inundation dominated by herbaceous species of plants typically rooted underwater and emerging into air (e.g., cattails, rushes), excluding mosses andlichens. This vegetation is present for most of the growing season in most years. Perennial plants usually dominate these wetlands. All water regimes are included, except sub-tidal and irregularly exposed.

Employee bed: See Bed.

Endangered species: See Threatened and endangered species.

End section: End sections are structures attached to the ends of culverts to control debris and water flow entering and exiting the pipe.

Energy dissipaters: A structure at a culvert outlet designed to dissipate the energy of water flow and direct the water to its natural channel.

Environmental Assessment: A public document required under the National Environmental Policy Act (NEPA) that identifies and analyzes activities that might affect the human and natural environment. An environmental assessment is a concise public document that: provides sufficient evidence and analysis for determining whether to prepare an Environmental Impact Statement (EIS), aids an agency’s compliance with NEPA when no EIS is necessary; and facilitates preparation of an EIS when one is necessary.

Environmental consequences: A section of an environmental impact statement that is the scientific and analytic basis for comparing alternatives. This discussion includes the environmental effects of the alternatives, any adverse effects that cannot be avoided, and short-term, long-term and cumulative effects. These environmental effects include ecological, aesthetic, historical, cultural, economic, and social (Bass and Herson 1993).

Environmental Impact Statement: A detailed statement required by the National Environmental Policy Act (NEPA) when an agency proposes a major action that significantly affects the quality of the human environment. This document describes and analyzes the activities that might affect the human environment (Bass and Herson 1993).

Environmental justice: Ensuring the rights of low-income people and communities of color to experience and enjoy clean and healthy environments. Executive Order 12898 requires that the National Park Service ensures that its programs, policies, and activities do not exclude, discriminate, or deny persons because of their race, color, or national origin.

Environmentally Preferable Alternative: The environmentally preferable alternative is the alternative within the range of alternatives presented in a Draft Environmental Impact Statement that best promotes the goals of the National Environmental Policy Act (NEPA). In general, this is the alternative causes the least damage to the environment and best protects natural and cultural resources. In practice, one alternative may be more preferable for some environmental resources while another alternative may be preferable for other resources.

Erratics: Rock fragments of any size carried by glacial or floating ice and deposited at some distance from the place of origin.

Exotic species: See Non-native species.

Facilities: Buildings and the associated supporting infrastructure such as roads, trails, and utilities.

Facultative wetland species: Plant species that can, but do not always, occur in wetlands. Facultative species indicate possible wetland conditions; further study of other wetland indicators (e.g., soils and inundation patterns) may be warranted.

Fell-field: A community of widely scattered dwarfed vegetation that grows in the barren land above the timberline.

Fen: A unique wetland type, possessing a water source that originates from alkaline ground water. Typically fens possess unique wetland vegetation adapted to saturated alkaline growing conditions.

Fire return interval: The typical period of time between naturally occurring fires. Fire return intervals vary by vegetation type and location.

Finding of No Significant Impact (FONSI): The public document describing the decision made on selecting the “preferred alternative” in an environmental assessment. See “environmental assessment.”

Floodplain: A nearly level alluvial plain that borders a river or stream and is subject to flooding unless protected artificially.

Fluvial: A term used to indicate the presence or interaction of a river within an area or landform.

Footprint: The land area covered or occupied by a function or structure.

Frazil ice: Stream ice with the consistency of slush, formed when small ice crystals develop in super-cooled stream water as air temperatures drop below freezing. These ice crystals join and are pressed together by newer crystals as they form.

Free-flowing river: A body of water existing or flowing under natural conditions without impoundments, diversions, straightening, riprapping, or other modification of the waterway (as defined in the Wild and Scenic Rivers Act - 16 USC 1286 [b]). Also see Riprap.

Fuel loads: The quantities of burnable, wildland fire fuels, normally expressed in tons per acre. The exclusion of natural and cultural fires has resulted in unnaturally high and hazardous fuel loads in many forested areas making management by prescribed fire unsafe.

Fuel/propulsion technology: The practical application of knowledge in the development of fuels, both petroleum and nonpetroleum, and the engineering of appropriate power and drive systems for vehicles.

Full build-out: The condition that occurs when all planned facilities are constructed; or the utilization of all suitable and designated locations within an area.

Geologic hazards: Natural geologic processes (i.e., rockfall) that occur or could potentially occur in locations that present a threat to humans or developed areas.

Geographic information system (GIS): A unique assemblage of hardware, software, and personnel that integrates digital databases, spatial technologies, and analytical methods in order to capture, store, edit, analyze, and display geographic data.

Geomorphic: Refers to the shape of the earth, or the shape of features on the earth’s surface.

