University of Idaho - I Banner
A student works at a computer


U of I's web-based retention and advising tool provides an efficient way to guide and support students on their road to graduation. Login to VandalStar.


UI Extension Forestry

Mailing Address:
875 Perimeter Drive MS 1140
Moscow, ID 83844-1140

Phone: 208-885-6356


Google Maps

University of Idaho Extension, Kootenai County

Mailing Address:
1808 N 3rd St
Coeur d’Alene, ID 83814-3407

Phone: 208-446-1680

Fax: 208-446-1690


Web: UI Extension, Kootenai County

Chris Schnepf Google Maps

UI Extension, Clearwater County

Mailing Address:

2200 Michigan Avenue
Orofino, ID 83544

Phone: 208-476-4434



Acceptable tree species

Any of the tree species normally marketable in the region and suitable to meet stocking requirements. Acceptable trees must be of sufficient health and vigor to assure growth and harvest.

Active road

A forest road being used for hauling forest products, rock or other road building materials.

Aggrading stream

A stream reach where deposition is greater than erosion.

Algal bloom

A sudden increase in the abundance of suspended (planktonic) algae, especially at or near the water surface, producing a green or brown appearance to the water. Excess nutrients can cause an algal bloom.

Anchor cat

A bulldozer or other mobile machine of sufficient weight that, when parked below a hill or on a road, serves as the tailhold for the lower end of a skyline.

Aquatic macroinvertebrate

Animal living in or near water that is large enough to be seen and does not have a backbone.


A fine-grained sedimentary rock composed primarily of clay particles heated under pressure.


The placement of rocks around a culvert inlet or outlet to keep road materials around the pipe secure; also used to minimize soil erosion on unstable cut or fill slopes.

Artificial regeneration

Reestablishment of forest cover following harvest by direct seeding or planting.


A position facing a particular direction; can be expressed as a direction (e.g., north, south, east, west), a compass direction in degrees or a cardinal direction.

Average DBH

Average diameter in inches of a tree, measured at 4.5 feet above mean ground level on standing trees. All trees that do not have a measurable DBH will fall in the 1-inch class.

Balanced cut and fill

A construction method that uses materials excavated on the uphill side of a road as fill material on the downslope side.

Bankfull width

The maximum width a stream channel attains, typically marked by a change in vegetation, topography or texture of sediment.


A common extrusive igneous rock formed from the rapid cooling of basaltic lava exposed at or very near the earth’s surface.

Best management practice (BMP)

A practice or combination of practices determined by the board, in consultation with the Idaho Department of Lands and the Forest Practices Advisory Committee, to be the most effective and practicable means of preventing or reducing the amount of nonpoint source pollution generated by forest practices. BMPs include, but are not limited to, those management practices included in the IFPA Rules.

Biological control

The use of living natural enemies (insects, diseases, nematodes or mites) to reduce plant pest populations.

Borrow pit

An area where native rock material is excavated for use in road fills.

Buffer strip

  1. A protective area adjacent to an area requiring special attention or protection.

  2. A vegetated area adjacent to a water body (e.g., river, stream, wetland or lake); often protected and adjacent to an area requiring special attention or protection.

Certificate of Slash Compliance/Fire Hazard Agreement (Compliance)

An assurance given to the state (Idaho Department of Lands) that fire hazard reduction or management will be performed after a forest operation.


A substance applied to forestlands or timber to accomplish specific purposes; includes pesticides, as defined in the Idaho Pesticide Law, Title 22, Chapter 34, Idaho Code, fertilizers, soil amendments, road dust abatement products and other materials that may present hazards to the environment.

Chemical control

The use of herbicides to control unwanted vegetation.

Class I stream

A stream that is used for domestic water supply or is important for the spawning, rearing or migration of fish. Such waters shall be considered to be Class I upstream for a minimum of 1,320 feet from the point of domestic diversion.

Class I Stream Protection Zone

The area encompassed by a minimum slope distance of 75 feet on each side of the ordinary high water marks.

Class II stream

Usually a headwater stream or minor drainage that is used by only a few, if any, fish for spawning or rearing. Where fish use is unknown, consider streams as Class II when the total upstream watershed is less than 240 acres in the north forest region or less than 460 acres in the south forest region. Their principal value lies in their influence on water quality or quantity downstream in Class I streams.

