Glossary of Terms

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


  • ADMA- Aquatic Diversity Management Area*
  • ALSE- Area of Late Successional Emphasis*
  • ASQ- Allowable sale quantity
  • AMS- Analysis of the Management Situation
  • AUM- Animal unit month*

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  • BA - Biological Assessment
  • BE- Biological Evaluation
  • BLM- Bureau of Land Management
  • BMP- Best Management Practices*
  • BMPEP- Best Management Practices Evaluation Process
  • BSS- Base sale schedule

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  • CALVEG- California Vegetation Classification System*
  • CASPO- California Spotted Owl Interim Guidelines*
  • CDF- California Division of Forestry
  • CEA- Cumulative effects analysis
  • CEQ- Council on Environmental Quality
  • CFR- Code of Federal Regulations
  • CMAI- Culmination of mean annual increment
  • CWAP- Clean Water Action Plan
  • CWHR- California Wildlife Habitat Relationships Program

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  • DBH- Diameter at breast height*
  • DEIS- Draft Environmental Impact Statement for the Herger-Feinstein Quincy Library Group Forest Recovery Act
  • DFPZ- Defensible fuel profile zone*

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  • EAEnvironmental Assessment
  • EBNFFR- East Branch North Fork Feather River
  • E/C- Energy/community zone
  • EFFALT- Effective alteration*
  • EIC- Ending inventory constraintEISEnvironmental Impact Statement
  • EPA- United States Environmental Protection Agency
  • ERA- Equivalent roaded acresEVCExisting visual condition

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  • FD- Forest Development System Road
  • FEIS- Final Environmental Impact Statement
  • FERC- Federal Energy Regulatory Commission
  • FRCMG- Feather River Resource Management Group
  • FSH- Forest Service Handbook
  • FSM- Forest Service Manual
  • FVS- Forest Vegetation Simulator
  • FY- Fiscal Year

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  • GIS- Geographic Information System
  • GMA- Goshawk Management Area*
  • HCA- Habitat Conservation Area
  • HCM- Habitat Capability Model
  • HMA- Habitat Management Area*

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  • IPM- Intergrated Pest Management
  • ISC- Interagency Spotted Owl Committee

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  • KV - Knutson-Vandenberg Act

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  • LRMP- Land and Resource Management Plan
  • LS/OG- Late successional /old growth
  • LTSYC- Long-term sustained yield capacity
  • LWD- Large woody debris

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  • MBF- Thousand board feet
  • MCF- Thousand cubic feet
  • MIR- Minimum implementation requirements
  • MIS- Management indicator species
  • MMBF- Million board feet
  • MMCF- Million cubic feet
  • MMR- Minimum management requirements

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  • NEPA- National Environmental Policy Act*
  • NFMA- National Forest Management Act
  • NFS- National Forest System lands
  • NOI- Notice of Intent
  • NNL- National Natural Landmark
  • NRCS- National Resource Conservation Service (formerly SCS – Soil Conservation Service)
  • NTU- Nephelometric turbidity units

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  • ODT- Oven dry tons
  • OHV- Off-highway vehicle
  • ORNL- Oak Ridge National Laboratory
  • ORV- Off-road vehicle

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  • PAC- Protected activity center
  • PACFISH- Interim Strategies for Managing Anadromous Fish
  • PCT- Pacific Crest Trail
  • PNV- Present net value

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  • QLG - Quincy Library Group

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  • Rare II- Roadless Area Review and Evaluation
  • RHCA- Riparian habitat conservation areas*
  • RIMR-Recreation Information Management
  • ROD- Record of Decision
  • RNA- Research Natural Area
  • RPA- Forest and Rangeland Renewable Resources Planning Act
  • RPZ- Riparian protection zoneRx Prescription

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  • SAT- Scientific Analysis Team guidelines for riparian protection
  • SIA- Special Interest Area
  • SMZ- Streamside management zone*
  • SNCF- Sierra Nevada Conservation Framework
  • SNEP- Sierra Nevada Ecosystem Project*
  • SOHA- Spotted Owl Habitat Area*
  • SPM- Semi-primitive, motorized
  • SPNM- Semi-primitive, non-motorized
  • SVS- Stand visualization simulator

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  • TES- Threatened and endangered species
  • TOC- Threshold of concern*
  • TSI- Timber stand improvement
  • TSP- Total suspended particulates

