Forestry Terms - S -
SALE, LUMP SUM (BOUNDARY) - The sale of specified timber on a specified area. The volume may or may not be estimated and published. The buyer is responsible for determining correct volume. The seller guarantees ownership and boundaries.
SALE UNIT - A timber sales arrangement in which the buyer pays for forest products removed in units (measured in cords, MBF, or units of weight). Determination of units removed from the area is verified by mill tally, scale tickets, and buyer's or seller's tally.
SALVAGE CUT - The harvesting of dead or damaged trees or of trees in danger of being killed by insects, disease, flooding, or other factors in order to save their economic value.
SAPLING - A small tree, usually between 2 and 4 inches diameter at breast height.
SAWLOG or SAWTIMBER - A log or tree that is large enough (usually 10 to 12 inches in diameter) to be sawed into lumber. Minimum log length is typically 8 feet.
SAWLOG LENGTH: The length in feet of the merchantable portion of a sawtimber growing-stock tree.
SAWLOG TOP DIAMETER: The span of the tree stem outside bark (d.o.b.) at the top of the SAWLOG LENGTH of the bole.
SCALE -lb measure the weight or volume of a log or load of logs.
SCALING -Determination of the gross and net volume of logs using the customary commercial volumetric units for the product
SCALPING -Removing small plants and duff or ashes from around the spot where a tree
seedling will be planted. Usually done by hand rather than by machine.
SCARIFICATION -Shallow loosening of the soil surface.
SCARIFYING - For soil: The removal of the top litter layer of an area (usually in strips) for site preparation. For seed: The abrasion or weakening of the seed coat to encourage germination.
SCRIBNER RULE -Diagram log rule, one of the oldest in existence, that assumes 1-inch
boards and a 1/4-inch kerf, makes a liberal
allowance for slabs, and disregards taper.
-Official rule of the Canadian Forestry Branch, Department of Resources and Development. Also used in many parts of the
United States (26).
SEALED BID SALE -Sale in which interested parties submit written bids at the time and place specified.
SEASONED -Wood that has been dried to a certain moisture content to improve its serviceability. According to the grading
standards of the Western Wood Products Assoc., seasoned softwood lumber is defined as having a moisture content of 19
percent (ovendry basis) or less.
SECONDARY LOGGING ROAD -Road designed for relatively little use. Typically a dirt road, with no gravel, used only during dry weather.
SECOND GROWTH -Trees that come up naturally after the first growth of timber has been
cut or destroyed by fire. Also known as young timber.
SECTION -Land survey subdivision. Usually one square mile (640 acres).
SEDIMENTATION - The deposition or settling of soil particles suspended in water.
SEEDBED -Area prepared to receive seeds, such as an area cleared of plants and duff, so that natural seed fall can establish a
SEEDLING - (a) A tree, usually less than 2 inches diameter at breast height, that has grown from a seed rather than from a sprout. (b) A nursery-grown tree that has not been transplanted in the nursery.
SEEDLING/SHRUB COUNT: The number of established tree seedlings or shrub stems on a fixed area or sample plot.
SEED TREE CUT - A harvesting method in which a few scattered trees are left in the area to provide seed for a new forest stand. Selection of seed trees should be based upon growth rate, form, seeding ability, wind firmness, and future marketability. This harvesting method produces an even-aged forest.
SEED YEAR - A year in which a given species produces a large seed crop over a sizable area. Some species of trees produce seeds irregularly.
SELECTIVE CUTTING - The periodic removal of individual trees or groups of trees to improve or regenerate a stand.
SELECTION SYSTEM -Uneven-aged silvicultural system in which single or small groups of
trees are periodically selected to be removed from a large area so that age and size
classes of the reproduction are mixed (20).
SELECTION THINNING -Removal of dominants that have exceeded the diameter limit prescribed, in favor of smaller trees with good growth form and condition. This will promote conversion to a selection forest (26).
SHADE-INTOLERANT TREES - Trees that cannot thrive in the shade of larger trees.
SHEARING - Slicing or cutting trees or stumps at the ground line. Shearing may be done at harvest or with a KG blade during site preparation.
SHELTERWOOD CUT - Removing trees on the harvest area in a series of two or more cuttings so new seedlings can grow from the seed of older trees. This method produces an even-aged forest.
