​Forest terminology


Acre: A unit of land containing 43,560 square feet. If it is a square, it would have a side of 208 feet by 208 feet.

American Tree Farm

American Tree Farm System® (ATFS®): An internationally-recognized certification program endorsed by PEFC, run by the American Forest Foundation, that provides family and private forest owners with guidelines on forest sustainability and third-party certification. The ATFS mission is to "promote the growing of renewable forest resources on private lands while protecting environmental benefits and increasing public understanding of all benefits of productive forestry". 

Basal Area

Basal Area: Cross-sectional area of a tree, measured at DBH. Typically known as a measure of stand density, expressed in square feet/acre.


Best Management Practices (BMP's): BMP's are designed to protect water quality during forest harvests, and are developed to mimic and/or protect the natural functions of forests. It is a collection of techniques in all aspects of operations, such as road building, stream crossings, how to correctly install bridges and culverts, trails, water diversions, log landings, etc.


Biofuels: organic material such as wood, waste, and alcohol fuels, as well as gaseous and liquid fuels produced from these feedstocks when they are burned to produce energy.

Board Foot

Board Foot: Unit of measure, a 1" by 1' by 1' board. Used in scaling sawlogs and veneer.

Boreal Forest

Boreal Forest: a region in North America that consists of mostly coniferous forest land. Also called "taiga", this type is the coldest forest zone in the northern hemisphere and covers a 1,000 km wide band over the continent.

Buffer Zone

Buffer Zone: A transitional zone between two distinct habitats, a buffer zone can act to protect sensitive areas from degradation and may provide additional diversity within a landscape. Generally used along water bodies or around dwellings.


Chain: a Surveyor's unit of measure equaling 66 feet. Commonly used in deed descriptions.

Chain of Custody

Chain of Custody (CoC): This is the process by which certified forest products are verified to come from properly managed, sustainable sources. Organizations wishing to become CoC certified must meet the minimum requirements in product traceability, storage and handling, invoicing, and record keeping. An on-site audit by an accredited third-party verifier is necessary before an organization can become CoC certified.


Cord: A unit of measure for stacked wood encompassing 128 cubic feet of wood, bark and air space (4' by 4' by 8')

Crop Tree

Crop Tree: Those trees in a stand left after thinning and destined to form the "final" crop, usually the highest in quality and value of all the trees in a stand.


DBH: Diameter at breast height, measure 4.5 feet above the ground.

Den Tree

Den Tree: A tree with a cavity or cavities used by wildlife.

Dominant Tree

Dominant Tree: A tree which usually has a large healthy crown that is part of the overstory. This tree will dominate its immediate area. It receives full light from above and partly from the sides.


Edge: The place in the environment where two distinct habitats meet. And edge often provides resources needed by a variety of wildlife, like food and cover.

Epicormic Branchin

Epicormic Branching: Branches arising from buds in the bark along main stem, most commonly occurring in trees under crown stress.


Forest Stewardship Council® (FSC®): In terms of the FSC scheme, there are two types of certification. In order for land to achieve FSC endorsement, its forest management practices must meet the FSC's ten principles and other assorted criteria. For manufacturers of forest products, including paper manufacturers like Sappi, Chain of Custody (CoC) certification involves independent certification of the supply chain, which identifies and tracks the timber through all stages of the production process from source to end product. Our Cloquet, Somerset and Westbrook Mills are FSC (FSC-C014955) chain of custody certified. Sappi’s Matane Mill is FSC (FSC-C151943) chain of custody certified.

Forest type/stand

Forest type/stand: A group of trees, occupying a specific area and uniform in composition, species, age arrangement and condition, as to be distinguished from other adjoining forested areas.


Geographic Information Systems (GIS): Integrates hardware, software and data in order to manage, analyze, and display a variety of information.


Girdle: The removal or killing of a ring of bark around the tree stem so that the flow of nutrients from the crown to roots is blocked. The roots die and the whole tree is killed.

Greenhouse gases

Greenhouse gases (GHGs): The GHGs included in the Kyoto Protocol are carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulphur hexafluoride.

Intermediate Tree

Intermediate Tree: A tree shorter than a dominant stem but extends into the crown cover formed by dominant and co-dominant trees. They receive some direct sunlight from above but none from the sides.


Landing: A place where logs and pulp are assembled for loading and transportation to a mill. Other names include header, yard, and deck.

Liquidation Harves

Liquidation Harvesting: This is a Maine-specific legal term. The Maine legislature has defined this as "the purchase of timberland followed by a harvest that removes most or all commercial value in standing timber, without regard for long-term forest management principles, and the subsequent sale or attempted resale of the harvested land within 5 years."

Management Plan

Management Plan: A management plan is a document that contains the landowners goals and objectives, current physical descriptions of the property, harvest plans for the present and future, identifies cultural and environmental areas of interests, etc. A current management plan is required if you are enrolled into Tree Growth Tax Law (State of Maine) or under the American Tree Farm System®.


Mast: Any nut, seed, or fruit produced by woody plants and consumed by wildlife.


