Scenic integrityThe degree of "intactness" of a landscape, which is related to the existing amount of visual disturbance present.
Scenic qualityA measure of the intrinsic beauty of landform, water form, or vegetation in the landscape, as well as any visible human additions or alterations to the…
Scenic resourcesThe visible physical features on a landscape (e.g., land, water, vegetation, animals, structures, and other features).
Scenic valueThe importance of a landscape based on human perception of the intrinsic beauty of landform, water form, and vegetation in the landscape, as well as any…
SchistA metamorphic rock formed from many types of rocks. Minerals in the rocks include micas, chlorite, talc, hornblende, and garnets.
ScopingA first step in the NEPA process and in the river planning process. Scoping is a means of identifying issues and concerns, their significance, and the…
ScoriaCongealed lava, usually of mafic composition and red or black in color, with a large number of vesicles formed by gases coming out of solution.
ScraperA stone tool that is modified for the specific task of scraping; for example, to scrape the meat from hides, to remove fat from the underside of a skin…
ScreeSmall, loose, rock debris covering a slope; a slope of loose rock debris at the base of a steep incline or cliff.
screen analysisMethod for measuring a proportion of variously sized particles in solid fuels. The sample is passed through a series of screens of known size openings.
ScrubberA device to clean combustible gas or stack gas by the spraying of water.
ScrublandAn area of land that is uncultivated and covered with sparse stunted vegetation.
Second growthA second generation of timber of merchantable age.
Secondary containmentA safeguarding method for the prevention of unauthorized releases of toxic or hazardous gases into uncontrolled work areas.
Secondary successionThe progression of plant communities following disturbances such as fire, windthrow and timber harvesting. See Succession.
SedentismA term used to describe the process of settling down to live in groups for periods of time.
SedgeA grasslike plant with a triangular stem often growing in wet areas.
Sedimentary rockRock formed at or near the Earth's surface from the consolidation of loose sediment that has accumulated in layers through deposition by water, wind, or…
SedimentationA process in which material carried in suspension by water flows into streams and rivers, increasing turbidity and eventually settling to the bottom.
SeepageThe act or process involving the slow movement of water or other fluid through a porous material such as soil or rock.
SeepsWet areas, normally not flowing, arising from an underground water source. Any place where liquid has oozed from the ground to the surface.
SeismicPertaining to any earth vibration, especially that of an earthquake.
SeismicityRefers to the geographic and historical distribution of earthquakes.
Selection cuttingThe periodic removal at short intervals of the oldest and largest trees in the stand, individually or in small groups.
Semi-aridModerately dry region or climate where moisture is normally greater than under arid conditions but still definitely limits the production of vegetation.
SemiconductorAny material that has a limited capacity for conducting an electric current. Certain semiconductors, including silicon, gallium arsenide, copper indium…
Senior water rightsWater rights that have been established first (measured by the date of appropriation) to the limit of their respective right, frequently to the exclusion…
Sensitivity level (analysis)Measures (e.g., high, medium, and low) of public concern for the maintenance of scenic quality.
Seral stagesThe series of relatively transitory plant communities that develop during ecological succession from bare ground to the climax stage.
SewageThe waste water from domestic, commercial and industrial sources carried by sewers.
Shadow zoneThe region where direct sound does not penetrate because of upward diffraction due to vertical temperature and/or wind gradients.
Shaft horsepowerA measure of the actual mechanical energy per unit time delivered to a turning shaft. 1 shaft horsepower = 1 electric horsepower = 550 ft-lb/second.
Shale (outcrop)A fine-grained sedimentary rock characterized by parallel layering.
Shear strengthInternal resistance to stress (or movement) that comes from friction and cohesion of the sediment.
Short rotation intensive cultureIntensive management and harvesting at 2 to 10 year intervals of cycles of specially selected fast- growing hardwood species for the purpose of producing…
Short Ton2000 pounds. A ton, as commonly used in the U.S. and Canada.
Shrink-swell potentialThe extent to which soil shrinks or swells with changes in soil moisture content.
ShrubA plant with persistent woody stems and relatively low growth form; usually produces several basal shoots as opposed to a single bole; differs from a tree…
Shrub-steppeHabitat primarily composed of various shrubs and grasses.
Shrubsteppe obligateA species that is dependent on shrubsteppe habitats to provide food and/or habitat necessary for its survival.
SilencerA device used for reducing noise within air and gas flow systems.
Silicic volcanismVolcanism characterized by the eruption of magma that is rich in lighter elements such as silicon, oxygen, aluminum, sodium, and potassium.
