S | Lexicon of Forestry


Saddle planting: See hole planting
Safari park: (Syn Wildlife park) A safari park is a large enclosed area of land where wild animals wander relatively freely and people pay to drive around and observe them.
Safe bearing capacity: The workable bearing capacity of the soil, which is considered for design. (See also: Factor of Safety; UBC)
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. 
Saline Alkali soils/ Saline Sodic Soils: These are soils containing both soluble salts and exchangeable sodium. TheElectrical Conductivity (ECe) @ 25 OC is = 4. The Exchangeable sodium percent (ESP) is ≥ 15. pH seldom above 8.5 (Depending upon dominance of salts or sodium). They are converted into non-saline alkali soils by leaching out of soluble salts. (See also: Non-Saline Alkali Soils)
Saline Soil/ White Alkali Soil: Saline soils are soils containing sufficient amount of soluble salts. Its electrical conductivity (ECe) @ 25OC is ≥ 4 millimohs/cm, Exchangeable sodium percent (ESP) is < 15, pH is < 8.5, and Chlorides and Sulphates are the basic anions.
Salvage: The exploitation of trees that are dead, dying, or deteriorating (e.g., because overmature or materially damaged by fire, wind, insects, fungi, or other injurious agencies) before their timber value becomes economically worthless.
Sample: A small collection from some larger population, about which a woodland owner wishes information.
Sample tree: A representative or average-sized tree, chosen for detailed measurement of condition, size, growth, or quality.
Sanctuary: It is a place or area where wild indigenous animals are kept in protection so that they breed and are thus preserved. Shooting or hunting is prohibited in this area. A sanctuary is established by a notification and it can be put an end to by a similar procedure.
Sand: A substance consisting of fine loose grains of rock or minerals, usually quartz fragments, found on beaches, in deserts, and in soil, sometimes used as a building material. Size: 0.05mm – 2mm.
Sanitation cutting: The removal of dead, damaged, or susceptible trees or their parts, or of vegetation that serves as an alternate host for crop-tree pathogens, to prevent or control the spread of pests or pathogens.
Sanitation measures: The removal of dead, damaged, or susceptible trees or their parts, or of vegetation that serves as an alternative host for crop-tree pathogens, to prevent or control the spread of pests or pathogens. 
Sap: A watery liquid containing mineral salts, sugars, and other nutrients that circulates through the conducting tissues of a plant
Sapling: A general term for a young tree no longer a seedling but not yet a pole, about 1-2 m high and 2-4 cm in dbh, typically growing vigorously and without dead bark or more than an occasional dead branch. Also, a young tree having a diameter at breast height greater than 1 cm but less than the smallest merchantable diameter. 
Sapling stand: A stand of trees whose average dbh is between 1 and 4 inches.
Saprophyte: Any plant that depends on dead plant or animal tissue for a source of nutrition and metabolic energy, e.g., most fungi (molds) and a few flowering plants,
Sapwood: The light-colored wood that appears on the outer portion of a cross section of a tree. Composed of dead cells; serves to conduct water and minerals to the crown. A minimum of 1 in of sapwood is required on all poles to ensure proper absorption of preservatives. Also termed “xylem.”
Satellite nursery: See field nursery
Satisfactorily stocked: See stocking: satisfactorily stocked
Savannah or savanna: Grassland with scattered trees, fairly common in the central plains, especially of the U.S. before development.
Saw log: A log large enough to be sawn into lumber.
Sawlog tree: A tree at least 11 inches dbh and suitable for conversion to lumber. Sometimes, trees 11 to 14 inches dbh are called small sawlog trees, and trees larger than 18 inches dbh are called large sawlog trees.
Sawmill: A plant at which logs are sawed into salable products, including all the machinery and buildings necessary for the operation of the plant.
Saw timber: Trees that yield logs suitable in size and quality for the production of lumber.
Sawtimber stand: A stand of trees whose average dbh is greater than 11 inches.
Scaffolding: Framework to support workers: a temporary framework of poles and planks that is used to support workers and materials during the erection, repair, or decoration of a building; The temporary structure constructed to support a safe working platform for workmen and materials required during operation is called Scaffold and method of construction is called Scaffolding.
Scale: The estimated sound volume of a log or group of logs in terms of a given log rule or formula; used to estimate the sound volume of a log or group of logs. (See: log rule).
Scale: Any of the small flat bony or horny overlapping plates that cover the bodies of fish and some reptiles and mammals; covering of butterfly wing: a small structure that overlaps others to form the covering of the wings of butterflies and moths
Scale stick: A graduated stick for measuring the diameters and contents of logs; both measures are stamped on the stick.
Scalp: To physically remove the sod or surface layer of debris, to expose mineral soil for tree planting.
Scalping: Paring off low and surface vegetation, with most of its roots, to expose a weed-free soil surface, generally preparatory to sowing or planting thereon. If done by chemicals, termed chemical screefing. 
Scarify: 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.
Scarification: Loosening the topsoil of open areas or breaking up the forest floor to assist the germination of natural seed from either standing trees or slash or to promote the occurrence of coppice or sucker growth.
Schoolmarm: Logger’s slang for a tree with one or more trunks.
Scion: An aerial plant part, often a branchlet, that is grafted onto another root-bearing plant (stock, rootstock).
Scorch: Appearing as if tissues were burned by heat; usually affecting marginal portions of leaves.
Screefing: See scalping
Scribe: A tool for marking trees or round timber by scoring the outer surface.
Scrub: See brush
Scrub control: See brushing
Sealed-bid sale: A timber sale, usually offered through a consulting forester, in which buyers submit secret bids.
Season: To dry lumber, either in the open or in a dry kiln.
Seasonal grazing: The grazing of an area only during a certain period or periods of the year, roughly corresponding to one or more of the seasons. (SAF)
Seasoning: The process of drying (curing) lumber or other forms of wood to improve its properties: natural (air or underground drying) or artificial (kiln drying, electrical drying, oil drying, etc.).