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  • USDA - United States Department of Agriculture
  • USDI - United States Department of Interior
  • USGS - United States Geological Survey
  • USC- United States Code
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  • VAC- Visual absorption capability
  • VIS- Visitor information services
  • VMS- Visual Management System
  • VQO- Visual quality objectives

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  • WFHR- Wildlife and Fish Habitat Relationships
  • WFUD- Wildlife and fish user day

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The glossary provides definitions of technical terms used in the FEIS and Lassen, Plumas, and Tahoe Forest Plans. A definition followed by (N) is a national-level Forest Service definition.

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Act: The Herger-Feinstein Quincy Library Group Forest Recovery Act of October 12, 1998.

Adaptive Management: A dynamic approach to forest management, in which the effects of treatments and decisions are continually monitored and used, along with research results, to modify management on a continuing basis to ensure that objectives are met.

Aerial Fuels: The fuels above the ground that are available to burn. Both small diameter trees and larger trees are considered aerial fuels in this analysis.

Affected Environment: The physical, biological, social, and economic environment where human activity is proposed.

Age Class: One of the intervals, usually 10 to 20 years, into which the age range of vegetation is divided for classification or use.

Allocation: The assignment of sets of management practices to particular land areas to achieve goals and objectives of the alternative.

Allotments: Specific areas in which authorized permittees are allowed to graze cattle, as specified by specific terms and conditions of a grazing permit.

Alternative: In forest planning, a given combination of resource uses and mix of management practices that achieve a desired management direction, goal, or emphasis.

Ameliorate: To improve or become more satisfactory.

Anadromous: Fish that spend part of their life cycle in salt water; for example, salmonids.

Aquatic Diversity Management Area: A watershed refuge that is (a) crucial to at-risk aquatic species, (b) contains intact native communities, and (c) is important to water quality.

Aquatic Ecosystems: The stream channel, lake, or estuary bed, water, biotic communities, and habitat features that occur therein.

Area Fuel Treatment: Area fuel treatments vary in size. Dead and live fuels are treated to reduce fire hazard. Area fuel treatments are arranged in a pattern that would reduce the burn intensity in the direction a fire is likely to spread. In broken terrain topography, they generally would be located on the upper portions of the southerly slope, but may also extend to the base of a slope. Design criteria for area fuel treatments vary between alternatives and can be found in Appendix J, Tables 2 and 3.

Area of Influence: A delineated geographic area in which the present or proposed actions of a forest unit exert an important influence on residents and visitors.

Area of Late Successional Emphasis (ALSE): The Sierra Nevada Ecosystem Project (SNEP) developed this strategy primarily for west side vegetation types of the Sierra Nevada range. Where possible, large areas (greater than 20,000 acres) that have a high percentage of late successional old growth (ranks 4 and 5) are delineated into areas of late successional emphasis. Areas of late successional emphasis are managed for old forest objectives. Reference the Sierra Nevada Ecosystem Project Report to Congress, Volume 1, page 101 for additional details.

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Basal Area: As it pertains to silviculture, this is a measure in square feet per acre of the surface area of a stand that is occupied by the boles (stems) of trees.

Best Management Practices (BMP): United States Environmental Protection Agency and State of California approved management practices designed to protect, maintain, or improve water quality by preventative rather than corrective means.

Biodiversity: The distribution and abundance of different plant and animal communities and species, habitats, seral stages, and special habitat components in an ecosystem.

Biomass Removal: The removal of a volume of living organic material. This term is usually refers to forest products that are not sawlog (for example, wood chips for mulch).

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California Spotted Owl Interim Direction (CASPO or CASPO Interim Guidelines): Refers to interim direction for the protection of California spotted owl, effective January 1993. Reference the California Spotted Owl Sierran Province Interim Guidelines Environmental Assessment, January 1993, the Decision Notice and Finding of No Significant Impact for California Spotted Owl Sierran Province Interim Guidelines, January 1993.

California Spotted Owl Protected Activity Center: A 300-acre, protected area in which California spotted owls find suitable nesting sites and several suitable roosts, and in which they carry out at least half of their nighttime foraging during the breeding season

California Vegetation Classification System (CALVEG): A State of California, Statewide classification system developed by the Forest Service for classifying vegetation and non-vegetation cover types. Reference Appendix B for additional details.