SHELTERWOOD LOGGING -Method of harvesting timber so that selected trees remain
scattered throughout the tract to provide seeds for regeneration and shelter for
SHELTERWOOD SYSTEM -Even-aged silvicultural system in which a new stand is established under the protection of a partial canopy of trees. The mature stand is generally removed in a series of two or more cuts, the last of which is when the new
even-aged stand is well developed.
SHRUB: A plant that has persistent woody stems and a relatively low growth habit, and that generally produces several basal shoots instead of a single bole. It differs from a tree by its low stature and nonarborescent form. Usually less than 16 ft. tall at maturity.
SHRUBLAND: Areas on which vegetation is dominated by shrubs, provided these areas do not qualify as Built-up land or Cultivated cropland. Examples are areas consisting of such species as big sagebrush, shadscale, greasewood, creosotebush, and fourwing saltbrush.
SILVICULTURE - The art, science, and practice of establishing, tending, and reproducing forest stands of desired characteristics. It is based on knowledge of species characteristics and environmental requirements.
STEWARDSHIP INCENTIVE PROGRAM (SIP) - A cost-sharing program available to forest landowners who have a multiresource forest stewardship plan. Practices include cost-sharing assistance for the enhancement of forest recreation, fisheries, wildlife, and timber production and the protection of soil and water, wetlands, riparian zones, and rare and endangered species.
SITE INDEX - A relative measure of forest site quality based on the height (in feet) of the dominant trees at a specific age (usually 25 or 50 years, depending on rotation length). Site index information helps estimate future returns and land productivity for timber and wildlife.
SITE INDEX: Height of a tree at a specified index or base age. Used as an indicator of site quality.
SITE PREPARATION - Preparing an area of land for planting, direct seeding, or natural reproduction by burning, chemical vegetation control, or by mechanical operations such as disking, bedding, scarifying, windrowing, or raking.
SITE PRODUCTIVITY CLASS: A classification of forest lands in terms of inherent capacity to grow crops of industrial wood. The class identifies the potential growth in merchantable cubic feet/acre/year and is based on the age of culmination of mean annual increment of fully stocked natural stands. Classes are as follows:
- 1: 225 or more cubic feet per acre
- 2: 165 to 224 "
- 3: 120 to 164 "
- 4: 85 to 119 "
- 5: 50 to 84 "
- 6: 20 to 49 "
- 7: less than 20 "
SITE TREE QUALITY: A classification of sample tree according to how well the tree reflects the productive potential of the site.
SIZE DOWN WOODY MATERIAL: Dead twigs, branches, stems, and boles of trees and brush that have fallen and lie on or above the ground but within 1.8, (6 feet) meters of the ground.
- Small Twigs: Small twigs are defined as those fuel pieces which have a cross section diameter of less than 1/4 inch (6mm) at the point of intersection with the sampling plane.
- Large Twigs: Large twigs are defined as those fuel pieces which have a cross section diameter of between .25 and .99 inches (6 and 25mm) inclusive at the point of intersection with the sampling plane.
- Branches: Branches are defined as those fuel pieces with a cross section diameter of between 1.0 and 2.99 inches (25 and 75mm) inclusive at the point of intersection with the sampling plane.
- Large Fuel: Branches or pieces 3.0. (75mm) or larger at the point
of intersection with the sampling place. The actual diameter is usually recorded for each
large piece selected.
SLASH - (a) Tree tops, branches, bark, or other residue left on the ground after logging or other forestry operations. (b) Tree debris left after a natural catastrophe.
SNAG CONDITION: A description of the deterioration of a standing dead tree.
- Stage 1. Branches, twigs, bark intact.
- Stage 2. Loose bark, secondary branches gone.
- Stage 3. Bole clean.
- Stage 4. Top broken.
- Stage 5. Top broken, bole decomposed.
SOFTWOOD (CONIFER) - A tree belonging to the order Coniferales. Softwood trees are usually evergreen, bear cones, and have needles or scalelike leaves. They include pine, spruces, firs, and cedars.
SOIL BULK DENSITY: The mass of undisturbed or disturbed dry soil per unit bulk volume. The bulk volume is determined before drying to a constant weight at 105 c. The value is expressed in grams per cubic centimeter (g/cc).