Glaciation: A collective term for geologic processes of glacial activity, including erosion, deposition, and the resulting effects of such action on the earth’s surface.

Governing mandates: The National Park Service is directed to address user capacity, resource protection, and public enjoyment of park resources through a number of pieces of legislation such as laws, regulations, policies, and programs. These mandates establish the authority and responsibility for management in Yosemite National Park.

Groundwater: All water found below the surface of the ground. Also see Surface water.

Habitat fragmentation: The partitioning of larger habitats into smaller more isolated parcels, usually as a result of development. Fragmentation of habitat can negatively affect the abundance and diversity of plants and animals in an area.

Hazard trees: "...any tree...either alive or dead, which due to outwardly visible defects could fall down (in part or in entirety) and strike a person or property within any designated portion of a development zone." (WR-093)

Hazardous material: A substance or combination of substances that, because of quantity, concentration, or physical, chemical, or infectious characteristics, may either: (1) cause or significantly contribute to an increase in mortality or an increase in serious, irreversible, or incapacitating illness, or (2) pose a substantial present or potential hazard to human health or environment when improperly treated, stored, transported, used, or disposed of.

Hazardous waste: Hazardous materials that no longer have practical use, such as substances that have been discarded, spilled, or contaminated, or that are being temporarily stored prior to proper disposal.

Headwaters: The point or area of origin for a river or stream.

Headwall: A headwall is a supporting structure constructed at the end of a drainage structure such as a culvert.

Herbaceous: Refers to plants that lack a woody structure.

Highly valued resources: A set of natural and cultural resources that are the park’s highest priority for protection and restoration. Highly valued resources in Yosemite Valley, as are identified in the Yosemite Valley Plan, those that make up the Merced River ecosystem (Merced River, wetlands, riparian, and meadow communities), California black oak woodlands, sensitive wildlife habitat, rich soil areas, National Historic Landmarks, and important archeological sites. Highly valued resources are graphically portrayed in Vol. Ic, plate C.

Historic American Buildings Survey (HABS)/Historic American Engineering Record (HAER): An architectural and engineering documentation program that produces a thorough archival record of buildings, engineered structures, and cultural landscapes significant in American history and the growth and development of the built environment.

Historic character: The sum of all visual aspects, features, materials, and spaces associated with the historic nature of a site, structure, or landscape.

Historic district: A geographically definable urban or rural area, possessing a significant concentration, linkage, or continuity of sites, landscapes, structures, or objects united by past events or aesthetically by plan or physical developments. A district may also be composed of individual elements separated geographically but linked by association or history.

Historic topography: The physical features and contours of a place or region as they existed during historic time.

Hotel: A structure containing more than eighteen lodging rooms, as defined in the 1992 Concession Services Plan/EIS.

Housing actions: The component of alternatives that describes the potential locations, types, and numbers of employee housing. Also see Bed.

Housing support facilities: Amenities required by a typical residential community (i.e., post office, food preparation and service, recreational facilities, barber shop, child care, etc.).

Housekeeping unit: A type of rustic accommodation found within Housekeeping Camp in Yosemite Valley. The unit is composed of a concrete three-walled structure with canvas roof and door, a small patio, and a common bathroom. Also see Rustic accommodation.

Hydric soils: Soils that are characterized by an abundance of moisture, periodically producing anaerobic conditions.

Hydrodynamics: The flow, fluctuation, and character of water in a system.

Hydrogeomorphology: The science dealing with how the land is shaped by hydrological processes, such as the formation of the floodplain in Yosemite Valley and the channels of the Merced River.

Hydrologic response: The response of a watershed to precipitation, often the resulting streamflow from a precipitation event or snowmelt.

Hydrology: The science dealing with the properties, distribution, and circulation of water on the surface of the land, in the soil and underlying rocks, and in the atmosphere.

Hydromorphic classification: A wetland classification system that distinguishes wetland features based on position in the landscape, geomorphic setting, and hydrodynamics (National Research Council 1995).

Hydrophilic: Refers to soils that have an affinity for water, usually soils with high clay content.

Hydrophyte: Any plant growing in water or in a substrate that has an abundance of moisture. Hydrophytes are typically found in wetland habitats.

Illuviation: The accumulation in a soil layer of material that has been leached out of another layer.

Impacts: Effects, both beneficial and adverse, of an action on the human environment. Direct effects are those occurring at the same time and place as the action itself. Indirect effects occur later in time or are farther removed in distance from the action, yet are reasonably foreseeable.

IMPLAN: An economic impact assessment modeling system that allows the user to build economic models to estimate the impacts of economic changes.

Implementation plan: Implementation plans tier off of programmatic plans (like the General Management Plan) and focus on how to implement an activity or project needed to achieve a long-term goal. Implementation plans may direct specific projects as well as ongoing management activities or programs. They provide a more extensive level of detail and analysis than do general management plans. Implementation plans are required to undergo NEPA review.

