Glossary of Key Terms and Abbreviations

A-K | L-R | S-Z

Note: Terms listed and defined in this glossary are in boldface. Terms which may be of particular interest to the reader in a given context, but are not listed in the glossary, are in italics.

Landing: Also called log deck or yard. Place in or near the forest where logs are gathered for further processing or transport.

Latex: Milky substance, extracted from some species of rubber trees, used in the manufacture of paper and glue. Latex is used to make strong, durable, weather-resistant paper; latex glue is used to make self-seal envelopes.

lbs/in: Pounds-force per square inch. A measure of bursting strength.

Leaching: Downward movement of a soluble material through the soil as a result of water movement.

Lightweight paper: Paper manufactured in weights below the minimum basis weight considered standard for that grade. High-brightness, high-opacity paper used by publishers of magazines, directories, Bibles, hymnals, reference books and catalogs.

Lignin: Complex organic material that binds together fibers in trees and woody plants.

Linerboard: Paperboard made from unbleached kraft pulp, recycled fibers, or a combination of the two, used to line or face corrugated board (on both sides) to form corrugated boxes and other shipping containers.

Lint: Paper fragments or dust on the sheet. Excess lint can contaminate copiers and printers.

Lithography: Process of using a flat-surfaced plate that carries an image which is transferred to a blanket, then to paper. Also known as offset printing

Logging debris: Also called slash. Accumulation of woody material, such as large limbs, tops, cull logs and stumps, that remains as forest residue after stem-only timber harvesting (as opposed to whole-tree harvesting). Logging debris is typically removed, displaced into piles, chopped, or burned during site preparation.

Logging residues: In this book, the portion of logging debris that is merchantable and that is removed from the site to be chipped for pulpwood or other uses. Logging residues typically make up a small fraction of total pulpwood supply.

Machine clothing: Paper-machine felt and wire.

Machine coating: Coating applied while paper or board is still on the paper machine.

Makeready: All work done to set up a press for printing.

Market pulp: Pulp sold on the open market; virgin market pulp is air-dried and wrapped; deinked market pulp can be sold in air-dried or wet-lapped (partially dry) form.

Materials recovery facility (MRF): Facility that upgrades recycable materials for resale to manufacturers or by separating, cleaning and baling incoming materials.

Mature forest: Stage in forest development in which the original dominant trees in the forest canopy begin to die and fall, creating canopy gaps that allow understory trees to grow, and providing coarse woody debris on the forest floor. Corresponds roughly to understory regeneration stage. Sometimes used more broadly to include old-growth forest.

Mechanical pulp: Pulp produced by shredding pulpwood logs and chips using mechanical energy via grindstones (groundwood pulp) or refiners (thermomechanical pulp).

Merchantable: Commercially valuable; merchantable timber has potential for sale as sawtimber, pulpwood, fuelwood or other wood products.

Mineral soil: Soil free of organic matter that contains rock less than 2" in maximum dimension.

Mixed paper: An inclusive, "catch all" or "what's left over" category for a wide variety of recovered paper blends. "Mixed paper" can refer to the commingled remnants of paper boxmaking or printing operations, or to office waste collected by haulers who removed some contaminants at a transfer station, or paper collected from households. The physical properties and intrinsic value of the paper are different in each case.

Moisture content: Percentage of moisture, by weight, found in a sheet of paper or paperboard, e.g., generally ranging from 5% to 8% in copy paper.

Multi-ply: Paper or paperboard sheet made of two or more layers.

Municipal solid waste (MSW): Includes durable goods, nondurable goods and containers and packaging that have served their useful life and have been discarded, plus food scraps and yard trimmings from residential, commercial, and institutional sources. Strictly defined, MSW does not include construction and demolition debris, sludge, combustion ash and industrial process wastes.

Natural community: Discrete assemblage of interacting plants and animals, often referred to by their dominant plant associations: e.g., longleaf pine-wiregrass savanna; oak-hickory forest; beech-maple forest.

Natural disturbance: Naturally occurring events that disturb the forest by killing or felling one or more trees. Natural disturbance regimes -- the typical natural disturbance patterns in a given region and forest type -- vary by scale (individual tree mortality vs. wildfire over hundreds of acres), severity (light disturbance of the forest soil in a low-intensity fire vs. landslides that remove massive amounts of soil and organic matter, along with trees and vegetation), and frequency. Natural disturbance regimes typically determine the dominant forest types (which in turn help determine natural disturbance regimes): e.g., longleaf pine-wiregrass savannas in the southeast are maintained by and help to propagate frequent low-intensity ground fires.