Secondary species: A species of inferior quality and/or size, and of lesser silvicultural value, associated with the principal species. (cf. accessory species).
Second growth: A second forest that develops after harvest of the original, natural forest. In the Pacific Northwest, these forests also are often called young growth stands.
Section: A unit of land area equal to 640 acres, 6,400 sq chains, I sq mile, or 80 chains on each side.
Sectional area/ Cross-sectional area: The area of the cross section of the bole. This parameter is very important in forestry. The sectional area at breast height is used in many relationships and is called basal area. (See Basal area)
Sedges: Plants of the genus Carex, which includes over 1,500 species; sedges look similar to grasses. 
Sediment: [Mid-16th century. < Latin sedimentum “settling” < sedere “sit”] 1. Settled matter at bottom of liquid: material, originally suspended in a liquid that settles at the bottom of the liquid when it is left standing for a long time 2. Eroded material: material eroded from preexisting rocks that is transported by water, wind, or ice and deposited elsewhere
Sedimentation: The deposition or settling of soil particles suspended in water.
Seed: A plant part produced by sexual reproduction that contains the embryo and gives rise to a new individual. In flowering plants it is enclosed within the fruit.
Seed bank: A place in which seeds of rare plant or obsolete varieties are stored, usually vacuum-packed and under cold conditions, to prolong their viability.
Seed bearer: 1. Any tree producing seed. 2. Any tree retained to provide seed for natural regeneration, e.g., during seed cuttings. 
Seedbed: In natural plant reproduction, the soil or forest floor on which seed falls; in nursery practice, a prepared area in which seed is sown.
Seed coat: The protective covering of a seed from a flowering plant (syn Testa)
Seed collection area: A forest stand that exhibits good characteristics of growth, form, and vigor and that is not managed for cone production, but from which seed is collected, usually at the time of harvest. 
Seed cutting: Removing trees in a mature stand so as to effect permanent opening of its canopy (if there was no preparatory cutting to do this) and so provide conditions for securing regeneration from the seed of trees retained for that purpose; the first of the shelterwood cuttings under a shelterwood system. 
Seeding: A reforestation method by sowing seed aerially or by hand. Often done immediately after harvest so that a new forest is started the next growing season. Aerial: Broadcast seeding of seeds or seed pellets from aircraft. Broadcast:   The sowing of seeds more or less evenly over a whole area on which a forest stand is to be raised. Direct:   The artificial systematic sowing of seeds by manual or mechanical means in an area on which a forest stand is to be raised. Drill:   The sowing of seeds in shallow furrows across a whole area on which a forest stand is to be raised. A practice more common in nurseries. Natural:   The dispersal by natural agents of seeds from standing trees in proximity to a regenerating area or from slash scattered over that area. Seeds may be dispersed by wind, birds, mammals, gravity, or flowing water or be released by fire from serotinous cones. Row:   The sowing of seed in deep furrows simultaneously with disc trenching for site preparation. Sheltered spot:   The sowing of seeds under small conical shelters of translucent or opaque, bio- or photo-degradable material as a means of stabilizing the microsite and improving germination. Spot:   The sowing of seeds within small, cultivated, or otherwise-prepared patches, many of which are distributed over a whole area on which a forest stand is to be raised. 
Seeding felling: See seed cutting
Seeding lath: A device, commonly of wood, for obtaining uniformly spaced drills in a seedbed and aiding the even distribution of hand-sown seed in them.
Seedling: 1. A small tree grown from seed. Usually the term is restricted to trees less than 2 in d.b.h. 2. A young tree, grown from seed, from the time of germination to the sapling stage, having a diameter at breast height of no more than 1 cm and a height of no more than 1.5 m.
Seedling blight: A fungal disease that attacks rice seedlings
Seedling Forest: (See: High Forest)
Seed orchard: A plantation of trees, assumed or proven genetically to be superior, that has been isolated so as to reduce pollination from genetically inferior outside sources, and intensively managed to improve the genotype and produce frequent, abundant, and easily harvestable seed crops. A clonal seed orchard is established by setting out clones as grafts or cuttings; a seedling seed orchard is established from selected seedling progenies.
Seed origin: See provenance
Seed pellet: See pelleting
Seed production area: A forest stand identified as a good source of seed and in which individual trees are evaluated for desired characteristics. Unwanted trees and competing trees are removed to promote cone production. Seed is collected periodically from standing trees or by felling sections as required.
Seed source: The locality where a seed lot was collected usually defined on an eco-geographic basis by distance, elevation, precipitation, latitude, etc. If the stand from which collections were made was exotic, the place where its seed originated is the original seed source. (cf. provenance).
Seed spot: (syn. Seedspot) A prepared, limited space, e.g., a small, cultivated patch, within which (tree) seeds are sown.
Seed stand: Any stand used as a source of seed. 
Seed trap: A device for catching the seeds falling on a small area of ground, from trees or shrubs. Used for determining the amount of seedfall and the time, period, rate, and distance of dissemination.
Seed tree: A mature tree left uncut to provide seed for regeneration of a harvested stand.
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-tree method: A method of regenerating a forest stand in which all trees are removed from the area except for a small number of seed-bearing trees that are left singly or in small groups. If these are retained for increment as well as seed, termed a reserve cutting. The objective is to create an even-aged stand. 
Seed-tree removal: See final cutting
Seed-tree system: See seed-tree method
Seed year: 1. A year in which a given species produces a large seed crop over a sizable area. Some species of trees produce seeds irregularly. 2. The year in which a tree species produces, either as an individual or a crop, an adequate amount of seed; applies to any species but particularly to those with irregular or infrequent seed production. Many periodic seeders produce heavy (bumper) seed crops during their seed years. 
Seed zone: Areas of similar climatic and elevational conditions, used to specify where tree seed was collected and where trees from such seed are most likely to be successfully grown.