California Wildlife Habitat Relationships System (CWHR): The California Wildlife Habitat Relationships System includes habitat relationships models for over 600 wildlife species in the State of California. The system was designed as a planning tool to predict wildlife species communities, habitat suitability, and differences in habitat values between two situations for geographic locations and habitats in California. The system provides species habitat suitability ratings for feeding, cover, and foraging in varying habitat types and seral stages. These suitability ratings are converted to numeric values, and the three values are averaged to calculate overall habitat values for each habitat type and seral stage, for particular species. The California Wildlife Habitat Relationships System can be used to predict differences in habitat values between two habitat conditions, and can indicate which species may be negatively or positively affected, based on differences in habitat values between the two habitat conditions.

Canopy Closure: The degree to which the canopy (forest layers above one’s head) blocks sunlight or obscure the sky.

Compliance: As stated in the Act, “All required ‘Resource Management Activities’ shall be implemented to the extent consistent with applicable Federal law and standards and guidelines for the conservation of the California spotted owl, as set forth in the California Spotted Owl Sierran Province Interim Guidelines or subsequently issued guidelines.”

Continuity: The state or quality of being continuous, connected, or whole.

Crown Fire: A fire burning into the crown (leafy portion) of vegetation (particularly trees), generally associated with an intense understory fire.

Cumulative Effects: Changes as a result of more than one action that may enhance or degrade a specific site.

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Decommission: To permanently terminate the function of a road and mitigate any adverse impacts to forest resources in the process. Activities include blocking the entrance, assuring natural or artificial revegetation, removal of drainage structures, and re-establishing natural drainage-ways; and for Forest Development Roads, removal from the Forest Development Road inventory. Other activities may include water barring, pulling back unstable road shoulders, scattering woody material on the roadbed, mulching, treatment of intersections such that they are not apparent from remaining roads and to discourage continued use, tilling or other activities to reduce soil compaction, and recontouring slopes.

Road decommissioning may also include obliteration, where the road site is restored to near-natural contours, and natural revegetation is encouraged. If determined to be necessary through interdisciplinary team analysis, the site may be revegetated using native species. Periodic inspections for satisfactory recovery of the natural hydrologic function of the site are performed.

Defensible Fuel Profile Zone: Defensible fuel profile zones are approximately ¼ to ½ mile wide areas where fuel loadings are reduced. They usually are constructed along roads so as to break up fuel continuity across the landscape and provide a defensible zone for suppression forces. The edges of defensible fuel profile zones blend into adjacent forested areas. Design criteria are further described in Appendix J, Tables 1 and 2.

Diameter Breast Height (DBH): A measure of the cross-section size of a tree. Diameter of the tree bole is measured at a height of 42 inches above the ground (as measured at the highest ground level if the tree is on a slope).

Draft Environmental Impact Statement: The statement of environmental effects required for major Federal actions under Section 102 of the National Environmental Policy Act (NEPA), and released to the public and other agencies for comment and review.

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Ecological Approach: A type of natural resource planning, management, or treatment that ensures consideration of the relationship among the biotic organisms (including humans) and their abiotic environment.

Edge Effect: The effect of adjoining vegetative communities on the population structure along the margin. Edge effect often provides for greater numbers of species and higher population densities than are found individually in either adjoining community. Edge may result in negative effects because habitat along an edge is different than in the patch of habitat, thus reducing the effective area of the habitat patch.

Effective Alteration Approach (EFFALT): The effective alteration approach is a means of quantifying the degree of visibly-detectable alteration of the landscape caused by even-aged timber management. The EffALT index is a means to compare the overall visual impact of each alteration.

Endangered Species: Any species listed in the Federal Register as being in danger of extinction throughout all or a significant portion of its range.

Ephemeral Stream: Streams that contain running water only sporadically, such as during and following storm events. Ephemeral streams with a definable channel are considered “seasonally flowing” or intermittent when they show evidence of annual scour or deposition. Ephemeral streams without a definable channel are considered swales.

Ephemeral Stream – Swale: A shallow, trough-like depression in the landscape that may be hydraulically connected to stream channels downslope. Swales are sometimes referred to as those ephemeral channels having an undefinable channel and no evidence of scour or deposition. Upslope precipitation, as rainfall or snowmelt, is generally concentrated in swales and directed towards definable stream channels as subsurface flow.