Natural regeneration: Method for replacing trees removed through harvesting, in which new trees sprout from cut stumps or roots, or germinate from seeds present in the upper soil layer. May be used in both even-aged and uneven-aged silvicultural systems.

Newsprint: Relatively inexpensive groundwood paper made from mechanical pulp, thermomechanical pulp (TMP) or secondary fiber; used extensively by newspaper and directory publishers. Basis weights range from 30 to 35 lbs.

Non-commercial species: Tree species typically of small size, poor form or inferior quality, that normally do not develop into trees suitable for industrial wood products.

Non-industrial private landowners: Private timberland owners other than forest-products companies and their subsidiaries.

Nutrients: Chemical elements required by plants for their growth and existence. Various nutrients are used for countless basic functions, such as manufacturing proteins and plant cells. The best-known plant nutrients include nitrogen and phosphorus. Low levels of key nutrients in soils can substantially limit plant growth and productivity. Nutrients may be added to soils in fertilizer to make up for inherent soil deficiencies.

OCC: Old corrugated containers.

Off-machine coating: Also known as conversion coating. Process of coating paper on a separate machine from the paper machine..

Office Paper: Wastepaper generated by offices, including stationery and computer paper.

Office pack: A more detailed definition of what is allowed and not allowed in sorted office paper developed by individual deinking mills for use by their recovered paper suppliers.

Offset paper: Paper made specifically for use on offset printing presses, characterized by strength, cleanliness, pick-resistance and relative freedom from curl. Offset paper must be relatively impervious to water.

Offset printing: Also called offset lithography or photo-offset. Indirect printing process that uses lithographic plate on which images or designs are ink-receptive; the rest of the plate is water-receptive. Ink is transferred from the plate to a rubber-blanketed cylinder that transfers (off-sets) the image to the paper.

Old-growth forest: The fourth and final stage of stand development, following

mature forest , in which the forest canopy is generally composed of scattered remaining trees that assumed dominance following natural disturbance along with newly dominant, shade-tolerant trees. Other characteristics of old-growth forest may include accumulated coarse woody debris, snags and canopy gaps created by fallen trees. Because of these features, and the presence of an understory, old-growth forests generally exhibit complex stand vegetation, and provide habitat for many species. Development of old-growth forest generally takes from 100 to 200 years, with variation depending on forest type. The last remaining sizable area of old-growth forest in the contiguous U.S. lies in the Pacific Northwest; only a few small and isolated patches of old-growth remain in eastern forests. However, as a stage in stand development, old-growth forest could also develop in eastern forests (and was present in presettlement forests).

OMG: Old magazines.

ONP: Old newspapers.

Opacity: Also called show-through. Degree to which one is unable to see through the sheet; measured by the amount of light that transmits through a sheet. Opacity is a function of the type and amount of fiber, basis weight, sheet compaction, void volume and the inclusion of various fillers in the paper. Paper can have a maximum opacity of 100%, in which no light is transmitted at all. For duplexing and double-sided printing, opacity is an important characteristic.

Oven-dried ton/metric ton of pulp (ODTP/ODMTP): The moisture content of oven-dried pulp is zero. Air-dried pulps have about a 10% moisture content

Overstory: See forest canopy.

Ozone (O3): Powerful oxidizing agent used in bleaching processes to remove lignin and colored substances from pulp. Ozone is formed by passing electricity through a stream of oxygen gas. It is a pollutant in smog that results from the reaction of nitrogen oxides and volatile organic compounds with sunlight.

Paper machine: Machine on which pulp is made into paper; a sheet is formed,, dried and wound on rolls. (See cylinder machine and fourdrinier machine.)

Paper: Medium formed primarily from cellulose fibers in a water suspension, bound together with additives and formed on a wire machine. General term designating one of the two broad classifications of paper; the other is paperboard.

Paperboard: Comparatively thick, strong paper used to make such products as packaging, corrugated boxes, folding cartons and set-up boxes.

Particulates: Small particles that are dispersed into the atmosphere during combustion.

Perennial stream: Watercourse that flows throughout most of the year in a well-defined channel.

Persistence: Ability of a pesticide to remain active over a period of time.

Pesticides: Chemicals used in silviculture to control unwanted insects (insecticides) or unwanted vegetation (herbicides).

PIA: Printing Industry of America.

Picking: Fibers in the paper that tend to pull away from the surface during the printing process. Picking occurs when the tack or pull of the ink is greater than the surface strength of the paper. An increase in surface pick resistance is commensurate with an increase in bonding strength. Pick resistance is important in office papers that are run through the reprographic process in which excessive linting can cause impairment of copies.