SiliconA chemical element, of atomic number 14, that is semi-metallic, and an excellent semiconductor material used in solar photovoltaic devices; commonly found…
SiltA rock or mineral fragment of any composition that has a diameter ranging from 0.002 to 0.05 millimeter.
SiltationProcess by which loose soil is transferred and builds up in streams, rivers, and lakes, causing changes in stream channels and in depth.
SiltstoneA sedimentary rock made mostly of silt-sized grains.
SilvicultureThe theory and practice of forest stand establishment and management.
SinkAny process, activity, or mechanism which removes a greenhouse gas, an aerosol, or a precursor of a greenhouse gas or aerosol from the atmosphere.
Site potential treeA tree that has attained the average maximum height possible given site conditions where it occurs.
Site preparationVarious treatments applied to a harvested area to promote regeneration of the site.
SkidderA self-propelled machine to transport harvested trees or logs from the stump area to the landing or work deck.
Skirt (fan, dune)A sloping alluvial fan surface made of sediment deposited by a stream at the mouth of a canyon between a mountain and the adjacent alluvial valley floor.
Sky glowBrightening of the sky caused by outdoor lighting and natural atmospheric and celestial factors.
SkyliningSiting of a structure on or near a ridge line so that it is silhouetted against the sky.
SlashThe unmerchantable material left on site subsequent to harvesting a timber stand, including tops, limbs, cull sections.
Slip rateThe rate of motion obtained when the amount of offset is divided by a time interval.
Slope failureThe downward and outward movement of a mass of rock or unconsolidated materials as a unit. Landslides and slumps are examples.
Slope stabilityThe resistance of an inclined surface to failure by sliding or collapsing.
Slow pyrolysisThermal conversion of biomass to fuel by slow heating to less than 450°C in the absence of oxygen.
SludgeThe mixture of organic and inorganic substances separated from sewage.
Small Scale Energy Loan Program (SELP)(SELP)In Oregon, a low-cost loan and technical assistance program administered by the Oregon Department of Energy.
SmogA visible haze caused by particulate matter and ground-level ozone.
SnagAny standing dead, partially dead or defective tree. A hard snag is composed primarily of sound wood.
Social disruptionSocial and psychological dislocation associated with the alteration or breakdown of social life in small rural communities that may occur as a result of…
SocioeconomicRelating to social or economic factors or to a combination of both social and economic factors.
SocioeconomicsThe social and economic conditions in the study area.
softwoodGenerally, one of the botanical groups of trees that in most cases have needle-like or scale-like leaves; the conifers; also the wood produced by such…
Soil compactionCompression of the soil which results in reduced soil pore space (the spaces between soil particles), decreased movement of water and air into and within…
Soil depositionA general term for the accumulation of sediments by either physical or chemical sedimentation.
Soil horizonA layer of soil developed in response to localized chemical and physical processes resulting from the activities of soil organisms, the addition of…
Soil horizon mixingSoil horizon mixing occurs when soil is disturbed by activities such as excavation.
Solar ArrayA group of solar collectors or solar modules connected together.
Solar CellA solar photovoltaic device with a specified area.
Solar CollectorA device used to collect, absorb, and transfer solar energy to a working fluid.
Solar collector arrayThat portion of the solar energy facility containing components that track and capture sunlight and convert it to other useful forms of energy, typically…
Solar energyElectromagnetic energy transmitted from the sun (solar radiation). The amount that reaches the earth is equal to one billionth of total solar energy…
Solar energy technologyAny engineered method for harnessing, storing, and using the Sun's energy.
Solar Energy Zone (SEZ)(SEZ)Lands identified by the BLM as best-suited for large-scale production of solar energy.
Solar trackingThe solar panels can be swiveled using the electric motors to follow the path of the sun exactly in the course of the day to maximize the yields.
Sole source aquiferAn aquifer that supplies 50 percent or more of the drinking water of an area.
Solid wasteAll unwanted, abandoned, or discarded solid or semisolid material whether or not subject to decomposition, originating from any source.
SourceAny place or object from which air pollutants are released. Sources that are fixed in space are stationary sources and sources that move are mobile…
Southwest Regional Gap Analysis Project (SWReGAP)(SWReGAP)The Southwest Regional Gap Analysis Project is an update of the Gap Analysis Program's mapping and assessment of biodiversity for the five-state region…
Spawning gravelSorted, clean gravel patches of a size appropriate for the needs of resident or anadromous fish.
Special areasAreas of high public interest and containing outstanding natural features or values.
Special Use Airspace (SUA)(SUA)Airspace of defined dimensions identified by an area on the surface of the Earth wherein activities must be confined because of their nature and/or…
Specially Designated AreasIncludes a variety of areas that have received recognition or designation because they possess unique or important resource values.