Implementation project: Implementation projects are specific actions identified in an implementation plan.

Indicators: Indicators are specific elements of a system that provide information on the functioning of the system as a whole. Under the Visitor Experience and Resource Protection framework, indicators are specific and measurable physical, ecological, or social variables that reflect the overall condition of a zone or area caused by visitor use and/or visitor use related impacts. These indicators serve as early warning signs that too much use is occurring, or that the types of use are having an adverse affect on Outstandingly Remarkable Values. Resource indicators measure visitor impacts on the biological, physical and/or cultural resources of a park; social indicators measure impacts on the visitor experience.

Infrastructure: The various systems and facilities needed to support park operations and visitor services (e.g., sewer and water systems, electric systems, communication lines, roads and trails, and various support buildings).

Inlet: Where water enters a culvert or other drainage feature.

Inoculum: Refers to naturally occurring fungal material used to inoculate root systems.

Internal/external air pollution sources: Sources of air pollution either outside of a region or within a region; Yosemite Valley experiences air pollution from both sources: air pollution caused by motor vehicles within the Valley and air pollution originating in the San Joaquin Valley and moving into the Yosemite area.

Integrated utility corridor: An underground utility corridor that includes a high voltage and communications duct bank as well as a large diameter, high density, polyethylene pipe spare conduit for future use.

Krummholz: Krummholz is the name given to dwarfed and stunted trees that occupy environments characterized by intense solar radiation, high winds, excessive salts, and large diurnal temperature fluctuations.

Leq: See Average level (Leq).

Lacustrine: Of, or relating to lakes.

Ladder fuels: Flammable materials between the ground and tree canopy (a single tree or stand of trees) that provides an opportunity for a ground fire to ignite the canopy. Ladder fuels are typically composed of immature trees, shrubs, and dead or downed branches.

Lateral moraines: Linear moraines deposited along the sides of a glaciated valley. See Moraine.

Life zone: Bands of characteristic vegetation occurring along elevation gradients.

Lintel: Stone beams placed at the top of culverts to provide structural strength to a culvert headwall.

Liquefaction: A process by which water-saturated soils lose strength and liquefy during ground shaking events.

Lithic: Of or relating to stone or stone tools.

Lodging unit/room: Concessioner-operated facilities for overnight visitors. A lodging unit may be a single structure, such as a tent cabin, or a series of rooms grouped into larger motels or hotels. Lodging rooms in Yosemite are available at a range of prices that correspond to the type of structure as well as the amenities provided. See Cabin (lodging); Cottage; Hotel; Housekeeping unit; Motel. Also see Deluxe Lodging; Economy Lodging; Mid-scale Lodging; Rustic Lodging.

Management action: Actions taken by park management to protect river values and return conditions to established standards based upon information gathered by the Visitor Experience & Resource Protection monitoring program.

Mast crop: The fallen fruit of forest trees (such as acorns) used as forage by wildlife.

Mechanical treatment: The alteration of the landscape using hand implements, power tools, and heavy equipment.

Medial moraine: A deposit of glacial debris that indicates the point of contact between two glaciers moving in a parallel direction, combining their respective lateral moraines. See Moraine; Lateral moraines.

Microclimate: The distinct yet uniform, localized climate of a small site or habitat.

Mid-scale lodging: A type of overnight visitor lodging having a moderate number of amenities and, correspondingly, a price range located between deluxe and economy. In Yosemite Valley, mid-scale lodging rooms are located at Yosemite Lodge and Curry Village. As required by law, prices are established by the National Park Service after considering market forces and relevant factors as well as reviewing a sample of comparable facilities operated under similar conditions in California. Double occupancy prices for mid-scale lodging in 1999 ranged from $78 - $115, plus tax, depending on room type and season.

Mission 66 style (architecture): Refers to buildings developed in national parks between 1956 and 1966, during a period of experimentation with new structural forms, modern materials, and machine-driven methods of construction. The intent was to provide low maintenance, economical, permanent structures.

Mitigation: Activities that will avoid, reduce the severity of, or eliminate an adverse environmental impact. A mitigation measure should be a solution to an identified environmental problem.

Mixed conifer zone: Plant communities consisting of a mix of conifers such as pine, fir, incense-cedar, and Douglas-fir. The zone includes lower montane, montane, and upper montane coniferous forests. California black oak and other hardwoods are common associates.

Monoculture: The cultivation or growth of a single crop or organism to the exclusion of all others. Pervasive invading non-native plant species can sometimes create a near monoculture situation.

Montane: Of, relating to, or growing in the biogeographic zone of relatively moist cool upland slopes below the timberline, dominated by large coniferous trees.