SOIL COMPACTION: A physical change in soil properties that results in a decrease in porosity and an increase in soil bulk density and soil strength.
SOIL COVER: The type of cover on the soil surface.
- Soil covered by live vegetation
- Soil covered by litter
- Soil covered by rock
- Soil covered by pavement
- Soil not covered - exposed.
SOIL DISPLACEMENT: The movement of the forest floor (litter, duff and humus layers) and surface soil from one place to another by mechanical forces such as a blade used in piling or windrowing. Mixing of surface soil layers by discing, chopping, or bedding operation, are not considered displacement.
SOIL DRAINAGE CLASS: Natural soil drainage refers to the rapidity and extent of the removal of water from the soil, in relation to incoming water. This is especially true of water by surface runoff and by flow through the soil to underground spaces. Soil drainage, as a condition of the soil, refers to the frequency and duration of periods when the soil is free of saturation or partial saturation. The seven classes are:
- Excessively Drained: Soils with very high and high hydraulic conductivity and low water holding capacity. They are not suited for crop production unless irrigated.
- Somewhat Excessively Drained: Soils with high hydraulic conductivity and low water holding capacity. Without irrigation only a narrow range of crops can be grown and yields are low.
- Well Drained: Soils with intermediate water holding capacity. They retain optimum amounts of moisture, but they are not wet close enough to the surface or long enough during the growing season to adversely affect yields.
- Moderately Well Drained: Soils that are wet close enough to the surface for long enough that planting or harvesting operations are adversely affected unless artificial drainage is provided. Moderately well drained soils, commonly have a layer with low hydraulic conductivity, wet state relatively high in the profile, additions of water by seepage, or some combination of these conditions.
- Somewhat Poorly Drained: Soils that are wet close enough to the surface or long enough that planting or harvesting operations are markedly restricted unless artificial drainage is provided. Somewhat poorly drained soils commonly have a layer with low hydraulic conductivity, wet state high in the profile, additions of water through seepage, or a combination of these conditions.
- Poorly Drained: Soils commonly wet at or near the surface during a considerable part of the year. Poorly drained conditions are caused by a saturated zone, a layer with low hydraulic conductivity, seepage, or a combination of these conditions.
- Very Poorly Drained: These soils are wet to the surface most of the time. These soils are wet enough to prevent the growth of important crops (except rice) unless artificially drained.
SOIL EROSION TYPE: Soil erosion is the process of removal of soil material by running water, wind or gravitational creep. Factors that affect soil erosion are climate, nature of the soil, slope, vegetation and cultivation practices. Classes of erosion by water are:
- Class 1: Soils that have lost some of the original A horizon but on the average less than 25 percent of the original A horizon or of the uppermost 20 cm if the original A horizon was less that 20 cm thick. Throughout most of the area the thickness of the surface layer is within the normal range of variability of the non eroded soil. Scattered spots amounting to less than 20 percent of the area may be modified appreciably. Evidence for class 1 erosion includes (1) a few rills, (2) accumulation of sediment at the base of slopes or in depressions, (3) scattered spots where the plow layer contains material from below the original plow layer, and (4) evidence of formation of widely spaced deep rills or shallow gullies without consistently measurable reduction in thickness or other change in properties between the rills or gullies.
- Class 2: Soils that have lost on the average 25 to 75 percent of the original A horizon or of the uppermost 20 cm if the original A horizon was less than 20 cm thick. Throughout most cultivated areas of class 2 erosion the surface layer consists of a mixture of the original A horizon and material from below. Some areas may have intricate patterns ranging from non eroded spots to spots where all of the original A horizon has been removed. Where the original A horizon was very thick, little or no mixing of underlying material with the original A horizon may have taken place.
- Class 3: Soils that have lost on the average 75 percent or more of the original A horizon or of the uppermost 20 cm if the original A horizon was less than 20 cm thick. In most areas of class 3 erosion, material below the original A horizon is exposed at the surface in cultivated areas. The plow layer consists entirely or largely of material that was below the original A horizon. Even where the original A horizon was very thick, at least some mixing of underlying material with the original A horizon has generally taken place.
- Class 4: Soils that have lost all of the A horizon or the uppermost 20 cm if the original A horizon was less than 20 cm thick plus some or all of the deeper horizons throughout most of the area. The original soil can be identified only in spots. Some areas may be smooth, but most have an intricate pattern of gullies.