Seiche: A free or standing wave oscillation of the surface of water in an enclosed basin that is initiated by local atmospheric changes, tidal currents, or earthquakes. Similar to water sloshing in a bathtub
Seismic belt: An elongated earthquake zone, for example, circum-Pacific, Mediterranean, Rocky Mountain. About 60 percent of the world’s earthquakes occur in the circum-Pacific seismic belt.
Seismic constant: In building codes dealing with earthquake hazards, an arbitrarily-set acceleration value (in units of gravity) that a building must withstand.
Seismicity: Earthquake activity.
Seismic: Of or having to do with earthquakes.
Seismic sea wave: A tsunami generated by an undersea earthquake.
Seismic zone: A region in which earthquakes are known to occur.
Seismogram: A written record of an earthquake, recorded by a seismograph.
Seismograph: An instrument that records the motions of the Earth, especially earthquakes.
Selection: Choosing individuals with desired qualities to serve as parents for the next generation. 
Selection differential: The average phenotypic value of the selected individuals, expressed as a deviation from the population mean. 
Selection forest: Forest treated and managed under the selection system. 
Selective grazing: The preferential and sometimes excessive grazing of certain plants in mixed pasture.
Selection harvest: 1. The harvest of all individual trees or small groups at regular intervals to maintain an uneven-aged forest. Selection harvests are used to manage species that do not need sunlight to survive. (See also Reproduction methods) 2. Annual or periodic cutting of trees chosen individually or by groups, in an uneven-aged stand, in order to recover the yield and develop a balanced uneven-aged stand structure, while providing the cultural measures required for tree growth and seedling establishment. The cuts are usually a mix of regeneration cuts and improvement cuts. Selection cutting is not the same as selective cutting.
selection method: A method of regenerating a forest stand and maintaining an uneven-aged structure by removing some trees in all size classes either singly or in small groups or strips.
Selection thinning: See thinning: selection
Selective cutting: See high grading
Selective harvesting: See high grading
Selective logging: See high grading
Self-pruning: The inherent ability of a tree species to shed dead branches at their junction with the live stem.
Self-thinning: Tree mortality from the effect of the competition arising between trees on the same site.
Senescence: Aging of tissues; growing old.
Sericulture: Shortening of French sériciculture < Latin sericum “silk,” form of sericus < Greek sērikos]. Sericulture, or silk farming, is the rearing of silkworms for the production of raw silk. Although there are several commercial species of silkworms, Bombyx mori is the most widely used and intensively studied. 
Silkworm Larva and Cocoon. The silkworm larva pupates within a cocoon made of one continuously wound silken thread. When straightened, each thread can reach lengths of 900 m (3,000 ft). Silkworms have been cultivated for their silk in Asian countries for centuries.
Serotinous: Coming late; particularly applied to plant species or individuals with cones that remain on the tree without opening for one or more years (e.g., Pinus contorta and Pinus banksiana).
Sessile: Attached or fastened; incapable of moving from place to place.
Seta (plural = setae): Slender, hairlike or bristly projections arising from the epidermal layer on any part of the body of an insect.
Severance felling: A cleared strip cut through a stand so as to develop a wind-firm edge before making any fellings.
Severance tax: A tax paid on forest products after they are cut.
Sexual stage: Reproductive stage of the life cycle of an organism.
Shade tolerance: The capacity of a tree or plant species to develop and grow in the shade of and in competition with other trees or plants. See tolerance.
Shagreen: Rough, untanned leather: rough untanned leather with a grainy surface, made from the hide of various animals and often dyed green
Shake: 1. A lengthwise separation of wood (usually caused by wind) that usually occurs between and parallel to the growth layers. 2. A thin section split from a bolt of wood and used for roofing or siding.
Shark-fin barrel: A mechanical site preparation device consisting of pairs of metal barrels on which are welded steel fins along opposing spiral lines; this conformation causes circular motion and lateral scalping when the barrels are pulled over land to be planted or seeded.
Shear: 1. In Christmas tree culture, to shape and trim back the branches to make dense foliage and give tree a conical shape. 2. In felling, a mechanical device that pinches trees off at the stump. natural (air or underground drying) or artificial
Shearing: 1. A method of harvest using mechanical shears. 2. The shaping of a tree crown, particularly with respect to Christmas trees or ornamentals, by removing part of the leader and/or the ends of live branches to comply with a desired crown form. 3. A method of site preparation in which all standing material is removed at ground level using a shear blade attached to a large tractor.
Shelterbelt: A wind barrier of living trees and/or shrubs, drying, electrical drying, oil drying, etc.) maintained to protect farm fields or homesteads. (Syn. belt, windbreak).
Shelterwood: See reproduction methods.
Shelterwood compartment system: See shelterwood cutting: uniform shelterwood system

Shelterwood harvest/ cutting: The harvest of all mature trees in an area in a series of two or more cuts, leaving enough trees of other sizes to provide shade and protection for forest seedlings. Irregular shelterwood system :  Harvest cutting in which opening of the canopy is irregular and gradual; generally in groups, with the final cutting often in strips; regeneration is natural; regeneration interval is long, often up to half the rotation, and the resultant crop considerably uneven-aged and irregular. Strip shelterwood system :  A shelterwood system in which regeneration cuttings are carried out on fairly wide strips, generally against the prevailing wind, and progress rapidly; regeneration is mainly natural, regeneration interval short, and the resultant crop fairly even-aged and regular. Uniform shelterwood system :  A shelterwood system in which the canopy is opened fairly evenly throughout the regeneration area; regeneration is mainly natural, though it may be supplemented artificially; regeneration interval is fairly short and the resultant crop more or less even-aged and regular.
Shoot pruning: Cutting away undesirable shoots to favor survival and growth of selected shoots.
Shoring: The temporary support provided to an unsafe structure or to a structure undergoing alterations in a shore, and method is Shoring. 
Shotholes: Small holes in a leaf caused by feeding activity and giving the appearance of injury via a shotgun.
