Anaerobic - Occurring in the absence of free oxygen.

Angle of repose - The maximum slope or angle at which a material, such as soil or loose rock, remains stable (stable angle).

Bank - The land surface abutting the bed of any navigable waterway which, either prior to any project or alteration of land contours or as the result of the proposed project or alteration, slopes or drains without complete interruption into the waterway.

Basal area - The cross-sectional area of a single stem, including the bark, measured at breast height (4.5 ft or 1.37 m above the ground).  The cross-sectional area 41/2 feet above ground expressed in square feet per acre of all trees with a diameter of 5 inches and larger.

Baseflow - The portion of streamflow which comes from groundwater.

Best Management Practices (BMPs) - Practical and economically achievable practices for preventing or reducing nonpoint source pollution.

Broad-based dip - A surface drainage structure specifically designed to drain water from an access road while vehicles maintain normal travel speeds.

Brush barrier - A sediment control structure created of slash materials piled at the toe slope of a road or at the outlets of culverts, turnouts, dips and water bars.

Buffer area - A designated area around a stream or waterbody of sufficient width to minimize entrance of forestry chemicals (fertilizers, pesticides, and fire retardants) into the waterbody.

Check dam - A small dam constructed in a gully to decrease the flow velocity, minimize channel scour and promote deposition of sediment.

Clearcutting - A stand in which essentially all trees have been removed in one operation (depending on management objectives, a clearcut may or may not have reserve trees left to attain goals other than regeneration).

Contour - An imaginary line on the surface of the earth connecting points of the same elevation.  A line drawn on a map connecting the points of the same elevation.  The steeper the slope, the closer the contour lines.

Corduroy - A road built of logs laid side by side transversely.

Crown - A convex road surface that allows runoff to drain to either side of the road prism.

Culvert - A metal, wooden, plastic, or concrete conduit through which surface water can flow under or across roads.

Cumulative effect -  The impact on the environment that results from the incremental impact of an action when added to other past, present and reasonably foreseeable future actions regardless of what agency or person undertakes such action.

Cut-and-fill - Earth-moving process that entails excavating part of an area and using the excavated material for adjacent embankments or fill areas.

DBH - Diameter at breast height; the average diameter (outside the bark) of a tree 4.5 feet above mean ground level.

Disking (harrowing) - A mechanical method of scarifying the soil to reduce competing vegetation and to prepare a site to be seeded or planted.

Drainage structure - Any device or land form constructed to intercept and/or aid surface water drainage.

Duff - The accumulation of needles, leaves, and decaying matter on the forest floor.

Erodible soils - Soils that are likely to have high soil loss when exposed to water runoff.  Soils having a Natural Resources Conservation Service (NRCS) erosion hazard rating of "moderate" or "severe" should be considered erodible.  Erosion hazard ratings for different soil types are listed in "Woodland Suitability" tables in NRCS soil survey manuals.  Generally, forest soils occurring on 15 to 35% slopes have a moderate rating and soils occurring on greater than 35% slopes have a severe rating.  Contact your local NRCS office for more information.

Erosion - The process by which the surface of the earth is worn away by the action of wind or water in the form of rain drops, surface runoff, and waves.

Felling - The process of cutting down standing trees.

Fill slope - The surface formed where earth is deposited to build a road or trail.

Firebreak - Naturally occurring or human-made barrier to the spread of fire.

Fireline - A barrier used to stop the spread of fire constructed by removing fuel or rendering fuel inflammable by use of fire retardants.

Fire retardant - Any substance except plain water that by chemical or physical action reduces flammability of fuels or slows their combustion rate.

Floodplain - Land which has been or may be covered by flood water during the regional flood (floods expected to occur once in every 100 years).

Ford - Submerged stream crossing where the streambed may need to be reinforced to bear intended traffic.

Forest filter strip - Area between a stream and construction activities that achieves sediment control by using the natural filtering capabilities of the forest floor and litter.

Forest road - A temporary or permanent road connecting the most remote parts of the forest land to existing public roads.  They provide access to forest lands for timber management, fish and wildlife habitat improvement, fire control, and a variety of recreational activities.

Forwarding - The operation of moving timber products from the stump to a landing for further transport.

Geotextile - A product used as a soil reinforcement agent and as a filter medium.  It is made of synthetic fibers manufactured in a woven or loose nonwoven manner to form a blanket-like product.

Grade (gradient) - The slope of a road or trail expressed as a percentage of change in elevation per unit of distance traveled.

Harvesting - The felling, skidding, processing, loading, and transporting of forest products.

Hydric soil - A soil that is wet long enough to periodically produce anaerobic conditions, thereby influencing the growth of plants.

Hydrophyte - A plant that has evolved with adaptations to live in aquatic or very wet habitats, e.g., a cattail, water lily, or water tupelo.

Intermittent stream - A stream that flows only after rainfall or snowmelt and, therefore, is dry most of the year.

Invertebrate - animals lacking a spinal column.

Lake - A still waterbody which (1) is navigable, (2) has an ordinary high-water mark and (3) has a bed that indicates "reasonably permanent" surface water.

Landing (log deck) - A place in or near the forest where logs are gathered for further processing or transport.