Plantation : Planted stand of trees.

Ply: One layer of paper or paperboard that makes up a multi-layer (multi-ply) sheet.

Point: One thousandth of an inch equals one point; used to denote the caliper measurement of paper and paperboard.

Polyethylene: Thermoplastic film applied to paper to make it suitable for packaging; also applied to foodboard for liquid resistance.

Postconsumer fiber: Finished paper products that have been sold in commerce and have served their original purpose. As contained in the Resource Conservation and Recovery Act (RCRA), postconsumer material is "paper, paperboard and fibrous wastes from retail stores, office buildings, homes and so forth after they have passed through their end-usage as a consumer item, including used corrugated boxes, old newspapers, old magazines, mixed waste paper, tabulating cards and used cordage; and all paper, paperboard and fibrous wastes that enter and are collected from municipal solid waste".

Postpress operations: Supplementary operations to printing such as binding, finishing and distribution. The demands of finishing and postpress operations include folding, die-cutting, cutting, trimming, scoring, stitching, gluing and perforating.

Precommercial thinning: Stand-tending method, performed relatively early in the rotation, in which a stand is thinned by cutting down poor-quality trees and unwanted species (usually left in the forest). Precommercial thinning is done to reduce competition among trees for soil moisture, nutrients, light and space.

Preconsumer material: Defined by the U.S. Environmental Protection Agency as "materials generated during any step of production of a product, and that have been recovered from or otherwise diverted from the solid waste stream for the purpose of recycling, but does not include those scrap materials, virgin content of a material or by-products generated from, and commonly used within, an original manufacturing process." For paper recycling, includes trim from converting envelopes, paper plates and cups, boxes and cartons and printing runs , and over-issue publications and forms.

Prescribed burning: Managed application of low-intensity fire in a carefully prescribed area. Prescribed burning is done to control hardwoods and other brush in managed pine forests, including plantations.

Press: Sets of rolls through which the paper web passes during manufacture. This process occurs either to remove water from the web in the wet press; to smooth and level the sheet's surface in the smoothing press; or to apply surface treatments to the sheet in the size press.

Pressure sensitive adhesives: Adhesives that are activated by applying pressure; usually used in the manufacture of labels and tapes. According to deinking experts, the most difficult contaminants to remove during deinking are the polymeric adhesives used as pressure sensitive adhesives and hot-melt glues.

Pressure sensitive labels: "Peel and stick" labels.

Print quality: Paper properties that determine the quality of appearance of the sheet after printing, as judged by contrast, resolution of the printed image, type and reproduction of halftones.

Print resolution: The appearance of color, halftones, line art and type on the sheet.

Printability: A paper's ink receptivity, uniformity, smoothness, compressibility and opacity.

Printing and writing papers: Broad category is defined by the American Forest & Paper Association that includes coated and uncoated freesheet and coated and uncoated groundwood grades; it excludes newsprint.

psi: Pounds pressure per square inch.

Publication papers: Paper grades used in magazines, books, catalogs, direct mail, annual reports, brochures, advertising pieces and other publication and commercial printing products.

Pulp: Cellulose fiber material, produced by chemical or mechanical means, from which paper and paperboard are manufactured. Sources of cellulose fiber include wood, cotton, straw, jute, bagasse, bamboo, hemp and reeds.

Pulpwood: Roundwood products , whole-tree chips, or wood residues that are used for the production of wood pulp.

Purchased energy consumption: Amount of purchased electricity and fossil fuels that mills use to run the equipment and to generate process steam. Cogeneration and more efficient combustion of lignin and other wood waste decreases the purchased energy consumption of the mill.

Rag paper: Paper made from cotton cuttings and linters; usually referred to as cotton-fiber paper.

Reactivity: Propensity of a sheet to gain and lose moisture when subjected to heat and/or changes in humidity.

Ream: 500 sheets of printing paper.

Recovered paper : Paper collected for the purposes of recycling.

Recycling: The process by which materials that would otherwise be destined for disposal are used to manufacture products. In basic terms, successful recycling requires that four things happen in sequence: (1) collection of recyclable materials; (2) intermediate processing to remove contaminants, sort and compact materials for shipment; (3) manufacturing of new products; and, (4) the purchase of products containing recovered materials by business and individual consumers.

Recycled-content paper: Paper that contains come recycled fibers.

Reel: Roll onto which paper is wound at the end of the paper machine.