Shrinkage: The contraction of wood caused by drying growth stands. Shrinkage values are usually expressed as a percentage of specific dimensions (or the volume) of the wood when green.
Shrub: A woody perennial plant (lives more than I year) that differs from a perennial herb by its woody, persistent stems, and from a tree by its low stature and branches that start from the base.
Sidecast: Earth and other material generated by road building and deposited on the downhill side of the road.
Side cutting: See box pruning
Side-hole planting: See hole planting
Sign: The actual presence of the causal organism in association with the disease symptoms.
Silkworm: Moth larva that spins silk: a yellowish caterpillar, the larva of an Asian moth that feeds on mulberry leaves and is a commercial source of silk. Latin name: Bombyx mori
Sill: [Old English syll “foundation of a wall” < Germanic] 1.  Window ledge: a ledge below a window, especially one on the inside of a building 2. Bottom of frame: the horizontal part at the bottom of a window or door frame
Silt: One of the basic soil particles having a grain size of 0.002mm – 0.05mm
Silver thaw: A weather phenomenon in which great quantities of ice collect on trees and other vegetation, often causing much breakage.
Silvics: The study of the life history and general characteristics of forest trees and stands, with particular reference to locality factors as a basis of silviculture.
Silvicultural decision model: A computer model or system that permits the simulation and possibly prediction of the interaction of such factors as site class, access, managed-stand volume, and logging costs to assist in decisionmaking regarding silvicultural practices in individual stands.
Silvicultural efficacity: The capacity of a herbicide indirectly to promote positive growth responses in crop trees. 
Silvicultural regime: A series of stand tending (thinning, pruning, etc.) treatments applied after regeneration to achieve a specific stand management objective.
Silvicultural rotation: The rotation through which a species maintains satisfactory growth and reproduction on a given site.
Silvicultural system: A process that applies silvicultural practices, including tending (thinning, pruning, etc.), harvesting, and replacement, to a stand in order to produce a crop of timber and other forest products. Note: the system is named by the cutting method with which the regeneration is established.
Silviculture: [Late 19th century. < French < Latin silva “a wood” + French culture “cultivation”] 1. The study, cultivation, and management of forest trees; the art and science of raising, tending and harvesting forest crop. 2. The art and science of producing and tending a forest; the theory and practice of controlling forest establishment, composition, growth, and quality of forests to achieve the objectives of management.
Silvicultural system: A planned programme of Silvicultural principles or treatments throughout the life of a stand.
Silvipasture: An agroforestry system where trees and livestock are produced together.
Simple coppice system: A coppice system in which the crop is clearcut and regenerated by stool shoots, stump sprouts, or root suckers, giving even-aged stands; rotation is relatively short. 
Single-moldboard plough: A plough with one moldboard, generally right-hand, turning the whole furrow slice to one side of the furrow.
Single-tree selection method: A method of regenerating uneven-aged stands in which individual trees of any size are removed more or less uniformly throughout the stand.
Site: [14th century Latin situs “place, position]. 1. An area of land, especially with reference to its capacity to produce vegetation as a function of environmental factors (climate, soil, biology, etc); an area considered in terms of its environment, particularly as this determines the type and quality of the vegetation the area can carry. 2. A land area based on its climatic, physiographic, edaphic, and biotic factors that determine its suitability and productivity for particular species and silvicultural alternatives.
Site amelioration: See site improvement
Site capability: The mean annual increment in merchantable volume which can be expected for a forest area, assuming it is fully stocked by one or more species best adapted to the site, at or near rotation age. Expressed in cubic metres per hectare per year.  (cf. productivity).
Site class:  1. A grouping of similar site indexes that indicates relative productivity. The common system for the Chir pine region includes three site classes, with 1 (I) the most productive and 3 (III) the least.
Site classification: Application of analytical techniques based on macroclimate, soil, land form, and vegetation, to predict yield.
Site factor: An ecological term referring to a physical or biological parameter used to describe and distinguish sites.
Site improvement: Modifications to a given site in order to improve growing conditions for a specific species or mixture of species. 
Site index: A measure of forest site quality based on the height (in ft) that dominant trees will reach at a given age. For Douglas-fir, this is commonly “pressed as either a 50- or 100-year site index. 2. A measure of the relative productive capacity of a site for a particular spp. The average height or top height at a give age is generally basis for classification. (BCFT)
Site map: A map showing the distribution of the different forest or stand types which have a bearing on management with information aabourt their composition, age classes, etc. (BCFT)
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 quality: The productive capacity of a site; usually expressed as volume production of a given species per unit area (cubic metres per hectare) or per unit of time (cubic metres per year).
Size classes: Ranges in tree sizes representing stages in the development of a tree or stand.
Skeleton: [Late 16th century. Via modern Latin < Greek skeleton (sōma) “dried up (body)” < skellein “dry up”] the rigid framework of interconnected bones and cartilage that protects and supports the internal organs and provides attachment for muscles in humans and other vertebrate animals
Skeletonizer(s): Insects which consume leaf tissue, often from the lower side of the leaf, leaving the upper epidermis and vascular tissues intact.
Skidder: A rubber-tired machine with a cable winch or grapple used to drag logs out of the forest.
Skidding:  The process of dragging logs from the woods to a landing, usually applied to ground-based operations. A similar term, used especially with cable or aerial logging systems, is “yarding.”
Skid road, skid trail:  A pathway over which logs are skidded.
Skyline logging: A type of cable logging in which the mainline is stationary and a carriage moves up and down it, collecting turns of logs.
Slash: The undesirable residue after logging, via. Branches, barks, chunks, unutilizable logs, uprooted stumps, and broken uprooted trees left on the area; also may be the accumulations of debris after wind or fire. (SAF)
Slab: The exterior portion of a log removed in sawing timber.
Slash: Tree tops, branches, bark, and other debris, left after a forest operation. The process of cutting down undesirable vegetation.
Slash chopper: See brush chopper
Slash disposal: The treatment or handling of slash, particularly so as to reduce fire or insect hazard.