Erosion – Gully Erosion: Erosion of soil or soft rock material by running water that forms distinct, narrow channels larger and deeper than rills, and that usually carry water only during or immediately after heavy rains or following the melting of snow and ice.

Erosion – Rill Erosion: The removal of soil by the cutting of numerous small, but conspicuous, water channels or tiny rivulets by concentrated surface runoff.

Erosion – Rut Erosion: Similar to gully erosion, but associated with a furrow or track on the ground, especially one made by the passage of vehicles.

Even-aged Management Silvicultural System: The trees in the stand are approximately the same age (usually within 20 years of age). The system is designed to manage stands of mostly the same age to a desired age or size, followed by harvest some or all of the trees and regeneration with tree seedlings.

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Fire Area Simulator (FARSITE): The Fire Area Simulator is a computer model used for spatially and temporally simulating the spread and fire behavior under conditions of changing terrain, fuels, and weather.

Fire Regime: The recurring combination of fire occurrence, behavior, effects, and subsequent plant development that are typical of a certain vegetation type.

Fire Return Interval: The period of time between fires.

Fire Risk: Fire risk in this FEIS is defined as the probability that a fire will ocurr. It does not indicate likelihood of a fire becoming large.

Forest Development Roads: Forest Service created roads used for the management, protection, and use of the National Forest System lands.

Forest Plans: The Land and Resource Management Plans for the Plumas, Lassen, and Tahoe National Forests.

Fragmentation: The process of reducing the size and continuity of patches of habitat. For purposes of this FEIS, fragmentation is used in reference to forested areas.

Fuelbed: The amount, structure, and arrangement of forest fuels.

Fuelbreak: A wide strip of land where hazardous fuel has been removed for in anticipation of fighting fires. Fuelbreaks divide fire-prone areas into smaller parcels for easier fire control and provide access for fire fighting.

Fuel Loading: The weight of fuel present at a given site; usually expressed in “tons per acre.” This value generally refers to the fuel that would be available for consumption by fire.

Fuel Profile: The amount and characteristics of live fuel and coarse woody debris in a given area. The amount is referred to as fuel loading, and the characteristics include the horizontal and vertical arrangement and continuity of fuels that affect the spread and intensity of fire.

Fuel Treatment: The rearrangement or disposal of fuels to reduce fire hazard or to accomplish other resource management objectives.

Fuels or Fuels Complex: The structure and arrangement of forest fuels.

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Goshawk Management Area (GMA): A defined management area containing a minimum of 50 acres of habitat that provides suitable conditions for goshawk nesting activities.

Group Selection: An uneven-aged management system that harvests small areas of trees (generally less than two acres). Implementation results in uneven-aged stands consisting of small even-aged groups. The openings created in the stands must remove enough trees to allow for sufficient sunlight and soil moisture for regeneration tree seedlings to survive and grow.

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Hazard tree: A tree that has been identified as a potential risk for failure that would cause injury to a person or property.

Home Range: The area to which activities of an animal are confined during a defined period of time.
Horizontal Structure: This refers to the diversity of vegetation across an area or landscape. Areas that are represented by stands or smaller areas of different age classes or size classes are thought to have good horizontal diversity.

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Individual Tree Selection: Also referred to as single tree selection. This is an uneven-aged management system where the objective is to maintain all age groups across the stand. Harvests are made frequently and the appearance of the stand remains relatively unchanged. Trees are harvested such that the desired number of trees in each age group is maintained.

Interim Rule: Temporary direction to Forest Service managers published in the Federal Register. For purposes of this FEIS two interim rules are of specific importance: (1) the interim rule establishing a moratorium on road building in unroaded areas, and (2) the interim rule for protection of California spotted owl.

Intermittent Stream: Any non-permanent flowing drainage feature having a definable channel and evidence of annual scour and deposition, including ephemeral streams with a definable channel and evidence of annual scour or deposition.

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Key Watershed: A watershed containing habitat for potentially threatened species or stocks of anadromous salmonids or other potentially threatened fish, or a watershed that is greater than six (6) square miles with high quality water and fisheries, that because of its importance must be considered in a management program.