Class II Stream Protection Zone

The area encompassed by a minimum slope distance of 30 feet on each side of the ordinary high water marks of a Class II stream. For Class II streams that do not contribute surface flow into Class I streams, provide soil stabilization and water filtering by leaving a sufficient width of undisturbed soil to prevent sediments from washing into streams. In no case shall this width be less than 5 feet slope distance on each side of the ordinary high water marks.


A natural, fine-grained material formed from erosion of rock fragments; particles are less than 2 micrometers in size; develops plasticity when mixed with a limited amount of water.

Clearcut system

A silvicultural treatment in which all trees in a unit are harvested in one operation and the area is reforested by planting trees or through natural regeneration.

Climax tree species

The tree species that will dominate if a site is left undisturbed; typically the most shade-tolerant trees capable of growing on a site.

Commercial products

Any saleable forest products of sufficient value to cover the cost of harvest and transportation to market.

Commercial slash

  1. A commercial product derived from fuels and debris following a forest practice such as clearcutting or thinning.

  2. Fuels and debris resulting from a forest practice involving removal of a commercial product; the slash itself does not need to be a commercial product.

Commercial thinning

Thinning when trees are large enough to be sold for a product; revenue generated is potentially sufficient to offset treatment costs.

Condition of adjoining area

Fuel condition in an adjoining area that relates to spread of fire and to economic values of the adjoining area.

Constructed skid trail

A skid trail created by the deliberate cut and fill action of a dozer or skidder blade resulting in a road-type configuration.


To introduce into the atmosphere, soil or water a substance of sufficient quantities so as to be injurious to public health, safety or welfare; to domestic, commercial, industrial, agricultural or recreational uses; or to livestock, wildlife, fish or other aquatic life.


The person on an IDL Notification of Forest Practice and Certificate of Slash Compliance/Fire Hazard Agreement form that is taking responsibility for the slash and who signs on the certificate holder or “Contractor” line.

Control points

The locations or points, a forest road must reach or pass through.

Cross ditch

A diversion ditch and/or hump in a trail or road intended to carry surface water runoff into vegetation, duff, a ditch or other dispersal area so that it does not cause soil movement and erosion.


Nonmerchantable, live, standing trees greater than 20 feet tall.

Cultural control

The deliberate manipulation of plants and their surroundings to favor optimal plant growth; includes choosing the right plant for the site, planting resistant varieties when available, using proper planting techniques, watering, fertilization, pruning and sanitation practices.

Curve widening

The extra width added to a road curve to account for vehicle off-tracking.

Debris flow

A slurry composed of soil, water, vegetation and other debris, with solids composing more than 60% of the volume on average.

Debris slide

An aggregation of coarse soil, rock and vegetation that lacks significant water and moves downslope by sliding or rolling forward at speeds ranging from very slow to rapid.

Deep-seated landslide

A landslide in which the slide plane or zone of movement is well below the maximum rooting depth of forest trees (generally deeper than 10 feet), sometimes extending hundreds of feet in depth and often including bedrock.

Definite bed

A streambed with a sandy or rocky bottom that results from the scouring action of water flow.


The degree of cable “sag” at a cable system’s midpoint distance.

Degrading stream

A stream reach where erosion is greater than deposition.


Accumulation of detached soil particles following overland flow, gravitational/wind erosion or animal activities. Deposition occurs at the bottoms of slopes; in areas of vegetation and surface litter; behind rocks or large organic debris; and in streams, rivers and their floodplains.


The ease with which individual soil particles are detached (soil erodibility); influenced by slope gradient and length.

Deterioration rate

The rate of natural decomposition and compaction of woody debris that decreases fire hazard; varies by site.

Diameter at breast height (DBH)

The diameter in inches of a tree, measured at 4.5 feet aboveground on the uphill side of the tree.

Diameter limit cutting

Harvest of the largest diameter trees in a forest stand.

Dissolved oxygen

The amount of oxygen dissolved in water. Higher amounts of oxygen can be dissolved in colder waters than in warmer waters. Dissolved oxygen is necessary to support fish and other aquatic organisms.