Slashing: A form of cleaning. 
Slash removal: See slash disposal
Sleeve planting: See tube planting
Slit planting: Prying open a cut made by a spade, mattock, or planting bar (termed bar planting), inserting a young tree, and then closing the cut on the latter by pressure. Note: Making standing T-shaped cuts, generally with a special tool, is sometimes termed T-notching.
Slot: The smallest unit in Irrigated Layout. Its dimensions are: depth 1 ft, breadth 1 ft. The space between two slots is 6 ft. A trench (See Trench) waters a slot. In plains, slots are made on north side.
Smut: The smuts are fungi, mostly Ustilaginomycetes (of the class Teliomycetae, subphylum Basidiomycota), that cause plant disease.
Snag: A dead tree that is still standing. Snags provide important food and cover for a wide variety of wildlife species.
Snagging: Removing or cutting away snags, on land or in water.
Sociology: [Mid-19th century. < French sociologie < Latin socius “companion”] study of society: the study of the origin, development, and structure of human societies and the behavior of individual people and groups in society
Sod-forming grass: A grass that spreads by creating new plants from existing plants by running roots across or under the ground (stolons or rhizomes, respectively), creating a dense turf. Also called spreading grass. Contrast with clump-forming grass (also called bunchgrass), in which single plants get larger over time but do not create new plants.
Soffit: bottom surface: the underside of a structural component of a building, e.g. the underside of a roof overhang or the inner curve of an arch
Soft snag: A snag composed primarily of wood in advanced stages of decay and deterioration, particularly in the sapwood portion. 
Softwood: 1. Cone-bearing or aril-bearing trees with needle or scale-like leaves belonging to the botanical group Gymnospermae. Pinus roxburghii, Cedrus deodara are softwoods. Also, stands of such trees and the wood produced by them. 2. A forest type in which 76-100% of the canopy is softwood. 
Soil: [13th century. Via Anglo-Norman, “piece of land” < Latin solium “seat,” by association with solum “ground, soil”] top layer of land: the top layer of most of the Earth’s land surface, consisting of the unconsolidated products of rock erosion and organic decay, along with bacteria and fungi; (from Latin “Solum” which means “ground/ soil”) A natural body on surface of earth, in which plants grow, composed of organic and inorganic matter. It consists of fragmented and partly weathered rocks and minerals, organic matter, water and air in varying proportions. It has more or less distinct layers due to influence of climate and living organisms.
Soil bank: Land retired from crop production and planted with soil-building plants under a program that provides subsidies for the retired land.
Soil Formation: Soil formation is the process by which rocks are broken down into progressively smaller particles and mixed with decaying organic material. Bedrock begins to disintegrate as it is subjected to freezing-thawing cycles, rain, and other environmental forces (I). The rock breaks down into parent material, which in turn breaks into smaller mineral particles (II). The organisms in an area contribute to soil formation by facilitating the disintegration process as they live and adding organic matter to the system when they die. As soil continues to develop, layers called horizons form (III). The A horizon, nearest the surface, is usually richer in organic matter, while the lowest layer, the C horizon, contains more minerals and still looks much like the parent material. The soil will eventually reach a point where it can support a thick cover of vegetation and cycle its resources effectively (IV). At this stage, the soil may feature a B horizon, where leached minerals collect.
Soil horizon: A soil horizon is a distinctive soil layer such as topsoil or subsoil. Collectively, the horizons make up what is called a Soil Profile.
Soil moisture: The relative amount of water in the soil; usually applied to upper levels of soil, occasionally to humus layer
Soil profile:  A vertical section of soil showing the nature and thickness of the various horizons, often used in soil classification. Soil generally consists of visually and texturally distinct layers, which can be summarized as follows from top to bottom: O) Organic matter: Litter layer of plant residues in relatively undecomposed form.  A) Surface soil: Layer of mineral soil with most organic matter accumulation and soil life. This layer eluviates (is depleted of) iron, clay, aluminum, organic compounds, and other soluble constituents. When eluviation is pronounced, a lighter colored “E” subsurface soil horizon is apparent at the base of the “A” horizon. A-horizons may also be the result of a combination of soil bioturbation and surface processes that winnow fine particles from biologically mounded topsoil. In this case, the A-horizon is regarded as a “biomantle”. B) Subsoil: This layer accumulates iron, clay, aluminum and organic compounds, a process referred to as illuviation. C) Parent rock: Layer of big unbroken rocks. This layer may accumulate the more soluble compounds.
Soil scarification: See scarification
Soil Science (Pedology): (From Greek “Pedo” means “soil”) It the scientific study of soil, its properties, formation and geographic distribution and the classification of soil types
Soil series: Groupings of soils with similar profile characteristics
Soil stabilization: Any process which aims at increasing and maintaining resistance of soil.
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.
Somatic embryogenesis: A process by which clones are produced by cell growth from a seed embryo.
Sowing: See seeding
Sowing brick: A prepared, sometimes fertilized, block or ball of loam, peat, plastic foam, etc., into which one or more seeds are pressed, so that, on planting out, the emergent seedling can have a better start in an unfavorable environment.
Spacing: 1. The distance between trees in a plantation, a thinned stand, or a natural stand. 2. (see thinning: spacing)
Spar.  A pole, tower, or tree used in cable logging to raise the mainline off the ground.
Species: A group of related organisms having common characteristics capable of interbreeding. Loblolly and Virginia pine are common species that can be interbred.
Species (of trees): Trees having very similar genetic makeup, so that they freely interbreed and have common characteristics. In common language, a “kind” or “variety.” Each species is identified by a scientific name that consists of a genus portion and then a species portion (Pinus gerardiana).
Specimen or specimen plant: A plant that is grown in relatively open ground with little competition and therefore develops an unnaturally (in most cases) broad spread and dramatic form. Contrast with masses, drifts, thickets, or groves of plants, in which individual specimens intermingle with each other and may even be hard to distinguish from each other.
