Salvage cut – Harvesting trees that have been killed or are in danger of being killed by insects, disease, fire, wind, flood or other unexpected cause to recover their economic value.
Sanitation cut – The harvesting or destruction of trees infected or highly susceptible to insects or diseases to prevent spreading the pest to remaining trees in the area.
Sapling – A small tree, often defined as being between 1 and 4 inches DBH.
Sawlog – A log large enough to produce a sawn product—usually at least 10 to 12 inches in diameter, 8 feet long, and solid.
Sawtimber – Standing trees large enough to produce sawlogs.
Scalping – Removing a patch or strip of sod to expose mineral soil in preparation for planting trees.
Scarification – Churning the soil surface to expose mineral soil and uproot vegetation to prepare a seedbed for natural or artificial seeding.
Seedbed – The ground surface on which tree seeds will naturally fall or be artificially seeded.
Seed cut – A harvest in a shelterwood system that is designed to encourage the growth of desirable seed-producing trees, create a good seedbed for germination, and eliminate undesirable trees, shrubs, and herbaceous plants that may produce seed.
Seed tree – A tree left standing after a timber harvest as a source of seed for reproducing a new stand.
Seed tree harvest – A harvest in which all trees are removed from the harvest area except for a few scattered trees that provide seed to establish a new stand. Produces an evenaged stand.
Seeding – Scattering tree seeds over an area by hand or machinery to establish a new stand of trees.
Seedling – A tree, usually defined as less than 1 inch in DBH, that has grown from a seed (in contrast to a root sucker or stump sprout).
Selection harvest – A harvest in which individual trees or small groups of trees are cut at periodic intervals (usually 8 to 15 years) based on their physical condition or degree of maturity. Produces an uneven-aged forest.
Self-prune – The ability of a tree to naturally lose its lower branches as the tree ages, thus enabling knot-free wood to grow on the stem.
Shade tolerance – Relative ability of a tree species to reproduce and grow under shade. Tree species usually are classified in descending order of shade tolerance as very tolerant, tolerant, intermediate, intolerant, or very intolerant.
Shelterwood harvest – A harvest in which trees are removed in a series of two or more cuttings to allow the establishment and early growth of new seedlings under the partial shade and protection of older trees. Produces an even-aged forest.
Shrub – A perennial plant with a persistent woody stem(s) and low-branching habit that usually grows less than 10 feet tall. Contrast with tree.
Silviculture – The art, science, and practice of establishing, tending, and reproducing forest stands of desired characteristics based on knowledge of species characteristics and their environmental requirements.
Site – A contiguous (connected) area with a more or less uniform combination of biological, climatic, and soil conditions.
Site index – A measure of site quality for growing trees based on the total height that dominant and codominant trees are expected to grow in a given time period, usually 50 years in the Lake States. Trees are expected to grow taller on good sites than on poor ones in the same time period.
Site preparation – A set of practices (for example, brush clearing, chemical vegetation control, and prescribed burning) that improve a seedbed or suppress competing vegetation, to increase the chances for successfully establishing a new stand of trees.
Skid trail – Usually a temporary, unimproved roadway that enables skidders or forwarders to transport logs from the interior of a woodland to a landing.
Slash – Residue such as tree tops, branches, bark, and unmerchantable wood left on the ground after logging, pruning, or other forest operations.
Snag – A standing dead tree.
Softwoods – See conifer.
Soil texture – The particle composition of a soil based on the proportion of sand, silt, and clay.
Species – One of the basic units of biological classification—a group of organisms capable of interbreeding and producing fertile offspring.
Species composition – The mix of tree species occurring together in a stand.
Stand – A group of trees occupying a given area and sufficiently uniform in species composition, tree size distribution, stocking, and soil characteristics so as to be distinguishable from the adjoining forest. If 80 percent or more of the trees are of the same species, it is a pure stand. Otherwise, it is a mixed species stand.
Stand density – See stocking.
Stocking – A measure of the degree of crowding of trees in a stand, also known as stand density. Commonly expressed by the number of trees per acre or percentage of crown cover.
Stocking chart – A chart usually based on one or more tree species, number of trees per acre, and tree stem diameters that shows the best stocking for timber growth, considering the species present and stem diameters.
Stratify seed – Subjecting seed to cold temperatures and regulating moisture for a period of time to break seedcoat dormancy and improve seed germination.
Structural board – A wood panel made from chips or flakes that have been formed into a panel by heat, pressure, and sometimes an adhesive. Frequently used in construction for underlayment on floors, roofs, and walls.
Stumpage – The dollar value of a standing tree or group of trees.
Stump sprout – A young tree that has grown from a dormant bud on a tree stump. It is an exact genetic replica of the original tree.
Succession – The process by which one plant community is gradually replaced by another due to environmental conditions and species characteristics, such as shade tolerance.
Sucker – See root sucker.
Suppressed – See crown classification.
Sweep – A C-shaped curvature in a tree stem or log.