Refiner mechanical pulp (RMP): Mechanical pulp made using a single-disk or double-disk refiner.

Regeneration: Establishment and early development of new tree seedlings. In unmanaged forests, regeneration takes place on a variety of scales -- from individual trees to large areas of forest leveled by large-scale natural disturbance, such as wildfire. In managed forests, regeneration may be natural or "artificial" (performed through planting), and may occur at the level of an individual tree or small group of trees (following selection harvests in uneven-aged silviculture) or at the level of a stand (following clearcutting or other harvesting methods in even-aged silviculture).

Reprographic paper: Reprographic paper is multi-purpose paper designed for use in copy machines, laser printers, ink-jet printers and plain paper faxes. It is often referred to as dual purpose paper.

Residues: Bark and woody materials that are generated in primary wood-using mills when roundwood products are converted to other products. Examples are slabs, edgings, trimmings, miscuts, sawdust, shavings, veneer cores and clippings and pulp screenings; includes mill residues from bark and wood (both coarse and fine material), but excludes logging residues, which are included in roundwood.

Resource Conservation Recovery Act (RCRA): Federal hazardous and solid waste statute enacted in 1976 and amended several times, most significantly in the Hazardous and Solid Waste Amendments of 1984. Codified as Title 42 of the United States Code, Sections 6901 - 6987.

Rigidity: Stiffness; resistance to bending.

Riparian zone: See streamside management zone.

Rotation: In even-aged silviculture, the period of time between harvests. (Related terms: rotation age, referring to the age at which a stand is harvested, and rotation length, the length in years of the rotation.) Where production of solid wood or fiber is the management objective, the rotation age is generally timed to maximize the net economic return from the stand, allowing for considerations such as mill supply and demand. Rotation ages for pulpwood management are significantly shorter than for sawtimber (although pulpwood may also be harvested from forests managed on sawtimber rotations, in the form of logs too small or otherwise unsuitable for use as sawtimber). Rotation lengths vary depending on tree species, desired product, site quality and region.

Roundwood products: Logs, bolts and other round timber generated from harvesting trees for industrial or consumer use. In this volume, which follows the conventions of the USDA Forest Service and other federal agencies, roundwood includes so-called logging residues, which are wood chips made from wood that would otherwise be left on-site.

Runnability: Paper properties that affect the ability of the paper to run in office equipment and printing presses.

Sawtimber: Classification of timber inventory that is composed of sawlog-sized trees of commercial species. Sawlogs are logs meeting minimum standards of diameter, length and defect; they include logs at least 8 feet long that are sound and straight, and with a minimum diameter inside the bark of 6" for softwoods and 8" for hardwoods; other combinations of size and defect may be specified by regional standards.

SBS: Solid bleached sulfate paperboard

Scoring: Creasing by mechanical means to facilitate folding and guard against cracking of the paper or board.

Secondary fiber: Recovered paper.

Secondary treatment: Systems use microorganisms to convert the dissolved organic waste in the effluent into a more harmless form. Although primarily designed to remove BOD, secondary treatment also reduces the loading of COD and AOX.

Seconds: Paper that is damaged or has imperfections.

Sedimentation: Deposition of eroded soil into streams or bodies of water. Depending on stream flow and other site conditions, deposited sediment can settle on the stream floor, burying gravels in the streambed and degrading spawning habitat for fish. Elevated sediment concentrations in water can also harm filter-feeding organisms and may interfere with the functioning of the gills of some organisms.

Seed-tree method: Even-aged harvesting/regeneration method in which all of the merchantable timber in a stand is removed in one cutting, except for a limited number of seed trees left singly or in small groups as a seed source to facilitate natural regeneration. These trees typically are harvested after the stand has successfully regenerated.

Selection method: Harvesting/regeneration method used in uneven-aged silviculture in which mature trees are removed, individually (single-tree selection) or in small groups (group selection), from a given tract of forestland over regular intervals of time.

Semi-chemical: Pulp made by a combination of mechanical and chemical processes; typically used to make corrugating medium.

Shade-intolerant species: Tree species (or, more broadly, plant species) that are generally outcompeted in shaded conditions but grow vigorously in full sunlight. Many commercially valuable species, such as loblolly pine and Douglas fir, are shade-intolerant. Because of their preference for light, shade-intolerant species are usually managed using even-aged systems.

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

Sheet: Term applied to a single sheet, a paper grade or a description of the paper; i.e., coated, uncoated, or offset.

Sheeting: Process of cutting a roll of paper or board into sheets.