Spiegel Relaskop (or Relascope): The Spiegel Relaskop, also known as a Relaskop, is a sophisticated instrument that can be used to measure stand basal area and tree height and diameter at any point up a tree bole. In conjunction with other equipment, the Relaskop can be used in the estimation of distance (range) to an object and the number of trees/ha. It is relatively expensive. Heights can be read from an internal scale if the user is 20, 25 or 30 m from the tree. However, there are a number of scales visible and novice users are often confused by the apparent reading complexity. 
Spike top: A tree with a dead top, usually a mark of declining vigor.
Spore: A specialized structure consisting of one or few cells and serving any or all of the following three functions: (i) reproduction, (ii) dissemination. (iii) survival.
Sporophore: A spore-producing or supporting structure.
Spot planting: Setting out young trees in small, prepared patches. 
Spot scarifier: A scarification implement enabling site preparation on patches.
Spot seeding: See seed spot
Spot weeding: Removing undesirable vegetation from patches.
Spray: [Early 17th century. < Middle Dutch sprayen “sprinkle”] discharge liquid from pressurized container: to disperse a liquid in the form of fine particles, or apply a liquid in this form to the surface of something
Spray gun: See paint gun
Spreader: Any substance, solid or liquid, that, when added to a pesticide, herbicide, liquid fertilizer, or fire retardant, enables it to spread better over the surfaces on which it is deposited.
Spreading grass: Grass that spreads by creating new plants from existing plants by running roots across or under the ground (stolons or rhizomes, respectively), creating a dense turf. Also called sod-forming grass. Contrast with bunchgrass (also called clump-forming grass), in which single plants get larger over time but do not create new plants.
Spring-tine cultivator: An implement designed to loosen the soil surface by the action of spring-loaded retractible teeth.
Springwood: 1. The less dense, larger-celled, first-formed wood of an annual growth ring. Spud: A hand tool used in stripping bark from felled trees. staff compass. (See compass).
Sprout: A young tree developed directly from the base, stump, or root of another tree. Relatively common among hardwoods; with conifers, typical only of redwoods. (Syn. Sucker).
Spud: A hand tool used in stripping bark from felled trees.
Squirrel: [14th century. < Anglo-Norman esquirel, literally “little squirrel” < Latin sciurus < Greek skiouros < skia “shadow” + oura “tail”] small bushy-tailed rodent: a small rodent that has a long bushy tail, lives in trees, and eats nuts and seeds. Family: Sciuridae
Stadium (plural = stadia): The period of time between two successive molts.
Staff compass:  See compass.
Stage: One of the successive principal divisions in the life cycle of an insect, e.g., egg, nymph, larva, prepupa, pupa, adult.
Staghead: Death of limbs and main branches of a tree in the upper crown, giving the appearance of antlers.
Stagnant: Describes condition of stands whose growth and development have all but ceased due to poor site and/or excessive stocking. 
Stair case: A series of steps which provide access from one floor to another in a stair and the part of the building accommodating the stair is known as stair case.
Stanchion: Upright supporting pole: a vertical pole, bar, or beam used to support something
Stand: 1. An aggregation of trees occupying a specific area and uniform enough in composition (species), age, and arrangement to be distinquishable from the forest on adjoining areas. 2. A group of forest trees of sufficiently uniform species composition, age, and condition to be considered a homogeneous unit for management purposes.
Stand age: See age
Standard: A tree selected to remain standing, after the rest of the stand has been felled over a younger or a new crop, for some special purpose, e.g., shelter, seeding, production of a special quality or size of timber.
Stand composition: See composition
Stand condition: The descriptive measurement of a stand by the criteria of composition, health, age, size, volume, or spatial arrangement. 
Stand density: A quantitative measure of tree stocking, expressed either relatively as a coefficient, taking normal numbers, basal area, or volume as unity, or absolutely, in terms of numbers of trees, totals basal area, volume, per unit area.
Stand density index: Any index for evaluating stand density such as those of Curtis, Mulloy, Reinecke.
Stand density management diagram: A two-dimensional graph showing the logarithmic relationship between declining mean stem frequency and increasing mean tree size, as mean stand diameter and dominant height increase in pure even-aged stands.
Stand development: The growth of a stand through its various developmental stages – from seedling or coppice through thicket, sapling, and pole to the tree stage, i.e. to maturity, and finally to overmaturity. 
Stand establishment: See establishment
Stand improvement: See timber stand improvement
Standing crop: See crop
Stand model: A mathematical model that forecasts the development of a forest stand, usually in terms of mean stand attributes, e.g., mean diameter, height.
Stand table: A summary table showing the number of trees per unit area by species and diameter classes, for a stand or type. The data may also be presented in the form of a frequency distribution of diameter classes.
Stand type: A collection of stands within a forest types which are sufficiently similar to require some treatment and planning or produce the same type of produce. (See also Forest Type).
Stand, type of.  Mixed: A stand in which more than 25% of the trees in the main crown canopy are of a species other than the major species. Pure. A stand in which at least 80-90% of the trees in the dominant and codoininant crown classes are of a single species.
State forest: Forest owned by the state. (See: Crown Forest)
Status year: The year to which a description of regeneration status applies.
Stem: The trunk of a tree. stocking. The number of trees in a forest. Usually expressed as trees per acre or some relative measure (well stocked/fully stocked, overstocked, under-stocked).
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.
Stewardship Incentive Program (SIP): A cost-sharing program available to forest landowners who have a multi-resource 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.
Stipple: Pigmented spots up to a few millimeters in diameter, often on the upper surface of leaves.
Stocked: Area where stocking standards have been met.
Stocked quadrat: In regeneration surveys, a quadrat having at least one live tree seedling or regrowth. The criteria for what constitutes a “stocked” area vary with species, site, country, etc.