Large woody debris - Large logs, generally at least 12 inches in diameter with an anchored root ball, that have fallen into streams creating stable structures and a diversity of cover conditions and habitat for aquatic organisms.

Logging debris - See slash.

Mulch - A natural or artificial layer of plant residue or other materials covering the land surface that conserves moisture, holds soil in place, aids in establishing plant cover, and minimizes temperature fluctuations.

Mulching - Providing any loose covering for exposed forest soils, such as grass, straw, bark, or wood fibers, to help control erosion and protect exposed soil.

Navigable - Capable of being used by humans for water-borne transportation.

Nonpoint source pollution - Occurs when rainfall or snowmelt runoff moves across the ground, carrying pollutants into streams, lakes, wetlands, and groundwater.  For example, soil can become a pollutant when water runoff moves across a road and carries large amounts of soil into a waterbody.

Ordinary high-water mark - The point on the bank or shore up to which the presence and action of the water is so continuous as to leave a distinct mark either by erosion, destruction of terrestrial vegetation, or other easily recognized characteristic.

Organic debris - Particles of vegetation or other biological material that can degrade water quality by decreasing dissolved oxygen and by releasing organic solutes during leaching.

Outslope - To shape the road surface to cause drainage to flow toward the outside shoulder.

Perennial stream - A stream that flows throughout most of the year.

Prescribed burning - Skillful application of fire to natural fuels that allows confinement of the fire to a predetermined area and at the same time produces certain planned benefits.

Raking - A mechanical method of removing stumps, roots, and slash from a future planting site.

Regeneration - The process of replacing older trees removed by harvest or disaster with young trees.

Regional flood - A flood which is expected to occur on a particular lake, river or stream once in every 100 years (also called the 100-year flood).

Riprap - Rock or other large aggregate that is placed to protect streambanks, bridge abutments, outflow of drainage structures, or other erodible sites from runoff or wave action.

Rut - A depression made by the passage of a vehicle or equipment.

Scarification - The process of removing the forest floor or mixing it with the mineral soil by mechanical action preparatory to natural or direct seeding or the planting of tree seedlings.

Sediment - Solid material, both mineral and organic, that is in suspension and being transported from its site of origin by the forces of air, water, gravity, or ice.

Seepage - Water escaping through or emerging from the ground along an extensive line or surface, as contrasted with a spring where the water emerges from a localized spot.

Shearing - A site preparation method that involves the cutting of brush, trees, or other vegetation at ground level using tractors equipped with angles or V-shaped cutting blades.

Silt fence - A temporary barrier used to intercept sediment-laden runoff from small areas.

Silviculture - 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.

Site preparation - A silvicultural activity to remove unwanted vegetation and other material, and to cultivate or prepare the soil for regeneration.

Skid - Short-distance moving of logs or felled trees from the stump to a point of loading.

Skid trail - A temporary, nonstructural travel way for logging equipment, called skidders, to drag felled trees or logs to the landing for further processing, loading, and transport.

Slash - Any tree tops, limbs, bark, abandoned forest products, windfalls or other debris left on the land after timber or other forest products have been cut.

Slope - Degree of deviation of a surface from the horizontal, measured as a numerical ratio, as a percent, or in degrees.  Expressed as a ratio, the first number is the horizontal distance (run) and the second number is the vertical distance (rise), as 2:1.  A 2:1 slope is a 50 percent slope.  Expressed in degrees, the slope is the angle from the horizontal plane, with a 90 degree slope being vertical (maximum) and a 45 degree slope being a 1:1 slope.

Stand - A contiguous group of trees sufficiently uniform in species composition, arrangement of age classes, and condition to be a homogeneous and distinguishable unit.

Stream - A watercourse that: (1) has an ordinary high-water mark, (2) has bed and banks, (3) flows at least periodically, (4) has an easily identifiable beginning and end, (5) does not lose its character as a watercourse even though it may break up and disappear temporarily and reappear downstream.

Streamside Management Zone (SMZ) - Land and vegetation areas next to lakes and streams where management practices are modified to protect water quality, fish and other aquatic resources.  These areas are complex ecosystems that provide food, habitat and movement corridors for both aquatic (water) and terrestrial (land) communities as well as helping to minimize nonpoint source pollution impacts to surface water.  Also called Riparian Management Zone (RMZ).

Transpiration - Evaporation which enters the atmosphere from the soil through plants.

Turnout - A drainage ditch that drains water away from roads and road ditches.

Vertebrate - animals with a segmented spinal column.

Water bar - A shallow channel or raised barrier of soil or other material laid diagonally across the surface of a road or skid trail to lead water off the road and prevent soil erosion.  Water bars are used to minimize erosion and provide conditions for natural or artificial revegetation.

Wetland - An area where water is at, near or above the land surface long enough to be capable of supporting aquatic or hydrophytic (water loving) vegetation and which has soils indicative of wet conditions.

Wet line - A line of water, or water and chemical fire retardant, sprayed along the ground, and which serves as a temporary fireline from which to ignite or stop a low-intensity fire.

Windrow - Logging debris and unmerchantable woody vegetation that has been piled in rows to decompose or to be burned; or the act of constructing these piles.

Yarding - Method of transport from harvest area to storage landing.