Large-Scale Fire: A very large fire as compared to the natural range of fire sizes in the fire regime of the geographical area considered. Fires that generally exceed the typical fire size are often of high intensity and may cause profound fire effects.

Large Woody Debris: Dead woody material including as boles (stems), limbs, and large root masses. Type and size of material designated as large or coarse woody debris varies among classification systems.

Late Successional Old Growth (Ranks 4 and 5): Delineation of highly ranked late successional old growth (ranks 4 and 5) was a mapping exercise completed for the Sierra Nevada Ecosystem Project (SNEP). Late successional old growth (ranks 4 and 5) are those areas which are of highest old forest value. They generally range from 500 to 5,000 acres in size. Reference the Sierra Nevada Ecosystem Project Report to Congress, Volume II, Appendix 21.1 for more details.

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Management Indicator Species: A plant or animal whose presence in a certain situation or location is a fairly certain sign or symptom that particular environmental conditions are also present.

Meadow Protection Zone: A zone surrounding a meadow or other wetland prescribed for protection and special management designed for meeting the special requirements of meadow ecosystems.

Mechanical Treatment: Refers to the use of machinery to remove timber or treat vegetation in an area. Timber harvest is an example of mechanical treatment.

Monitoring: The collection of information over time, generally on a sample basis to measure change in an indicator or variable, for purposes of determining the effects of resource management treatments in the long-term.

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National Environmental Policy Act (NEPA): An Act passed in 1969 to declare a national policy encouraging productive and enjoyable harmony between humankind and the environment. This Act promotes efforts that prevent or eliminate damage to the environment and biosphere and stimulate the health and welfare of humanity, while enriching the understanding of ecological systems and natural resources important to the nation. The Act established the Council on Environmental Quality.

National Forest Management Act (NFMA): The National Forest Management Act of 1976 amended the Resources Planning Act to direct the Secretary of Agriculture to develop direction and guidance for management of lands and resources of National Forest System lands.

Natural Ambient Air Quality Standards: Standards set by the Environmental Protection Agency that limit the concentration of certain air pollutants that endanger public health or welfare.

NFSPUFF Computer Model: An air quality analysis system used to predict downwind smoke dispersion and particle matter concentrations by simulating a worst-case scenario.

Non-Attainment Area: A geographic area in which the level of a criterion air pollutant is higher than the level allowed under Federal standards set by the Environmental Protection Agency. A single geographic area may have acceptable levels of one criterion air pollutant, but unacceptable levels of other criteria pollutants, resulting in an area that has both attainment and non-attainment status at the same time.

Non-Native Plants: A plant grown outside of its natural range.

Noxious Weeds: An invasive non-native plant specified by law as being especially undesirable, troublesome, and difficult to control.

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Offbase and Deferred Lands: A classification of lands defined by the Act. These lands are treated with resource management activities during the period of the pilot period (not to exceed 5 years).

Old Forest: Old forests are forested areas that look (have physical structure) and act (have ecological processes) as they might have been in the absence of contemporary human activity (before the year 1850). Old forests are characterized as having:

(a) A significant number of trees that approach the biological maximum age for the species present;
(b) A complex horizontal and vertical structure, including both live and dead vegetation, that has been shaped or maintained largely by natural disturbances or their functional equivalents;
(c) An array of plant and animal species that are endemic to the particular region and location: and
(d) Continuity in the above characteristics over large geographic areas (hundreds or thousands of acres).
Overstory: Trees that provide the uppermost layer of foliage in a forest with more than one roughly horizontal layer of foliage.

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PACFISH: An interagency ecosystem management approach for maintaining and restoring healthy, functioning watersheds, riparian areas, and aquatic habitats within the range of Pacific anadromous fish on Federal lands managed by the USDI Bureau of Land Management and the USDA Forest Service.

Patch: A small area (1 to 5 acres) having uniform vegetation characteristics that can be ranked according to its ability to contribute to old forest.

Perennial Stream: A stream or portion of a stream that flows throughout the year. The groundwater table lies above the bed of the stream at all times.

Pilot Project Area: The pilot project is limited to certain Federal lands (National Forest System Lands of the Plumas, Lassen, and Tahoe National Forests) identified on the Map by VESTRA™ Resources, Incorporated (1993) as “Available for Group Selection.”