Stocking: 1. A more or less subjective indication of the number of trees as compared to the number for best results; A quantitative term which designated the relative occupation of the site by trees. 2. 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. Fully stocked: Productive forest land stocked with trees of merchantable species. These trees by number and distribution or by average dbh, basal area, or volume are such that at rotation age they will produce a timber stand that occupies the potentially productive ground. They will provide a merchantable timber yield according to the potential of the land. The stocking, number of trees, and distribution required to achieve this will be determined from regional or local yield tables or by some other appropriate method. Ideally stocked:  See normally stocked. Irregularly stocked:  See partially stocked. Nonstocked :  Productive forest land that lacks trees completely or that is so deficient in trees, either young or old, that at the end of one rotation, the residual stand of merchantable tree species, if any, will be insufficient to allow utilization in an economic operation. Normally stocked :  Productive forest land covered with trees of merchantable species of any age. These trees, by number and distribution, or by average dbh, basal area, or volume, are such that at rotation age they will produce a timber stand of the maximum merchantable timber yield. This yield must satisfy the site potential of the land as reported by the best available regional or local yield tables. For stands of less than rotation age, a range of stocking classes both above and below normal may be predicted to approach and produce a normal stocking at rotation age and may, therefore, be included. This is because greater or lesser mortality rates will occur in over- or understocked stands as compared with those in a normal stand. NSR (not sufficiently or not satisfactorily restocked or regenerated) :  Inadequate stocking. Productive forest land that has been denuded and has failed partially or completely to regenerate naturally or to be artificially regenerated.The regeneration must contain a minimum number of well-established, healthy trees that are free-from-noncrop-competition and sufficient to produce a merchantable timber stand at rotation age. Optimally stocked: See normally stocked. Overstocked :  Productive forest land stocked with more trees of merchantable species than normal or full stocking would require. Growth is in some respect retarded and the full number of trees will not reach merchantable size by rotation age according to the regional or local yield or stock tables for the particular site and species. Partially stocked :  Productive forest land stocked with trees of merchantable species insufficient to utilize the complete potential of the land for growth such that they will not occupy the whole site by rotation age without additional stocking. Explicit definition in stems per hectare, crown closure, relative basal area, etc., is locally or regionally defined and is site-specific. Satisfactorily stocked :  Productive forest land that has been regenerated naturally or artificially to at least a minimum number of well-established, healthy trees of merchantable species that are free-from-noncrop-competition and sufficient to produce a merchantable timber stand at rotation age.
Stocking control: The regulation and, more particularly, the limitation of seedling populations by natural, or direct or indirect artificial factors.
Stocking density: A measure of the proportion of the area actually occupied by trees.
Stocking guide: Reference level for the optimum proportion of an area actually occupied by trees, expressed in terms of stocked quadrats or percentage of canopy closure.
Stock table: A summary table showing the volume of trees per unit area by species and diameter classes, for a stand or type.
Stolons: Surface roots that travel laterally and root at the joints, growing new plants. An example is ground ivy (Glechoma hederacea, also called creeping Charlie).
Stool: 1. Silviculture: A living stump capable of producing sprouts or shoots. 2. Propagation: A living stump maintained to produce cuttings, layers, etc.
Stool shoot: See sprout
Storied high forest: A crop of trees in which the canopy can be differentiated into one or more layers, the dominant species in natural forest generally differing in each layer. 
Story: A horizontal stratum or layer in a plant community; in forests, appearing as one or more canopies. A forest having more than two stories is called multistoried. A forest having one story (the main story) is called single-storied. A forest having two stories (the overstory and the understory) is called two-storied.
Stratification: 1. Division of a forest, or any ecosystem, into separate layers of vegetation that provide distinct niches for wildlife. See canopy, understory, and herbaceous vegetation. 2. The storage of seeds under defined conditions of environment (temperature, moisture, gas exchange, medium, etc.) for specified periods in order to overcome passive or active inhibition of germination. The term may also apply to physical or chemical treatment of seed designed to achieve the same end.
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.
Stretcher: Stone with long edge facing out: a brick or stone laid in a wall so that its longer edge forms part of the face of the wall. A stretcher provides longitudinal strength to the walls (See also header) (Pic at header)
Strip-and-group system: A modification of the shelterwood strip system in which, in addition to the normal uniform seed cutting, groups of advance growth are freed both in the strip and closely ahead of it, along with further group cuttings to initiate regeneration; regeneration is mainly natural; regeneration interval is relatively short and the resultant crop fairly even-aged and regular. 
Strip application: See band application
Strip burning: 1. A method of controlled burning practiced on slopes. The area is burnt in successive strips beginning on the uphill side. (SAF) 2. Controlled burning on a strip to provide a barrier against subsequent forces fires and a basis for backfiring.
Strip cropping: Crop planting in which strips of heavy-rooted plants are alternated with loose-rooted plants which serve as barriers to wind and water erosion. 
Strip cutting: Removal of the crop in strips in more than one operations, generally for encouraging natural regeneration or protecting fragile sites. Considered to be a variation of clearcutting.
Strip felling: See strip cutting
Strip planting: Setting trees, generally in two or more parallel lines, in a long narrow area of land that has been wholly or partially cleared.
Strip shelterwood: See shelterwood cutting
Strip spraying: See band application
Strip thinning: See thinning: row
Structure: The distribution of trees in a stand or group by age, size, or crown classes (e.g., all-aged, even-aged, uneven-aged, regular, and irregular structures).
Stub: The broken or cut base of a branch projecting from a tree stem.
Stumpage: The value of timber as it stands uncut in the woods; in a general sense, the standing timber itself. Can also denote price paid for this timber.
Stumpage price: The price paid for standing forest trees.
Stump blade: See brush blade
Stump extraction: A general term for the process of pulling out stumps by force.
Removal of stumps may be done to facilitate scarification or to prevent infection from diseased root systems.
Stump height: The distance from the ground to the top of the stump. Good logging practice dictates that stumps be as low as possible (preferably as low as 12 inches) to reduce waste, to minimize visual impact on the logging site, and to promote resprouting of trees.