Classes of erosion by wind:
- Class 1: Soils that have lost some of the original A horizon but on the average less than 25 percent of the original A horizon or of the uppermost 20 cm if the original A horizon was less that 20 cm thick. Throughout most of the area the thickness of the surface layer is within the normal range of variability of the non eroded soil. Scattered spots amounting to less than 20 percent of the area may be modified appreciably. Evidence for class 1 wind erosion includes (1) a surface layer coarser in texture than in the non eroded areas nearby, (2) low mounds of sand and perhaps coarser particles, and (3) lower depressions, or swales, from which soil material has been blown.
- Class 2: Soils that have lost on the average 25 to 75 percent of the original A horizon or of the uppermost 20 cm if the original A horizon was less than 20 cm thick. Throughout most cultivated areas of class 2 wind erosion the surface layer consists of a mixture of the original A horizon and material from below. Most class 2 areas consist of an intricate pattern of eroded and non eroded spots and some spots of deposition.
- Class 3: Soils that have lost on the average 75 percent or more of the original A horizon or of the uppermost 20 cm if the original A horizon was less than 20 cm thick. In most areas of class 3 wind erosion, material below the original A horizon is exposed at the surface; in places enough of the original surface layer remains that it can be identified. The removal of material is generally not uniform. A few blow-out areas may be included.
- Class 4: Soils that have lost all the A horizon or the uppermost 20 cm if the original A horizon was less than 20 cm thick plus some or all of the deeper horizons throughout most of the area. The original soil can be identified only in spots. Depressions where all of the material has been blown out are common. Areas between blowouts may be buried by soil from the blowouts.
SOIL MAP UNIT: A named portion of a landscape shown by a closed delineation and symbol on a soil map.
SOIL PUDDLING: A physical change in soil properties due to shearing forces that alters soil structure and porosity. Puddling occurs when the soil is at or near liquid limit.
SOIL STRUCTURE: Structure is described by grade, class and type. Terms are used to describe natural aggregates in the soil called peds in contrast to clods caused by disturbance, fragments by rupture of peds, and concentrations by local concentrations of compounds that irreversibly cement the soil grains together. Classes are as follows:
- Granular, approximately spherical with no accommodation of faces to surrounding peds.
- Platy, with vertical dimension small with regard to horizontal dimensions; faces accommodate with those of adjacent peds.
- Prismatic, without rounded caps, vertical faces well defined and with angular vertical length relatively long with respect to horizontal dimensions; faces accommodate with those of adjacent peds.
- Columnar, with rounded caps, otherwise similar to the prismatic.
- Angular blocky, blocklike with all 3 dimensions of the same order of magnitude, faces flattened, most vertices sharply angular; faces accommodate with those of adjacent peds.
- Subangular blocky, similar to angular blocky but both rounded and flattened faces occur with many rounded vertices.
- Structureless - massive or single grain.
SOIL TEXTURE: The relative proportions of clay, silt, and sand (less than 2mm in diameter). Clay particles are the smallest, silt particles are intermediate, and sand particles are the largest. Loams contain various mixtures of the three basic particle sizes. Rock fragments in the soil can modify textural names depending on size and amount. Stones and boulders on the surface can affect use and coverage should be estimated.
SOIL TAXONOMIC UNIT: A soil class at any categorical level in the U.S. system of soil taxonomy e.g. order, suborder, great group, subgroup, family, or series.
SOIL TEXTURE - The feel or composition of the soil (sand, silt, or clay) as determined by the size of the soil particles.
SOIL TYPE - Soils that are alike in all characteristics, including texture of the topsoil. Soil maps and information on site index, erodibility, and other limiting properties are available from your county Soil Conservation Service offices.
SPECIES - A group of related organisms having common characteristics capable of interbreeding. Loblolly and Virginia pine are common species that can be interbred.
STAND - An easily defined area of the forest that is relatively uniform in species composition or age and can be managed as a single unit.
STAND AGE: The mean age of the dominant and codominant trees in the stand.
STAND CONDITION: A classification of forest stands based upon the age of maturity and structure of the overstory and understory.