Moraine: An accumulation of mineral material, such as boulders, stones, and sediment that is transported and deposited by a glacier.

Mosaic: A descriptive term for vegetation where the mix of species types and ages creates a diverse assemblage of vegetation or vegetation communities. This term can also be used to describe diversity in habitat types.

Motel: A structure containing more than eighteen lodging rooms, as defined in the 1992 Concession Services Plan/EIS.

Multi-use paved trail: A trail that is intended for pedestrian and bicycle use. Occasionally, short segments of multi-use trails may also be used for horses, maintenance, and emergency access by motor vehicles.

Museum collection: Objects, works of art, historic documents, and natural history specimens collected according to a rational scheme and maintained so they can be preserved, studied, and interpreted for public benefit.

NPS-Designated Roadside Parking: Roadside parking that the National Park Service has formalized either through pavement, gravel, and/or parking controls (e.g., berms, curbing, barrier stones, and fencing).

National Environmental Policy Act (NEPA): The federal act that requires the development of an Environmental Impact Statement for federal actions that might have substantial environmental, social, or other impacts.

National Historic Landmark: A district, site, building, structure, landscape, or object of national historical significance designated by the Secretary of the Interior under authority of the Historic Sites Act of 1935 and entered in the National Register of Historic Places.

National Park Service Management Policies: A policy is a guiding principle or procedure that sets the framework and provides direction for management decisions. National Park Service (NPS) policies are guided by and consistent with the Constitution, public laws, Executive proclamations and orders, and regulations and directives from higher authorities. Policies translate these sources of guidance into cohesive directions. Policy direction may be general or specific. It may prescribe the process by which decisions are made, how an action is to be accomplished, or the results are to be achieved. The primary source of National Park Service policy is the publication Management Policies 2006. The policies contained therein are applicable Service-wide. They reflect National Park Service management philosophy. Director's Orders supplement and may amend Management Policies. Unwritten or informal “policy” and people’s various understandings of National Park Service traditional practices are never relied on as official policy.

National Park Service Organic Act: In 1916, the National Park Service Organic Act established the National Park Service in order to “promote and regulate use of parks…” and defined the purpose of the national parks as “to conserve the scenery and natural and historic objects and wild life therein and to provide for the enjoyment of the same in a manner and by such means as will leave them unimpaired for the enjoyment of future generations.” This law provides overall guidance for the management of Yosemite National Park.

National Register of Historic Places: The comprehensive list of districts, sites, buildings, structures, and objects of national, regional, state, and local significance in American history, architecture, archeology, engineering, and culture. This list is maintained by the National Park Service under authority of the National Historic Preservation Act of 1966.

Natural quiet: The absence of human-caused sounds.

Natural processes: All processes such as hydrologic, geologic and ecosystemic, that are not the result of human manipulation.

Natural resources: Features and values that include plants and animals, water, air, soils, topographic features, geologic features, paleontologic resources, natural quiet, and clear night skies.

Natural topography: The natural shape or contour of the land.

No Action Alternative: The alternative in a plan that proposes to continue current management direction. "No action" means the proposed activity would not take place, and the environmental effects resulting from taking no action would be compared with the effects of permitting the proposed activity or an alternative activity to go forward.

Nonmotorized watercraft: A class of boats that includes rafts, kayaks, inner tubes, and inflatable air mattresses.

Non-native species: Species of plants or wildlife that are not native to a particular area and often interfere with natural biological systems.

Non-point sources: Pollutants that enter the environment from general noncontained locations. Examples of non-point sources are roadways, parking lots, and landscaped areas. Pollutants from these locations can include petrochemicals, heavy metals, and fertilizers.

Nonwilderness: Areas in Yosemite that have not been designated for special protection under the California Wilderness Act of 1984.

Obligate wetland species: Plant species that almost always occur in wetlands.

Off-season: Refers to a period of year when Yosemite visitation is lowest, usually from late autumn to early spring. Also see Peak season.

Ordinary high water: The area along the river corridor that would receive floodwaters during an ordinary precipitation year (based on a 2.33-year flood). A 2.33-year flood event has the probability of occurring roughly 50 percent of the time during any given year.

Outlet: Where water exits a culvert or other drainage feature.

Out-of-Valley: Not occurring in Yosemite Valley.

Out-of-Valley parking: Day-visitor parking outside of Yosemite Valley. Out-of-Valley parking refers to parking areas located either inside or outside the park boundary.

Outstandingly Remarkable Values (ORVs): As defined by the Wild and Scenic Rivers Act, those resources in the corridor of a Wild and Scenic River that are of special value and warrant protection. ORVs are the “scenic, recreational, geologic, fish and wildlife, historic, cultural or other similar values…that shall be protected for the benefit and enjoyment of present and future generations” (16 USC 1272).