Emergency forest practice

A forest practice initiated during or immediately after a fire, flood, windthrow, earthquake or other catastrophic event to minimize damage to forestlands, timber or public resources.

End haul

Transport of excess excavated materials from a newly constructed road to a disposal area.

Ephemeral stream

A stream that flows during the wet season and is dry during the dry season; lacks defined bed or banks.


  1. The movement of individual soil particles by wind or water, usually described by three components: detachment, transport and deposition.

  2. The wearing down and removal of soil, rock fragments and bedrock through the action of flowing water, wind, moving ice and gravitational creep (mass movement).


The process by which water not absorbed by vegetative canopies or soil changes to water vapor and is lost to the atmosphere.


The loss of water to the atmosphere from the combined effects of interception, transpiration and direct evaporation from vegetation, ground surfaces and water bodies.

Even-aged silvicultural system

A silvicultural system that regenerates and maintains even-aged stands; includes clearcut, seed tree and shelterwood systems.


Any substance or combination of substances used principally as a source of plant nutrients or soil amendment.

Fire trail

An access route located and constructed in a manner to be useful in fire control efforts or to deter fire spread in a hazard area.


The flow of a large volume of water beyond its normal confines, especially over what is normally dry land.


The area on both sides of a stream where flood waters spread out. The surface may appear dry for most of the year, but is generally occupied by plants adapted to wet soils.

Forest practice

  1. The harvesting of forest tree species, including felling, bucking, yarding, decking, loading and hauling; road construction, improvement or maintenance, including installation or improvement of bridges, culverts or structures that convey streamflows within the operating area; the clearing of forestland for conversion to nonforest use when harvest occurs.

  2. Road construction, reconstruction or maintenance of existing roads, including installation or improvement of bridges, culverts or structures that convey streams not within the operating area associated with harvesting of forest tree species.

  3. Reforestation.

  4. Use of chemicals for the purpose of managing forest tree species or forestland.

  5. Management of slash resulting from harvest, management or improvement of forest tree species or the use of prescribed fire on forestland.

  6. “Forest Practice” shall not include preparatory work such as tree marking, surveying, road flagging or removal or harvesting of incidental vegetation from forestlands, such as berries, ferns, greenery, mistletoe, herbs, mushrooms or other products that cannot normally be expected to result in damage to forest soils, timber or public resources.

Forest regions

Two designated regions of Idaho forestland: one is north of the Salmon River and the other is south of the Salmon River.

Forest type

  1. A category of forest usually defined by its vegetation, particularly its dominant vegetation as based on percentage cover of trees.

  2. The Idaho Forest Practices Act delineates five forest types in Idaho:

    • North Idaho grand fir/western redcedar (NIGF): moist to wet interior forests with western redcedar, western hemlock and grand fir being primary climax species; found in forests north of the Clearwater and Lochsa rivers.
    • Central Idaho grand fir/western redcedar (CIGF): productive conifer forests found between the Lochsa River Basin and the Salmon River, characterized by stands having western redcedar and grand fir as climax species, with a mixed conifer overstory increasingly comprised of ponderosa pine, Douglas-fir and larch in the river breaks canyonlands. Stocking levels are generally lower than in NIGF stands.
    • South Idaho grand fir (SIGF): mixed conifer forests, dominated by ponderosa pine and Douglas-fir, found south of the Salmon River, with grand fir and occasionally western redcedar being the stand climax species.
    • Western hemlock/subalpine fir (WH): higher elevation, moist, cool interior forests dominated by western hemlock, mountain hemlock and/or subalpine fir.
    • Douglas-fir/ponderosa pine (PP): drier forests dominated by ponderosa pine and Douglas-fir, generally found in lower elevation, dry sites.


Federal, state and private land growing forest tree species that are or could be at maturity, capable of furnishing raw material used in the manufacture of lumber or other forest products. The term includes federal, state and private land from which forest tree species have been removed but have not yet been restocked. It does not include land affirmatively converted to uses other than the growing of forest tree species.

Fuel quantity

  1. The quantity of fuel per unit area, as determined by tree diameter, number of stems, predominant species to be cut or already cut and the size of the continuous thinning block.

  2. The amount of woody debris, measured in tons per acre, existing on a site or to be produced by a forest management activity.