- Old-Growth Stands: Ecosystems distinguished by old trees and related structural attributes. Old growth encompasses the later stages of stand development which typically differ from earlier stages in a variety of characteristics that may include tree size, accumulations of large dead woody material, number of canopy layers, species composition, and ecosystem function. The age at which old growth develops and the specific structural attributes that characterize old growth will vary widely according to forest type, climate, site conditions and disturbance regime. For example, old growth in fire-dependent forest types may not differ from younger forests in the number of canopy layers or accumulation of down woody material. However, old growth is typically distinguished from younger growth by several of the following structural attributes:
- Large trees for species and site.
- Wide variation in tree sizes and spacing.
- Accumulations of large-size dead standing and fallen trees that are high relative to earlier stages.
- Decadence in the form of broken or deformed tops or bole and root decay.
- Multiple canopy layers.
- Canopy gaps and understory patchiness.
- Young-Growth Stand: Any forested stand not meeting the definition of old growth.
STAND HISTORY: The kind of disturbance (prior to plot establishment) on the sample location.
STAND ORIGIN: The apparent source of vegetation on the location - natural or artificial regeneration.
STAND SIZE CLASS: A classification of land based on the stocking of all live vegetation of various sizes.
- Nonstocked with vegetation
- Land less than 10-percent stocked with trees, but having vegetation.
- Grass-Forb Stands: Stands less than 10 percent stocked with trees. Shrubs less than 40 percent crown canopy.
- Shrub Stands: Stands less than 10 percent stocked with trees. Shrubs greater than 40 percent crown canopy.
- Stocked with trees.
- Seedling-Sapling Stands: Stands at least 10 percent stocked with live trees of all sizes, of which half or more of the stocking consists of seedling and/or saplings (trees < 5.0" d.b.h.).
- Poletimber Stands: Stands at least 10 percent stocked with live trees of which half or more of the stocking is in trees, 5.0 inches d.b.h. and larger, and in which the stocking of poletimber (softwoods-5.0 to 8.9 inches d.b.h., hardwoods-5.0 to 10.9 inches d.b.h.) exceeds the stocking of sawtimber (trees larger than poletimber).
- Sawtimber Stands: Stands at least 10-percent stocked with live trees of which half or more of the stocking is in trees 5.0 inches d.b.h. and larger, in which the stocking of sawtimber trees is at east equal to the stocking of poletimber trees.
STAND STRUCTURE: A description of the distribution and representation of STAND AGE and STAND SIZE classes within a stand.
- Even-Aged Single Storied: Theoretically, stands in which all the trees are one age. In actual practice, these stands are marked by an even canopy of uniform height characterized by intimate competition between trees of approximately the same size. The smaller trees are usually tall spindly members of the stand that have fallen behind their associates. The greatest number of stems are in a diameter class represented by the average of the stand; there are fewer trees in the classes above and below this mean. A single even canopy characterizes the stand. The greatest number of trees are in a height class represented by the average height of the stand; there are substantially fewer trees in height classes above and below this mean. The ages of the trees usually do not differ by more than 20 years.
- Even-Aged Two-Storied: Stands composed of two distinct canopy layers, such as, an overstory and understory sapling layer possibly from seed tree and shelterwood operations. This may also be true in older plantations where tolerant hardwoods may become established as management intensity decreases (burning and other means of understory control). Two relatively even canopy levels can be recognized in the stand. The frequency distribution of trees by height class tends to be bimodal. Understory or overtopped trees are common. Neither canopy level is necessarily continuous or closed, but both canopy levels tend to be uniformly distributed across the stand. The average age of each level differs significantly from the other.
- Uneven-Aged: Theoretically, these stands contain trees of every age on a continuum from seedlings to mature canopy trees. In practice, uneven-aged stands are characterized by a broken or uneven canopy layer. Usually the largest number of trees is in the smaller diameter classes. As trees increase in diameter, their numbers diminish throughout the stand. Many times, instead of producing a negative exponential distribution of diminishing larger diameters, uneven-aged stands behave irregularly with waves of reproduction and mortality. Consider any stand with 3 or more structural layers as uneven-aged. Logging disturbance (examples are selection, diameter limit and salvage cutting) will give a stand an uneven-aged structure.