Overnight visitor: Refers to visitors who spend the night in Yosemite Valley. This includes those that stay in lodging, campgrounds, and wilderness areas.

Overstory: The layer of foliage in a forest canopy.

Over-the-road coach: A bus designed for high-speed travel on highways with storage under the floor; a tour bus.

Oxbow: A bend in a meandering river channel that is abandoned as the river shifts its course over time. Oxbows can remain saturated with surface water or groundwater for some time, providing diverse wetland habitats for vegetation and wildlife.

Paleoenvironment: The environment that existed during some time in prehistory.

Palustrine: A term relating to vegetated wetlands (e.g., marsh, swamp, fen, bogs) and small, shallow ponds.

Park partner: An organization that maintains a formal agreement with the National Park Service to provide visitor services in conjunction with Yosemite National Park or otherwise assist the National Park Service; examples include the Yosemite Institute, Yosemite Association, Yosemite Fund, and the Sierra Club (operates LeConte Memorial Lodge).

Particulate matter (PM10 and PM2.5): Particles with diameters of 10 microns or less (PM10) or 2.5 microns or less (PM2.5). Such particles can be inhaled into the air passages and the lungs and can cause adverse health effects. High levels of PM2.5 are also associated with regional haze and visibility impairment.

Paved apron: A 4-foot wide paved swath which makes the transition from the paved roadway to an unpaved turnout.

Peak season: Refers to a period of the year when park visitation is highest: broadly speaking, this includes late spring, summer, and early fall. Also see Off-season.

Pedestrian/stock trail: Mostly unpaved trails intended to accommodate both pedestrians and stock users. (Use of bicycles on unpaved trails is prohibited.)

Permeable subgrade: A free draining layer of open-graded (of similar size) aggregate with high permeability, wrapped with a geotextile fabric, and placed between the base material of a roadbed and the native soils, designed to rapidly remove free water from most elements of pavement.

Planning: An interdisciplinary process for developing short-term and long-term goals for visitor experience, resource conditions, and facility placement.

Point bars: Areas along the inside bends of a meandering river where material is deposited.

Pool-riffle: The relationship, usually expressed as a ratio, between the surface area of pools and that of small rapids (riffles) in a given portion of a stream or river.

Post-flood conditions: Describes the environment in Yosemite Valley following the January 1997 flood. Post-flood conditions include any subsequent clean-up activities, such as the removal of flood-damaged facilities at Yosemite Lodge and the closure of Upper and Lower River Campgrounds.

Potential Wilderness additions: In Yosemite, these are areas that are officially designated as potential Wilderness additions under the California Wilderness Act of 1984. Potential Wilderness additions are managed as Wilderness until the time that they can be become designated Wilderness. Potential Wilderness additions can become Wilderness without further Congressional action if the use (e.g., roads and trails) or activity (e.g., motorized use) precluding Wilderness designation ceases.

Preferred Alternative: The preferred alternative is the alternative within the range of alternatives presented in an environmental assessment that the agency believes would best fulfill the purpose and need of the proposed action. While the preferred alternative is a different concept from the environmentally preferable alternative, they may also be one and the same for some environmental assessments.

Prescribed fire: Fires that are intentionally ignited under controlled conditions to meet management goals for natural resources and processes, wildland fire protection, and cultural resource preservation.

Preservation (cultural resource): The act or process of applying measures to sustain the existing form, integrity, and material of a historic structure, landscape, or object. Work may include preliminary measures to protect and stabilize the property, but generally focuses on the ongoing preservation, maintenance, and repair of historic materials and features rather than extensive replacement and new work.

Preservation (natural resource): The act or process of preventing, eliminating, or reducing impacts to natural resources and natural processes.

Programmatic accessibility: The ability for visitors with disabilities to participate in the range of programs offered in the park. This includes access to interpretive programs, concessioner services, scenic views, and audio-visual media.

Programmatic plan: Programmatic plans establish broad management direction for Yosemite National Park. The 1980 General Management Plan it a programmatic plan with a purpose to set a “clearly defined direction for resource preservation and visitor use” and provide general directions and policies to guide planning and management in the park. The 2005 Revised Merced River Plan is also a programmatic plan that guides future activities in the Merced River corridor. Programmatic plans are required to undergo NEPA review.

Protected species: See Threatened and endangered species.

Protohistoric: Refers to a time immediately before written history.

Public comment process: The public comment process is a formalized process required by the National Environmental Policy Act (NEPA) in which the National Park Service must publish a Notice Of Availability in the Federal Register which provides public notice that a Draft Environmental Impact Statement (EIS) and associated information, including scoping comments and supporting documentation, is available for public review and input pursuant to the Freedom Of Information Act. In addition, the National Park Service must conduct formal public hearings on the Draft EIS when required by statute or the Council on Environmental Quality NEPA Regulations.