Planning Area: All National Forest System lands of the Sierraville Ranger District of the Tahoe National Forest, the Plumas National Forest, and the portion of the Lassen National Forest south of State Highway 299. The planning area encompasses lands in other ownerships, as well as Federal lands identified in the Act as “offbase” and “deferred.”

Plant Indicator Species: A plant species that, by its presence, frequency, or vigor, indicates a particular property of the site, particularly of the soil or aquatic areas.

PM2.5: Particulate matter smaller than 2.5 micrometers in diameter. Because of its small size, PM2.5 particles readily lodge in the lungs, thus increasing respiratory and cardiac diseases in humans and other organisms.

PM10: Particulate matter smaller than 10 micrometers in diameter. Because of its small size, PM10 readily lodges in the lungs, thus increasing respiratory and cardiac diseases in humans and other organisms.

Polygons: Polygons are large areas (larger than 500 acres) that are ranked according to old forest criteria. This refers to a mapping exercise done by the Sierra Nevada Ecosystem Project. For example, the average size of polygons on the Lassen, Plumas, and Tahoe National Forests range from 6,600 to 7,400 acres. Polygons are ranked for old forest attributes by the predominance of patch rankings within them.

Prescribed Burning: Management-ignited fire in which areas are burned under controlled conditions.

Protected Activity Center (PAC): This refers to areas of delineation around habitat for a specific animal. Protected activity centers are designed to minimize land disturbance within the delineated area.

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Riparian Area: The strip of land that includes and borders a stream, lake, or other water body including the aquatic and riparian ecosystems and the adjacent upland areas that directly affect it.
Riparian Buffer Area: As described in the Sierra Nevada Ecosystem Project Report to Congress, Volume III, Chapter 5, Appendix 3 - an area adjacent to and upslope of perennial, intermittent, and ephemeral stream channels where the conservation of aquatic resources is the primary management emphasis. Special standards and guidelines govern land use in this area. The area encompasses the aquatic and riparian areas, or community/energy area.

• Community Area: The community area includes the channel and adjacent area of aquatic habitat.
• Energy Area: The energy area is located on adjacent slopes and upstream of the community area. It supplies large woody debris, nutrients, sediment, and other organic debris to the community area.
Riparian Corridor: The riparian area along a stream, lake, wetland, or other water body.

Riparian Habitat Conservation Area (RHCA): Portions of a watershed that contribute to creation and maintenance of fish habitat. Riparian habitat conservation areas may include active channels, inner gorges, floodplains, riparian vegetation, perennial and intermittent streams, wetlands, ponds, lakes, reservoirs, and landslide areas.

Riparian Protection Zone: The streamside management zone, riparian habitat conservation area, or riparian buffer area.

Riparian Restoration: Stream, streamside, and meadow stabilization, rehabilitation, or restoration work.

Riparian Management: Stream, streamside, and meadow management designed specifically to protect or enhance riparian areas.

Road: Motorized vehicular routes managed for licensed vehicles.

Road Closure: A road closed to vehicular traffic that may be reopened in the future. Closure tasks include installation of appropriate closure devices, signing, posting of legal notices, subsequent periodic inspection, and ongoing maintenance of the closure device and drainage system.

Road Management Strategies: The Forest Service employs five road management strategies –
encourage, accept, discourage, eliminate and prohibit.

• The encourage strategy is used to direct forest visitors to important destinations via desirable routes.
• The accept strategy is used when use of a road is allowed, but not encouraged.
• The discourage strategy is used to inform potential users of road conditions that may detract from the experience they may be seeking when visiting the National Forest System lands.
• The eliminate and prohibit strategies are used to close roads as needed, either by physical barriers or regulatory signs and orders.

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Sawlog Removal: The removal of a log that meets minimum regional standards of diameter, length, and defect, intended for sawing into end products.

Sedimentation: The process of sediment deposition, usually resulting from erosion.

Scientific Analysis Team (SAT) Guidelines: The “interim boundaries” of riparian habitat conservation areas delineated along different water bodies and areas of watersheds, in which specific riparian management objectives and standards and guidelines are applied as defined in the document, Viability Assessments and Management Considerations for Species Associated with Late-Successional and Old-Growth Forests of the Pacific Northwest, The Report of the Scientific Analysis Team, a Forest Service publication, March 1993.