Full-bench construction

The excavation of a hill slope so that the entire road surface is cut into the hillside, without using fill materials on the downhill side.


Synthetic fabric used to separate layers of soil and rock during road construction; particularly useful on soils that do not compact properly for effective hauling.

Ground-based equipment

Mobile equipment such as tractors, dozers, skidders and mechanized harvesters used for harvesting, site preparation or hazard reduction; does not include cable systems associated with stationary yarding equipment.


Water found beneath the earth’s surface.

Group selection system

A harvest selection system in which small groups of trees, typically no more than 3 acres, are removed.

Habitat type

  1. A forestland unit capable of producing similar plant communities at climax.

  2. An aggregation of land units capable of producing similar plant communities at climax.


A commercial activity related to the cutting or removal of forest trees to be used as forest products; does not include the cutting or removal of forest tree species by a person for his or her personal use.


Any vegetative residue resulting from a forest practice that constitutes fuel.

Hazard offset

Improvements or a combination of practices that reduce the spread of fire and increase the ability to control fires.

Hazard points

The number of points assigned to hazardous conditions on an operating area; to actions designed to modify conditions on the same area; or to actions by the operator, timber owner or landowner to offset hazardous conditions on the same area.

Hazard reduction

The burning or physical reduction of slash by treatment in some manner that will reduce the risk from fire after treatment.

Hydrologic cycle

The continuous movement of water among the oceans, air and earth in the form of precipitation, percolation, evapotranspiration and stream discharge.


A planting process that uses a slurry of seed and mulch to stabilize soil after disturbance.


A plant adapted to living in aquatic environments; also referred to as an aquatic plant.

Hyperconcentrated flood

A flowing mixture of water, sediment (predominantly sand size) and organic debris, with solids ranging between 20 and 60% by volume.


A condition of low dissolved oxygen levels in a water body that can result from the decay of plants and algae.


Idaho Department of Lands.


Idaho Forest Practices Act, Title 38, Chapter 13, Idaho Code.

Inactive road

A forest road (a road whose primary purpose is for forest practices) no longer used for commercial hauling but maintained for access (e.g., for fire control, forest management activities, recreational use and/or occasional or incidental minor forest products harvesting).

Incidental haul road

A multi-use road that has log haul during active harvest activities; however, the primary purpose of the road is other than forest practices (e.g., residential traffic).

Individual tree selection system

An uneven-aged silvicultural system in which individual trees of all sizes and age classes are removed throughout the stand to promote growth of remaining trees and to provide space for regeneration.


The absorption of water by soil.

Infiltration rate

The rate at which water soaks into the soil; determined by the percent of vegetative cover, vegetative cover type, soil volume-weight, moisture content and amount of dead organic material and other protective cover.

Insloped road

A road that slopes toward the uphill side of a road profile; most commonly used to divert water into a ditch on the uphill side of the road.

Integrated Pest Management (IPM)

A strategy that uses a combination of effective and environmentally sensitive controls to manage unwanted vegetation by the most economical and least hazardous means.


The process by which precipitation is caught by vegetation or other surfaces before it reaches the ground.

Intermittent stream

A stream that flows when there is adequate precipitation and is dry at other times; usually has defined bed and banks.


A body of perennial standing open water, natural or human-made, larger than 1 acre in size. Lakes include the beds, banks or wetlands below the ordinary high water mark.


A cleared area in the forest to which logs are yarded or skidded for loading onto trucks for transport to processing sites.


A person, partnership, corporation or association of any type that holds an ownership interest in forestlands, including the state.

Large organic debris (LOD)

  1. Live or dead trees and parts or pieces of trees that are large enough or long enough or sufficiently buried in the stream bank or streambed to be stable during high flows. Pieces longer than the channel width or longer than 20 feet are considered stable.

  2. Logs left outside the SPZ for wildlife and long-term soil health. The type and size of LOD varies among classification systems and is sometimes referred to as coarse woody debris (CWD), large woody debris (LWD) or down woody debris (DWD).

Leaf litter

Plants and plant parts that have recently fallen and are partially or not at all decomposed.


A new layer of graded and compacted road material.

Location line (l-line)

The final location chosen for new road construction.

