Yosemite Valley Plan SEIS, Volume IB Part 2, Glossary

GLOSSARY

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 level (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: The existing biological, physical, cultural, social, and economic conditions that are subject to both direct and indirect changes as a result of actions described within alternatives under consideration.

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: A reasonable range of options that can accomplish an agency’s objectives.

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: A root disease caused by a widespread native fungus (Heterobasidion annosum). In pines, the fungus spreads through the root system, attacking the inner bark and sapwood. Two to six years after initial infection, the fungus reaches the root crown and girdles the tree, but remains active as a wood-decaying organism within the roots and trunk of the dying tree. Pines weakened by annosus root disease are often killed by bark beetles. Incense-cedars, however, are not affected by bark beetles and will stand green for many years until the disease so weakens the trees that they fall down. Cedars are thought to act as a reservoir for annosus root disease because they take so long to die from the disease.

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.

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.

Average level (L_eq): 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.

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.

Best Management Practices: 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. Best Management Practices 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.

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: The President’s Council on Environmental Quality (CEQ) was established by the National Environmental Policy Act (NEPA). The council’s mission is to oversee and develop national environmental policy.

Choosing by Advantages: A decision-making process used as part of developing the Yosemite Valley Plan 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 Yosemite Concession Services. 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, sites, buildings, structures, objects, or cultural practices that are usually greater than 50 years of age and possess architectural, historic, scientific, or other technical value. By their nature, cultural resources are non-renewable.

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.

dBA: See decibel (dBA)

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.

Ecological restoration: See Restoration (natural).

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: A system that involves the interaction of organisms with their physical environment.

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 surface water inundation, dominated by herbaceous plant species rooted underwater and emerging into air (e.g., cattails, rushes).

Employee bed: See Bed.

Endangered species: See Threatened and endangered species.

Energy equivalent: See Average level (L_eq).

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.

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: Refers to buildings, houses, campgrounds, picnic areas, visitor-use areas, operational areas, and 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.

Floodplain: Land on either side of a stream or river that is submerged during floods.

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; 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.

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.

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 are 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.

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).

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.

Interpretation: Programs that support the mission of the National Park Service by assisting people in understanding, enjoying, and contributing to the protection of the park’s natural, cultural, and scenic resources and dynamic processes. Interpretive programs include walks and evening programs, guided tours, formal education programs for school groups, exhibits, audio-visual productions, and publications. In Yosemite, these programs are provided by the National Park Service and park partners, including Yosemite Concession Services, the Yosemite Association, The Ansel Adams Gallery, the Yosemite Institute, and the Sierra Club.

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

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.

L_eq: See Average level (L_eq).

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.

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.

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: An activity designed to avoid, minimize, rectify, eliminate, or compensate for impacts of a proposed project. 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.

National Environmental Policy Act (NEPA): The federal act that requires the development of an environmental impact statement (EIS) 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 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 process: A collective term for processes, including hydrologic, geologic, biologic, 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: An alternative in an environmental impact statement that continues current management direction. A no action alternative is a benchmark against which action alternatives are compared.

Non-native species: Species of plants or animals that do not naturally occur in a particular area and often interfere with natural biological systems. Also known as alien, introduced, or exotic species.

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).

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): The exceptional values of a river that warranted its inclusion in the national Wild and Scenic Rivers System. 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."

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 PM_2.5): Particles with diameters of 10 microns or less (PM₁₀) or 2.5 microns or less (PM_2.5). Such particles can be inhaled into the air passages and the lungs and can cause adverse health effects. High levels of PM_2.5 are also associated with regional haze and visibility impairment.

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.)

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.

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.

Protected species: See Threatened and endangered species.

Protohistoric: Refers to a time immediately before written history.

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 areas: Areas that are on or adjacent to rivers and streams; these areas are typically rich in biological diversity (flora and fauna).

Riprap: Any hardening of a shoreline (with rocks or cement) to stabilize river banks for the protection of facilities on or near the bank.

Riverine: Of or relating to a river. A riverine system includes all wetlands and deepwater habitats contained within a river channel.

River Protection Overlay (RPO): A buffer area intended to protect the Merced River within the park boundary and the El Portal Administrative site, as prescribed by the 2000 Draft Merced Wild and Scenic River Comprehensive Management Plan/Environmental Impact Statement. The River Protection Overlay includes the river channel and extends outward 150 feet from the ordinary high water line above 3,800 feet elevation (including Yosemite Valley and Wawona), and 100 feet from the ordinary high water line below 3,800 feet (including El Portal). It is graphically depicted in Vol. Ic, plates F-1 to F-3.

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. Double occupancy prices for rustic lodging in 1999 ranged from $40 - $46, plus tax, depending on room type and season.

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 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.

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.

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, nondesignated 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.

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.

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 and animals that receive special protection under state and federal laws. Also referred to as listed, endangered, or protected species.

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.

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 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 interaction a park visitor has in relationship with the environment. Within the context of the proposed alternatives, the Visitor Experience section describes general access, facilities, visitor services, interpretation and orientation, and recreational opportunities. Other elements also contribute to the quality of the visitor experience, such as the condition of natural and cultural resources, air quality, transportation, and noise.

Visitor Experience Resource Protection (VERP): A process developed for the National Park Service to help manage the impacts of visitor use on the visitor experiences and resource conditions in national parks.

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: Areas that are inundated by surface or groundwater with a frequency sufficient to support, under normal circumstances, vegetation or aquatic life that requires saturated or seasonally saturated soil conditions for growth and reproduction.

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.

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