Stump sprout: See sprout
Stump treatment: Application of herbicides to or near hardwood stumps to prevent coppicing. Also, fungicides or paint can be applied to prevent fungal infection.
Stylet: A small, stiff, needlelike tube inserted into a food source to obtain liquid food.
Sub-compartment: Temporary sub-division, differentiated for separate treatment. Commonly designated by small letters, eg a, b, c,etc
Subdominant: See crown class: intermediate
Subduction: The process in which one lithospheric plate collides with and is forced down under another plate and drawn back into the Earth’s mantle.
Sub-esophageal Ganglia: The subesophageal ganglion of insects is composed of three pairs of fused ganglia. It controls the mouthparts, the salivary glands and certain muscles. The subesophageal ganglion sits beneath the esophagus. It is connected to the supraesophageal ganglion, which sits above the esophagus.
Subsidiary crop: See secondary species
Subsoil: Soil beneath topsoil: the compacted soil beneath the topsoil (Pic at Soil Horizon)
Subspecies: A category used to classify plants and animals whose populations are distinct, e.g. in distribution, appearance, or feeding habits, but can still interbreed
Succession: 1. A unidirectional process in which a plant community replaces another in a predictable manner until a final community is established which is more stable and not susceptible to any change. The final community is called climax and the whole process is called Succession. 2. The natural replacement of one plant (or animal) community by another over time in the absence of disturbance. 3. 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. 3. The gradual supplanting of one community of plants by another, the sequence of communities being termed a sere and each stage seral.
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.
Succession, types of.  Primary: Plant succession on newly formed soils or surfaces, “posed for the first time, that have never borne vegetation. Secondary.   Plant succession following the destruction of a part or all of the original vegetation.
Sucker: A sprout from the lower portion of a stem, especially from the root.
Sucker knot: A knot associated with a limb growing nearly parallel to the main stem. Sucker knots are not permitted on poles because they funnel water into the pole, promoting decay even if treated. A relative measure of amount of stocking on a forest area, compared with other areas.
Sucking insects: Insects that insert their mouthparts into plant tissues and withdraw nutrients and fluids through stylets.
Summerwood: The denser, later-formed wood of an annual growth ring. The cells are smaller, with thick cell walls, so they usually give the layer a darker color than that of the springwood.
Sunscald: Death of cambial tissue on one side of a tree, caused by exposure to direct sunlight. suppressed tree. (See overtopped).
Sunto Clinometer: A small, light, robust and inexpensive instrument for measuring height. An internal scale normally indicates percentage slope. Height above or below the operator is calculated by multiplying the percentage slope by the distance from the tree. Thus, there is no fixed distance for common use.

Some people experience difficulties sighting through the Suunto. You must look into the Suunto while simultaneously sighting along side it to see the tree. Particular care is needed if the operator suffers from astigmatism.
Superstructure: The part of a building above its foundations
Suppressed trees: (See: Overtopped tree; Crown classes)
Suppression: The process whereby certain trees, shrubs, etc., in a community become weakened, essentially through the competition of the neighbors but also by extension, through human intervention and selective browsing by livestock. 
Surface of earth: The value given is the depth below the surface of the mean spheroid. The mean spheroid is a uniform approximation to the true shape of the Earth. No adjustment is made to the depth due to any differences between the true Earth and the mean spheroid. For example, the minimum depth that will be given is 0 km, even though a quake directly under Mount Everest (elevation 8,850 m) could legitimately have a depth of -6 km and still be 2 km underground. On the other hand, a depth of 10 km would actually be more than 1 km above the ocean floor of Challenger Deep (11,033 m below sea level) in the Marianas Trench of the Pacific Ocean.
Surface runoff: Water that moves over the ground surface. With the exception of established drainage channels, uncommon on undisturbed forest land.
Surface waves: Waves that move over the surface of the Earth. Rayleigh waves and Love waves are surface waves.
Suscept: Any organism that can be attacked by a biotic pathogen.
Suspension bridges: A bridge with a roadway that is suspended from cables anchored by towers at either end and often supported by structures at regular intervals. Pic at bridge.
Sustainable development: Sustainable development in forestry expands the principle of sustained timber yield by including wildlife and fish habitats, watersheds and hydrological cycles, as well as gene pools and species diversity, to ensure that the use of forest today does not damage prospects for its use by future generations.
Sustainable forestry: Management of forested area in order to provide wood products in perpetuity, soil and watershed integrity, persistence of most native species and maintenance of highly sensitive species or suitable conditions for continued evolution of species.
Sustained yield: 1. The material that a forest can yield annually or periodically in perpetuity. (IFR) 2. As applied to a policy, method or plan of management (sustained yield management), implies continuous production with the aim of achieving, at the earliest practical time and at the highest practical level, an approximate balance b/w net growth and harvest, either by annual or somewhat longer periods. (SAF)
Swamp: To clear the ground of underbrush, fallen trees, and other obstructions, to facilitate such later operations as logging or surveying.
Swarming: It means climbing using arms and legs or group of insects in flight
S wave: Shear, secondary, rotational, tangential, equivoluminal, distortional, transverse, or shake wave. These waves carry energy through the Earth in very complex patterns of transverse (crosswise) waves. These waves move more slowly than P waves, but in an earthquake they are usually bigger. S waves cannot travel through the outer core because these waves cannot exist in fluids, such as air, water or molten rock. (Pic at Core)
Sweep: A tree defect characterized by a gradual curve in the main stem.
Swell-butted: Describes a tree greatly enlarged at the base. (Syn. bottle-butted, chum-butted).
Symptom: Visible or measurable manifestation that an organism is diseased; a change in the organism itself.

Systematic thinning: See thinning: mechanical
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Corrections and Suggestions are most welcome. Please use the comment section for feedback. If you see any missing terminology or any updated one or any latest term please use the comment section for the purpose. Also, if you have any image or data related to any above terminologies, don’t forget to mail me at tulaib_javid@yahoo.com.
Regards
Naeem Javid Muhammad Hassani
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