- Mosaic: At least two distinct size classes are represented and these are not uniformly distributed, but are grouped in small repeating aggregations, or occur as stringers less than 120 feet wide, throughout the stand. Each size class aggregation is too small to be recognized and mapped as an individual stand. The aggregations may or may not be even-aged.
STAND YEAR OF ORIGIN: Year the stand was planted or created.
STEWARDSHIP FOREST - A privately owned forest tract that exhibits integrated forest management to protect and enhance wildlife, timber, recreation, natural beauty, and soil and water quality.
STOCKING - A description of the number of trees, basal area, or volume per acre in a forest stand compared with a desired level for balanced health and growth. Most often used in comparative expressions, such as well-stocked, poorly stocked, or overstocked.
STOCKING PERCENT: The amount of live trees on a given area in relation to what is considered the optimum. A calculation using either the total number of trees, total basal area, or total volume per unit area divided by the optimum total number of trees, optimum total basal area or optimum total volume for a particular species and management objective, expressed as a percent. The classes are 10 percent intervals with an overall range from non-stocked to 100% stocking, relative stocking basis. Data in the form of absolute stocking (0-167 percent basis) should be reduced to relative stocking by dividing by a factor of 1.67.
STREAMSIDE MANAGEMENT ZONE (SMZ) - An area adjacent to a stream in which vegetation is maintained or managed to protect water quality. The width depends on slope, but 50 feet is the normal minimum. Trees may be removed from SMZs as long as the stream bed is not disrupted and sufficient vegetation is left to protect water quality.
STREAM CHANNEL-BANK ANGLE: A measure of the angle formed by the downward sloping streambank as it meets the more horizontal stream bottom.
STREAM ORDER: A numbering scheme used to characterize the relative position of stream channels within a drainage. Given a map, the first-order streams are those which have no tributaries. The second-order streams are those which have as tributaries only first-order channels. The third-order stream is formed when two second-order channels come together, etc.
STREAM SHADE COVER: The percent of shade covering a stream or lake shore water surface averaged for the day.
STREAM TYPE: Alpha-numeric identification given to reoccurring stream channel types based on measurable morphological features.
STREAM WIDTH: The width of streams or rivers. Stream or River - means a natural water course.
STREAMBANK UNDERCUT: A measure of the furthest point of protrusion of the bank to the furthest undercut of the bank. Streambank undercut provides cover for fish and may be conducive to producing high biomass of fish. Undercut is a good indicator of how successfully streambank are protected under alternative and uses, such as livestock grazing and road building.
STREAMFLOW: Measure of the volume of water passing a given point in a stream channel at a given point in time. Streamflow is a function of depth, width and velocity of water in a channel. Changes in streamflow affect the available habitat for fish spawning or rearing. Streamflow can be determined using a number of methods. Expressed in cubic feet/sec. or cubic meters/sec.
STUMPAGE - The value or volume of a tree or group of trees as they stand uncut in the woods (on the stump).
STUMP HEIGHT: The vertical distance from the ground on the uphill side to the top of the stump on cut trees. Vertical distance from the ground to a stump height set by study objectives or local utilization practice for uncut trees.
SUBDIVISION: See LAND LOCATION (GLO).
SUCCESSION - The natural sequence of plant community replacement beginning with bare ground and resulting in a final, stable community in which a climax forest is reached. Foresters, wildlife biologists, and farmers constantly battle ecological succession to try to maintain a particular vegetative cover.
SUCCESSIONAL DISKING or MOWING - A wildlife enhancement practice in which a disk harrow or rotary mower is used to knock down existing vegetation every 1 to 3 years to promote the regrowth of annuals, legumes, forbes, and perennials.
SULFATE: A measure of sulfate concentration. Expressed as mg/l of SO4.
SUPPRESSED TREES: Trees or shrubs with crowns receiving no direct light either from above or from the sides, and that will not respond to release. Usually crowns are entirely below the general level of the canopy.
SURFACE EROSION: The detachment and transport of individual soil particles by wind, water, or gravity.
SUSPENDED SEDIMENT: Sediment which remains in suspension in water for a considerable period of time without contact with the bottom. Sediment content is measured in the Laboratory and reported as parts per million or milligrams per liter.
SUSTAINED YIELD - Management of forestland to produce a relatively constant amount of wood products, revenue, or wildlife.
SWEEP -Gradual bend in a standing tree or in a log, pole, or piling.