Pulverization: See “Asphalt Pulverizing”

Radiating impacts: Human activity and associated foot traffic that originates in visitor focal points, such as parking lots, and spreads into adjacent areas.

Recessional moraines: A moraine or series of moraines deposited by glaciers as they retreat across a landscape. See Moraine.

Reconstruction: The act or process of depicting, by means of new work, the form, features, and detailing of a nonsurviving historic structure or landscape for the purpose of replicating its appearance at a specific time and in its historic location. (The term also refers to the resulting structure or landscape.)

Record of Decision (ROD): The public document following the preparation of an environmental impact statement that reflects the agency’s final decision, rationale behind the decision, and commitments to monitoring and mitigation.

Redevelop: A term that applies to areas that are currently developed, where all or part of the existing development is removed and replaced, modified, or adaptively reused.

Regional transit: A system that provides transportation to and from Yosemite Valley and other areas of the park from communities and locations outside of the park.

Rehabilitation (cultural resources): The act or process of making possible an efficient, compatible use for a historic structure or landscape through repair, alterations, and additions while preserving the portions or features which convey the historical, cultural, and architectural values. Also see Adaptive use.

Rehabilitation (natural resources): All activities conducted to improve the quality or biologic function of an impacted natural resource. The term rehabilitation connotes a less extensive process than restoration. Site impacts may preclude a full restoration, but project work is undertaken to enhance the extent or function of natural processes.

Resilient soil: Types of soil that can withstand certain levels of human impact (e.g., foot traffic) without changing its natural character and biological function.

Resilient ecosystem: Ecosystem types that have the ability to rebound from negative impacts to resources and natural processes with negligible or minimal long-term effects.

Restricted access: During periods of high traffic congestion, some vehicles may be required to wait to gain entry to Yosemite Valley (and sometimes the entire park) for portions of the day, with the exception of those visitors who have lodging or camping reservations.

Restricted Access Plan: The Restricted Access Plan lists the criteria and procedures for implementing restricted access. See Restricted access.

Restoration (cultural): The act or process of accurately depicting the form, features, and character of an existing historic structure, landscape, or object as it appeared at a particular period of time, by removing modern additions and replacing lost portions of historic fabric, paint, or other elements.

Restoration (natural): Work conducted to remove impacts to natural resources and restore natural processes, and to return a site to natural conditions.

Revegetation: Replacement or augmentation of native plants in an area largely or entirely denuded of vegetation.

Riffle: See Pool-riffle.

Riparian area: The land area and associated vegetation bordering a stream or river.

Riprap: A layer of large, durable fragments of broken rocks specially selected and graded, thrown together irregularly or fitted together to prevent water erosion.

River corridor: The area within the boundaries of a Wild and Scenic River (e.g., the Merced River corridor).

River Protection Overlay: The river and a buffer area adjacent to the river that allows for the protection and restoration of natural and aquatic ecosystem processes.

Riverine: Of or relating to a river. A riverine system includes all wetlands and deepwater habitats contained within a channel, with two exceptions: (1) wetlands dominated by trees, shrubs, persistent emergents, emergent mosses, or lichens, and (2) habitats with water containing ocean-derived salts in excess of 0.5%. A channel is an open conduit either naturally or artificially created which periodically or continuously contains moving water, or which forms a connecting link between two bodies of standing water.

Roadside parking: Locations along the Yosemite Valley Loop Roadway where vehicles have the ability to pull off roadway and are considered to be either “NPS-designated” or “User-designated.” Parking lots in the project area are not considered roadside parking in this environmental assessment.

Rockfall: Associated forms of mass movement such as rock avalanches, rockslides, debris slides, and debris flows (Wieczorek, et al. 1998).

Rockfall shadow zone (SL): A distance calculated to determine outlying boulder locations beyond the extent of talus. The SL is determined by a procedure based on the apex of the talus and a minimum shadow angle of 22 degrees (Wieczorek et al. 1998). It is graphically depicted in Vol. Ic, plate D.

Rockfall talus zone: See Talus slope zone.

Rustic lodging: The most economical lodging type provided in the park; rustic lodging has the fewest number of amenities. Most rustic lodging consists of canvas tents on wooden frames and are furnished with cots. Linen service and daily housekeeping are generally not provided. In Yosemite Valley, rustic lodging is provided at Curry Village and Housekeeping Camp. As required by law, prices are established by the National Park Service after considering market forces and relevant factors, as well as reviewing a sample of comparable facilities operated under similar conditions in California.

Rustic style (architecture): Refers to a building style developed in the 1920s and 1930s in national parks. The rustic style emphasized the use of natural materials and textures and thoughtful integration with the natural landscape.