Sierra Nevada Ecosystem Project (SNEP): Detailed scientific assessments, case studies, commissioned reports, and background information compiled at the request of Congress covering the Sierra Nevada ecosystem, Volumes I, II, III, and an Addendum, 1996 and 1997.

Soil Hydrophobicity: A condition that occurs when organic matter in litter and upper mineral soil layers is volatized during a fire. Some of the volatilized material moves downward into the soil and condenses to form a water-repellent layer that impedes infiltration. This condition is also known as “water-repellent soil” and may occur naturally in some soils.

Soil Quality Standards (SQS): Threshold values that indicate when changes in soil properties and soil conditions would result in significant change or impairment of productivity potential, hydrologic function, or buffering capacity of the soil. Detrimental soil disturbance is the resulting condition when threshold values are exceeded.

Streamside Management Zones: An administratively designated zone designed to call attention to the need for special management practices aimed at the maintenance or improvement of watershed resources. Streamside management zones may include floodplains and wetlands, riparian areas, inner gorges, perennial streams, intermittent streams, and ephemeral streams showing signs of recurrent annual scour or deposition.

Spotted Owl Habitat Area (SOHA): Areas delineated in Land and Resource Management Plans for purpose of providing nesting and foraging habitat for spotted owls.

Stand: Stands are mapable areas of timber. The criteria used for recognition of a stand depends on the land management objectives. Boundaries may be defined by vegetation, soils, geography, forest uses, or ownership. Size may range from a few acres to hundreds of acres.

Stand Structure Diversity: The horizontal and vertical distribution of components of a forest stand including the height, diameter, crown layers, and stems of trees, shrubs, herbaceous understory, snags, and down woody debris.

Stocking: An indication of growing-space occupancy relative to a pre-established standard.

Strata: A vegetation labeling system used by the Forest Service which uses forest regional types, crown cover densities, and tree size. For ease of forest inventory analysis, strata contains groupings of different CALVEG vegetation types.

Surface Fuels: Fuels located on the ground.

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Thinning From Below: An even-aged silvicultural system. Thinning from below involves the removal of some of the smaller trees in the stand so the remaining large trees have more growing space and are better able to maintain vigor.

Threshold of Concern (TOC): The level of watershed disturbance which, if exceeded, could create adverse watershed or water quality effects, in spite of application of Best Management Practices and other routine mitigation measures. Activities near the threshold of concern create increased risks for adverse water quality effects and a possible need for additional analysis or extraordinary mitigation, including rescheduling of projects.

Threatened and Endangered Species (TES): A plant or animal species identified, defined, and recorded in the Federal Register, as being in danger of extinction throughout all or a significant portion of its range, in accordance with the Endangered Species Act of 1976.

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Unclassified Roads: Routes and wheel tracks that are not part of the authorized or inventoried Forest Development Road System, and not under the jurisdiction of entities.

Underburning: Prescribed burning of the forest floor or understory vegetation for botanical or wildlife habitat objectives, hazard reduction, or silviculture objectives.

Understory: The trees and other woody species growing under the canopies of larger adjacent trees and other woody material.

Uneven-Aged Management Silvicultural System: A silvicultural system where stands are continuously managed to have tree cover on at all times so as to meet desired size and age distributions. Group selection and single-tree selection (also called individual tree selection) are examples of uneven-aged management systems.

Unneeded Roads: Candidate roads for decommissioning that receive minimal or unauthorized use.

Upland Vegetation: A plant species that is nearly always found in upland areas. Upland areas are any areas that do not qualify as a wetland because the associated hydrologic regime is not sufficiently wet to elicit development of vegetation, soils, or hydrologic characteristics associated with wetlands (U.S. Army Corps of Engineers, 1989).

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Vegetation Management: Any activity involving live vegetation, including harvest.

Vertical Structure: Vertical structure refers to the appearance of vegetation from the forest floor to the tallest plants or trees defined by a limited area. Stands or areas which have many different heights, and thereby having much of their surface area occupied by several to many layers of vegetation, are thought to have good vertical density or structure.


Watershed: A region or land area drained by a single stream, river, or drainage network.

Wildfire Susceptibility: Wildfire susceptibility is the combination of the probability of a fire igniting (risk) with the intensity at which it will burn (hazard).