Long-term inactive road

A road not intended to be used again in the near future, but likely to be used at some future time.

Lowboy trailer

A low-slung trailer designed to transport large machinery.

Low-volume road

A road typically constructed to manage or extract resources from rural or undeveloped areas and designed to accommodate low traffic volumes with potentially extreme axle loads.

Magmatic activity

The rise of liquid magma below the earth’s surface.

Mass haul

Excess material excavated from road cuts used to fill in low areas.

Mass haul requirement

The extent to which excess material from road cuts in one area must be removed and used to fill in adjacent low areas.

Merchantable material

That portion of forest trees suitable for the manufacture of commercial products that can be merchandised under normal market conditions.

Merchantable stand of timber

A stand of trees that will yield logs or fiber, suitable in size and quality for the production of lumber, plywood, pulp or other forest products, of sufficient value at least to cover all costs of harvest and transportation to markets.


Intermediate moisture conditions (i.e., neither decidedly wet nor dry).

Metamorphic activity

The change in existing minerals or rock structure due to heat and pressure.


Animals that have no backbone and are too small to be seen by the unaided eye.


Relating to mountains.

Natural regeneration

Reestablishment of forest cover by seed from nearby trees following harvest activities.

Noncommercial forestland

Habitat types not capable of producing 20 cubic feet per acre per year of usable wood.

Noncommercial slash

Fuels and debris resulting from a forest practice where no commercial product is removed.

Nonpoint source pollution

Polluted runoff that is not readily identifiable as originating from any one particular point; includes pollution caused by runoff from streets, agricultural land, forest roads, construction sites and parking lots.

Notification of Forest Practice (Notification).

A notice to the state (Idaho Department of Lands) that a forest practice is going to be conducted.

Noxious weeds

Plants that have been designated by a county, state or national agricultural authority as injurious to native habitats, croplands, humans, native fauna and/or livestock; nonnative species that grow aggressively and multiply quickly, due in part to a lack of natural control agents such as insects, diseases or herbivores.


Any element necessary for the growth of living organisms.

Nutrient enrichment

Elevated levels of nitrogen and/or phosphorus in a water body that result in undesirable growth of algae or other aquatic plants.


Action by which the rear axle of a truck follows a different path than the front of the vehicle and travels farther inside on the curve.

Operating area

The area where a forest practice is taking place or will take place.


  1. A person who conducts or is required to conduct a forest practice.

  2. The person on an IDL Notification of Practice and Certificate of Slash Compliance/Fire Hazard Agreement form that is taking responsibility for complying with forest practices and signs on the “Operator” signatory line.

Ordinary high water mark

The mark on a water course found by examining the beds and banks and ascertaining where the presence and action of waters are so common and usual and so long continued in all ordinary years, as to mark upon the soil a character distinct from that of the abutting upland, in respect to vegetation; this determination is made based on conditions existing on the effective date of the IFPA.

Organic matter

Plant and animal material.

Outsloped road

A road that slopes outward, in the same direction as the slope.


The excess material from constructing forest roads, produced by cut and fill operations or full-bench construction.

Overland flow

Water that moves over the ground surface; also called surface runoff.


A building block of soil; an aggregation of soil particles defining a soil’s structure.

Perennial stream

A continuously flowing stream.

Permanently abandoned road

A road not intended to be used again.

Point source pollution

Pollutants originating from a “point” source, such as a pipe or vent.


An undesirable change in the environment, usually resulting from the introduction of abnormally high concentrations of hazardous or detrimental substances, such as nutrients or sediment; the presence of any substance that harms the environment.


Water from the atmosphere that reaches plants, the ground or water bodies; includes rain, snow, sleet, hail and condensation, such as dew or frost.

Precommercial thinning

A thinning practice by which trees that are too small to be sold for wood products are removed from a stand to meet forest management objectives. A net cost is incurred by the landowner.

Preliminary line (p-line)

A “first glance” route that is initially planned by a landowner, forester or contractor for a new low-volume forest road.

Prescribed fire

The controlled application of fire to wildland fuels in either their natural or modified state, under such conditions of weather, fuel moisture and soil moisture so as to allow the fire to be confined to a predetermined area and at the same time to produce the intensity of heat and rate of spread required to meet objectives.