Saprophytic: Obtaining food by absorbing dissolved organic material; saprophytic plants live on dead or decaying organic matter and assist in the breakdown of such into humus.

Scarification: A restoration term meaning the decompaction or loosening of topsoil to allow for enhanced vegetative growth and absorption of moisture.

Section 7 determination process: Section 7 of the Wild and Scenic Rivers Act specifies restrictions on hydro and water resources development projects. Water resources projects are subject to Section 7 of the Wild Scenic Rivers Act (16 USC 1278). Section 7(a) states, “no department or agency of the United States shall assist by loan, grant, license or otherwise in the construction of any water resources project that would have a direct and adverse effect on the values for which such river was established, as determined by the Secretary charged with its administration.”

Section 35: The area on the South Fork of the Merced River, originally designated by the U.S. Geological Survey, that demarcates the "township of Wawona" and contains intermixed parcels of private and National Park Service lands.

Sediment: A particle of soil or rock dislodged, transported, and deposited by surface runoff or a stream. The particle can range in size from microscopic to cobble stones.

Segment: Section 2 of the Wild and Scenic Rivers Act requires that the Merced River be classified and administered as “wild”, “scenic”, or “recreational” river segments, based on the condition of the river corridor at the time of boundary designation. The classification of a river segment indicates the level of development on the shorelines, the level of development in the watershed, and the accessibility by road or trail. “Wild” segments are free of impoundments and generally inaccessible except by trail, with watersheds and/or shorelines essentially primitive and unpolluted; “Scenic” segments are free of impoundments, with watersheds and shorelines largely undeveloped, but accessible in places by roads; and, “Recreational” segments are readily accessible by road or railroad, may have some development along the shorelines, and may have undergone impoundment or diversion in the past. The Merced River is divided into eight segments.

Segment Limits: Represents the maximum number of users that would be allowed in a segment of the Merced River corridor on any single day during peak visitor periods.

Sense of arrival: An emotional and mental state that accompanies the end of a visitor’s travels and the beginning of their park experience. For many visitors, arriving in Yosemite Valley marks the end of a considerable journey involving both lengthy planning and travel. For some, a sense of arrival is created by the clear opportunity to park their car, learn about and plan activities in the park, and begin their exploration of the park with the assistance of exhibits, signs, guidebooks, trails, shuttle buses, etc. For others, this sense of arrival begins with the first sight of Yosemite icons (e.g., Tunnel View, El Capitan, Half Dome). For returning visitors, this sense of arrival may occur as they check into their campsite, cabin, or lodging room.

Sheetflow: Flowing water that is not confined to a channel.

Shoulder season: The nonpeak park visitation season on either side of peak summer months. For example, the calendar months of April, May, September, and October are included in the shoulder season.

Site hardening: Any development that creates an impervious ground surface. Usually used as a way to direct visitor use and reduce impacts to resources.

Snag(s): Snags consist of dead trees that remain standing or leaning against another tree. Snags provide cavity habitats for a variety of wildlife species. Snags near trails or camping areas represent hazards which must be managed or removed.

Social trails: A social trail is an informal, non-designated trail between two locations. Social trails often result in trampling stresses to sensitive vegetation types.

Special Use Occupancy: Designation for structures or facilities that can have more than 300 people present at one time.

Standards: Standards are the minimum acceptable conditions established for VERP indicators. They identify when management action should be taken to reduce or reverse visitor-use related impacts. A standard does not define an intolerable condition nor is it a condition that managers should strive to achieve, unless intolerable conditions already exist.

Statement of Finding (SOF): As it refers to floodplains, a document normally associated with an environmental impact statement or environmental assessment that explains why an action is to be taken in a regulatory floodplain. The SOF describes the risk associated with use of the regulatory floodplain and how mitigation of flood risk would be achieved. (See Appendix N.)

Stewardship: The responsibility of caring for the park. This often grows from an understanding of and respect for the principles of the National Park System and the needs of the park’s natural, social, and cultural environment.

Stock: This term generally refers to horses and mules used for riding or carrying packed supplies on established trails.

Succession: The process by which vegetation is either re-established following a disturbance or by which it initially develops in an unvegetated site. This term also refers to the entire process from initial colonization to the development of vegetation typical of that geographic area.

Superelevation: The slope or incline of a roadway cross-section that aides in curve negotiation (typically greater than 2%).

Surface water: Water that naturally flows or settles on top of natural landforms and vegetation, often as rivers, streams, lakes, ponds, and other bodies of water.

Talus: An accumulated mass of rock fragments (broken rock formed by falling, rolling, or sliding) of various sizes derived from and lying at the base of a steep slope (Wieczorek, et al. 1998).