Shelterwood method: Removal of the mature timber from a stand in a series of cuttings (usually two) that extend over a relatively short portion of the rotation, in order to encourage the establishment of essentially even-aged reproduction under the shelter of a partial canopy. In irregular shelterwood, the period between the first and second cutting is extended to allow the development of a two-aged stand.

Shrinkage: Decrease in dimensions of a paper sheet; weight loss between amount of pulp used and paper produced.

Silviculture: The art and science of establishing, tending, protecting and harvesting a stand of trees.

Single-tree selection: Method of harvesting in which individual merchantable trees are removed periodically. Natural regeneration is typically relied on to fill in the resulting gaps.

Site preparation: Silvicultural activity to remove unwanted vegetation and other material, and to cultivate or prepare the soil for regeneration.

Size press: Press section of the paper machine, near the end, where sizing agents are added.

Sizing: Process that enables paper to resist penetration by fluids. Sizing can also provide better surface properties and improve certain physical properties of a sheet. The papermaker generally applies either surface or internal sizing, which can be applied as sole treatments or in combination

Skid trail: Temporary, non-structural pathway over forest soil used to drag felled trees or logs to the landing.

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

Slash: See logging debris.

Slice: Device that controls the flow of pulp from the headbox of a fourdrinier paper machine.

Slurry: Watery suspension of fibers or pigment used in papermaking or coating, respectively.

Smoothness: May be measured by the degree of resistance that the paper provides to air moving across its surface. Smoothness influences print quality, ink holdout and transport of paper through machine. The degree of smoothness of an uncoated grade of paper is determined by fiber species, fiber length and finishing processes such as surface sizing and calendering.

Snags: Dead but still standing trees. Snags are important habitat for many species of wildlife: an abundance of invertebrates; birds that construct or nest in cavities and/or feed on the invertebrates; and small mammals that live in the cavities.

Sodium hypochlorite: Bleaching chemical produced by mixing sodium hydroxide and elemental chlorine. Mills are eliminating this chemical from bleaching processes because it produces large quantities of chloroform.

Softwood: Coniferous usually evergreen tree that has needles or scale-like leaves; e.g., pine, Douglas fir and spruce.

Solid board: Paperboard made of only one type of furnish.

Sorted office paper: Paper typically found in offices; may contain a small percentage of groundwood papers such as computer printout and fax paper, but is free of unbleached fiber such as corrugated boxes.

Species diversity: Measure of the abundance and relative frequency of species in a specified area. Species diversity is often used with respect to animal or plant populations in a single stand, but can also be thought of on regional and global scales. For the purposes of biodiversity conservation, spatial scales of species diversity are hierarchical: global diversity is a higher conservation priority than regional diversity, and both are more important than local or stand-level diversity.

Stand: Contiguous group of trees sufficiently uniform in species composition, arrangement of age classes and condition to be a homogenous and distinguishable unit; also the area defined by the extent of those trees.

Starch: Sizing agent usually made from corn and potatoes; improves rigidity and finish by causing fibers to lie flat.

Stem-exclusion stage : The second stage of stand development in a forest, in which the forest canopy closes and the arrival (or recruitment) of new seedlings halts. Because a closed canopy limits the amount of light reaching the forest floor, understory growth is limited, stand vegetation is simpler and species diversity tends to be lower than in other stages.

Stickies: Particles of plastic, adhesives or naturally tacky materials (e.g., pitch from pine trees). embedded in the paper sheet or attached to the forming machine; caused by non-soluble residual particles of hot-melt glues, adhesive labels and other contaminants present in secondary fiber.

Stiffness: Ability of paper to resist deformation under stress and to resist bending stress. It affects how well the paper performs in transport through press and office equipment and during converting. The properties of stiffness are determined by the basis weight and caliper of the paper, the type and quantity of fiber and filler used in the paper, and the degree of fiber bonding.

Stock: (1) Paper or board that is in inventory. (2) Paper or board used in the printing or converting process. (3) Fibrous mixture that is made into paper; also called furnish. (4) Wastepaper.

Stone groundwood pulping (SGW): Processing of press logs against a grindstone while a stream of water wets the stone and removes the pulp. This process has the highest yield 93 - 96% of all pulping processes, but it also produces the weakest pulp.

Streamside management zone (SMZ): May also be called buffer strips or riparian management areas. Zone of forest along a forest stream where management practices that might affect water quality, fish or other aquatic resources are modified. Properly designed SMZs effectively filter and absorb sediments, maintain shade, protect aquatic and terrestrial riparian habitats, protect channels and str