Prescribed livestock grazing

The intentional use of livestock to achieve vegetation management goals.

Present condition of area

The amount or degree of hazard present before a thinning operation commences.

Public resource

Water, fish, wildlife and capital improvements of the State or its political subdivisions.


The ponding of water on the soil surface following disturbance associated with heavy equipment; primarily occurs on fine-textured soils with high soil water content.


A coarse-grained sedimentary rock composed primarily of quartz-rich sandstone heated under pressure.

Reference tag

An identification tag used to identify road centerline and drainage device locations.


The establishment of an adequately stocked stand of trees of species acceptable to IDL to replace those removed by harvest or by a catastrophic event on commercial forestland.

Relative stocking

A measure of site occupancy calculated as a ratio comparison of actual stand density to the biological maximum density for a given forest type. This ratio, expressed as a percentage, shows the extent to which trees utilize a plot of forestland.

Relief culvert

A structure to relieve surface runoff from roadside ditches to prevent excessive buildup in water volume and velocity.

Riparian area

An area adjacent to and along a watercourse that constitutes a buffer zone between nearby lands and the watercourse; the natural plant community adjacent to a stream.


Any material (such as concrete blocks, rocks or log pilings) used to stabilize a watercourse and reduce erosion.

Road standards

A list of specifications for road designs.


Water from rain, snowmelt or irrigation that flows over the ground surface and runs into a water body.


A family of ray-finned fish including salmon, trout, chars, freshwater whitefishes and graylings.


A natural, coarse-grained material formed from erosion of rock fragments; particle sizes range from greater than 0.0625 millimeters but less than 2 millimeters in diameter.


Eroded soil particles (soil, sand and minerals) transported by water.

Sediment trap

A temporary device installed on a construction site to capture eroded or disturbed soil that is washed off during rainstorms; designed to protect the water quality of a nearby stream, river or lake.


  1. The process by which soil particles (sediment) enter a water body, settle to the bottom and accumulate.

  2. The addition of soil to lakes or streams.

Seed tree system

An even-aged silvicultural system similar to a clearcut, except that 5 to 10 trees per acre are left evenly distributed across the site to produce tree seed.

Selection system

An uneven-aged silvicultural system that attempts to maintain a range of desired tree sizes, species and ages by harvesting individual trees or small groups of trees.

Shelterwood system

An even-aged silvicultural system similar to the seed tree system, except that more trees are left to “shelter” the site until new trees are established.


Fine particles of soil and minerals formed from erosion of rock fragments; particle size ranges from 0.004 to 0.0625 millimeters.


A fine-grained sedimentary rock composed primarily of silt-sized minerals heated under pressure.

Silvicultural system

A specific set of practices designed to create favorable growing conditions for desired tree species.


The art and science of controlling the establishment, growth, composition, health and quality of forests and woodlands to meet the diverse needs and values of landowners and society on a sustainable basis.


An area characterized by ecological factors, with reference to capacity to produce forest vegetation; the combination of biotic, climatic and soil conditions of an area.

Site factor

A combination of percent of average ground slope and dominant aspect of the forest practice area as they affect the rate of fire spread.

Site preparation

Hand or mechanized manipulation of a site, designed to enhance the success of tree regeneration.

Size of thinning block

Acres of continuous fuel creating an additional hazard within a forest practice area. Distance between the perimeter of adjacent thinning blocks containing continuous fuel must be a minimum of six chains (396 feet) apart to qualify as more than one block.


  1. Any vegetative residue 3 inches in diameter or smaller resulting from a forest practice or the clearing of land.

  2. All brush, severed limbs, poles, tops and/or other organic waste material generated by harvest, other types of land clearing or storm damage.

Slash mat

Harvest residue dispersed on skid trails or landings to reduce erosion and soil compaction.


  1. A dead, standing tree 20 feet or greater in height.

  2. A standing, generally unmerchantable dead tree from which the leaves and most of the branches have fallen.


The mixture of minerals, organic matter, gases, liquids and micro- and macroorganisms that supports plant life.

Soil stabilization

Efforts taken to minimize soil erosion.

Soil strength

A soil’s overall cohesion, determined by structural units called peds; larger peds increase soil strength.