Talus slope zone (TS): The area where the majority of accumulated rock debris is deposited at the base of a steep slope following a mass movement event (i.e., rockfall) (Wieczorek, et al. 1998). It is graphically depicted in Vol. Ic, plate D.

Tarn: A small, mountain lake or pool.

Terminal moraine: Ridges of material deposited at the terminus of a glacier. See Moraine.

Terrestrial: Living on or growing from land.

Threatened and Endangered Species: Species of plants that receive special protection under state and/or federal laws. Also referred to as “listed species” or “endangered species.”

Traditional cultural resource: Any site, structure, object, landscape, or natural resource feature assigned traditional, legendary, religious, subsistence, or other significance in the cultural system of a group traditionally associated with it.

Traditional cultural properties: Traditional cultural resources that are eligible for or listed on the National Register of Historic Places as historic properties.

Traffic check station: A location where vehicle access is regulated; typically requires buildings, multiple traffic lanes, and staffing.

Transit bus: A mode of transportation that operates on a schedule along routes with established stops. Transit buses do not require daytime parking in Yosemite Valley, as they continuously pick up and drop off passengers along their established routes.

Treatment: Work carried out to achieve a historic preservation goal. The four primary treatments are Preservation, Rehabilitation, Restoration, and Reconstruction (as stated in Secretary of Interior’s Standards for the Treatment of Historic Properties).

Umacha: A Miwok structure made of cedar bark and used for shelter.

Understory: An underlying layer of vegetation, specifically the vegetative layer, and especially the trees and shrubs, between the forest canopy and the ground cover.

Ungulates: Hoofed herbivores, e.g., mule deer.

Upland community: The vegetation found where soil conditions are average to dry and where soils are only infrequently flooded or saturated. In Yosemite Valley, mixed conifer, California black oak, and live oak communities dominate uplands.

User capacity: As it applies to parks, user capacity is the type and level of use that can be accommodated while sustaining the desired resource and social conditions based on the purpose and objectives of a park unit.

User-designated roadside parking: Roadside parking that has been established over time through visitor use; these locations are not necessarily encouraged or discouraged by the National Park Service. These locations are not considered to be “formalized” through the use of pavement, gravel and/or parking controls.

User groups: Park visitors who participate in any one activity are considered members of a user group. An individual may belong to a number of different user groups. User groups may desire different, and sometimes conflicting, experiences in the same area (e.g., fishing and swimming in the same stretch of river).

Visitor experience: The perceptions, feelings, and reactions a park visitor has in relationship with the surrounding environment.

Visitor Experience and Resource Protection (VERP): A user capacity method developed for the National Park Service to measure and manage the impacts of use on the visitor experience and the resource conditions in national parks. VERP is an ongoing, iterative system that measures the type, level and location of visitor use that can be accommodated while sustaining the desired resource and social conditions that complement the purposes of the park units and their management objectives. The VERP framework contains nine elements, four of which are key to developing a user capacity program. The VERP user capacity model establishes (1) a management zoning designation, (2) indicators or measurable variables that reflect the overall condition of a zone, (3) standards that set the basis for judging whether or not conditions are being met, and (4) management actions that must be take if monitoring reveals that conditions are not within standard.

Visitor use: Refers to the types of recreation activities visitors participate in, numbers of people in an area, their behavior, the timing of use, and distribution of use within a given area.

Walk-in campground: A campground with consolidated parking areas separated from the individual campsites. Campers walk a short distance from the parking area to their campsites (e.g., Camp 4 [Sunnyside Campground]).

Walk-to campground: A campground with no parking at the campsite, and no designated parking place associated with the campground. These campgrounds would be available for campers arriving in Yosemite Valley without a private vehicle (i.e., by bus, on foot, by bicycle).

Watershed:The region draining into a river, river system, or body of water.

Wetland: Wetlands are defined by the U.S. Army Corps of Engineers (CFR, Section 328.3[b], 1986) as those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions.

White pine blister rust: A non-native disease affecting five-needled pines including sugar pine and also shrubs in the genus Ribes (alternate host). Extensive prevention and control efforts in the 1930s focused on eradication of Ribes bushes. These efforts resulted in the creation of several small settlements to house the thousands of people hired by the government for this work project.

Wilderness: Areas protected by provisions of the Wilderness Act of 1964. These areas are characterized by a lack of human interference in natural processes; generally, there are no roads, structures, installations, and the use of motorized equipment is not allowed.

Wild and Scenic River: A river receiving special protection under the Wild and Scenic Rivers Act. Both the Merced and Tuolumne Rivers are Wild and Scenic Rivers within the park.

Wingwalls: Extended walls constructed at an oblique angle at the ends of a culvert. Wing walls help protect culvert headwalls, and channel water efficiently through inlets and outlets.