Soil survey

The process of classifying soil types and other soil properties in a given area and geo-encoding such information; usually performed by the USDA Natural Resources Conservation Service.

Soil texture

A qualitative analysis of soil based on the percentage of sand, silt and clay.


Stream Protection Zone. See Class I and Class II definitions.


A contiguous group of trees sufficiently uniform in age-class distribution, composition and structure and growing on a site of sufficiently uniform quality, so as to be a distinguishable unit.

Strahler Stream Classification System

A stream order classification system that assigns each headwater stream an order of 1; at the confluence of two first-order streams, the downstream reach is assigned an order of 2. The confluence of two second-order streams results in a downstream reach of order 3 and the confluence of two third-order streams results in a downstream reach of order 4.


A natural watercourse of perceptible extent with a definite bed and banks that confine and conduct continuously or intermittently flowing water.

Stream bank

The sides of a stream that contain water flow, except during floods.

Stream discharge

The amount of water moving in a stream in a given amount of time, also known as flow.


The bottom of a stream where the substrate and sediments lie.


The process by which snow changes from solid to gas (water vapor), bypassing the liquid phase.


  1. The surface upon which an organism lives or is attached.

  2. The material making up the bottom of a streambed.

Substrate embeddedness

The degree to which large particles (boulders or gravel) in a stream are surrounded or covered by fine sediment.

Subsurface water

  1. Any water that flows through the soil and underground rock crevices.

  2. Groundwater


The shift in forest species composition over time.


The downhill anchor point of the primary cable in a skyline system.

Tectonic plate

A section of the earth’s crust and uppermost mantle.

Thermal pollution

Water temperatures that are too warm to maintain oxygen at levels necessary to support desired aquatic species necessary to support desired aquatic species.


Removing trees from a stand to reduce stand density, select for healthier and higher quality crop trees and improve growth and log quality of remaining trees.

Through cut

A road cut used to avoid an overly steep road grade, such as on the crest of a steep hill or a cut through a hill slope used to minimize road curves.

Through fill

A raised road bed on flat terrain where water is likely to pond; used to cross draws or wet or swampy ground; also called a turnpike.

Timber owner

A person, partnership, corporation or association of any type, other than the landowner, that holds an ownership interest in forest tree species on forestland.

Time of year of forest practice (relating to hazard reduction)

Those combinations of months during which the forest practice is taking place. Points assigned are: October through December–2 points; August through September–4 points; January through April–7 points; May through July–10 points.


The measure of water clarity; affected by the amount of material (sediment, algae and plankton) suspended in water.


The uptake of soil water by plants and its evaporation to the atmosphere through leaves and other plant surfaces.


Movement of detached soil particles from one place to another by overland flow, gravity, wind or animal activity.

Trial grade

A rough estimate of the slope along a planned road route.


The presence of sediment in water, making it unclear, murky or opaque.

Uneven-aged silvicultural system

A harvest system designed to maintain a variety of tree ages and diameters within a stand by frequently harvesting small volumes.


One or several forest stands used to indicate a geographical or management area.


Volcanic eruptions and lava flows.

Water quality

The condition of water with regard to the presence or absence of pollution.


  1. The area of land that drains water, sediment and dissolved materials to a common outlet at some point along a stream channel.

  2. A region or area of land that drains into a body of water such as a lake, river or stream.


A shallow body of water that may or may not have water in it year-round.


A plant community in which, in contrast to a typical forest, the trees are characteristically small and short boled relative to their crown depth; the canopy is more open, with the intervening area being occupied by lower vegetation, commonly grass.


A relatively new technology that combines a yarder and a loader and results in a smaller version of a yarder that is easier to move and set up.


UI Extension Forestry

Mailing Address:
875 Perimeter Drive MS 1140
Moscow, ID 83844-1140

Phone: 208-885-6356


Google Maps

University of Idaho Extension, Kootenai County

Mailing Address:
1808 N 3rd St
Coeur d’Alene, ID 83814-3407

Phone: 208-446-1680

Fax: 208-446-1690


Web: UI Extension, Kootenai County

Chris Schnepf Google Maps

UI Extension, Clearwater County

Mailing Address:

2200 Michigan Avenue
Orofino, ID 83544

Phone: 208-476-4434