MBF: Thousand board feet of sawlogs; 2 cords = 1 MBF, approximately.

Overstory Removal

Overstory Removal (OSR): Is the last phase in a Shelterwood system, where the mature trees are completely removed and the younger stand takes over as the dominant canopy.


Overtopped/Suppressed: Trees with crowns entirely below the general level of the canopy (dominant and co-dominant trees), receiving no direct light either from above or from the sides.


Programme for the Endorsement of Forest Certification (PEFC): The world's largest forest certification system, the PEFC is focused on promoting sustainable forest management. Using multi-stakeholder processes, the organization develops forest management certification standards and schemes promoted by 49 national members in Europe and other inter-governmental processes for sustainable forestry management around the world. Our Cloquet, Somerset and Westbrook Mills are PEFC chain of custody certified (PEFC/29-31-10). Sappi’s Matane Mill is PEFC (PEFC/26-31-135) chain of custody certified.


Raptor: Predatory birds such as hawks and eagles.


Regeneration: Young forest trees produced naturally from seed of mature trees.

Renewable Energy

Renewable Energy: Energy generated from natural resources, such as sunlight, wind, water, wood, geothermal, etc, which are naturally replenished.

Residual Stand

Residual Stand: Those trees remaining uncut following a harvesting operation.

Riparian Area

Riparian Area: An area adjacent to a water body such as a stream or pond, also acts as the transitional zone between aquatic habitats and dry or upland habitats. Riparian areas are very important in the protection of water quality and have many values for wildlife.


Sapling: A small tree less than four inches at diameter at breast height (dbh), and over 4.5 feet tall. These are usually but not always young trees.


Sawlog: A portion of a tree that meets minimum standards of diameter, length, and defect for sawmills. Usually at least 8' long, sound and straight, and with minimum diameters specified by specific sawmills. Boards are sawn from sawlogs to be made into furniture, flooring and construction lumber, etc.


Scarification: The disturbance of the forest floor to expose areas of mineral soil. This is done to prepare a seedbed and encourage establishment of desired species of tree seedlings, i.e. white pine or northern hardwoods.

Seed Tree System

Seed Tree System: The removal of the mature stand in one entry, except for a few individuals which will act as the seed source to regenerate the forest floor.

Shelterwood System

Shelterwood System: Is when in a timber management, a new stand of trees is started in the environment before the older one is removed.

Site index

Site index: The height to which a tree species will grow in 50 years on a given site.


Slash: The tops, branches and non-merchantable parts of trees left on the forest floor after a harvesting job.


Snags: Dead standing trees, often with tops broken off; which serve as perches, lookouts, foraging, and home sites for wildlife. They are also considered extremely hazardous by OSHA.

Species Diversity

Species Diversity: Maintaining a number of wildlife and/or tree species; requires diversity of habitats.

Spring Pole

Spring Pole: Saplings or smaller trees that are bent over by a larger felled tree. They can be under extreme tension and are dangerous if not cut properly.


Stocking: The degree of occupancy of the growing space of land by trees, measured in stems/acre.


Sustainable Forestry Initiative® (SFI®): The SFI program promotes sustainable forestry practices through a comprehensive set of standards covering forest management, fiber sourcing and the manufacturing and sale of forest-based products.  SFI standards require maintaining forest productivity and health; implementation of best management practices to protect soil and water quality; measures to conserve and enhance biological diversity, wildlife habitat, species at risk and Forests with Exceptional Conservation Value; providing employee, contractor and harvesting professionals with training and education; supporting research; and broadening the practice of sustainable forestry through landowner outreach and community involvement. SFI’s Chain-of-Custody standard requires implementation of an accounting system that tracks forest fiber content through production and manufacturing to the end product. SFI-certified organizations undergo annual audits by third-party accredited certification bodies. Our Cloquet, Somerset and Westbrook Mills are SFI® chain of custody certified.


Sprouts: Regeneration of stems coming from the stump of a harvested tree. Trees that commonly do this are red maple and beech.

Stem Exclusion

Stem Exclusion: Where trees start to compete with each other for nutrients; vigorous stems survive and weaker ones die.


Stumpage: A term used to describe the value of standing timber.


Suckers: Regeneration of stems coming from the roots of a harvested tree. Trees that commonly do this are poplars.


Topography: The characteristic of the land determined by surface features; usually expressed as flat, rolling, gently rolling, or mountainous.

Tree Farm

Tree Farm: See American Tree Farm System®.

Tree Growth Tax La

Tree Growth Tax Law: This law, which is specific to the State of Maine, is designed to assist forest landowners in maintaining their parcels as productive forests by helping to reduce taxes per acre of land. To enroll, you must have at least 10 acres of land managed for forest products and a management plan.


TSI: Timber stand improvement. Pre-commercial or noncommercial thinning, weeding, and/or crop tree release.

Veneer Logs

Veneer Logs: Usually a very high quality product. Veneer is peeled or sliced for paneling, furniture, and other uses.

Vernal Pool

Vernal Pool: A seasonal water body that has no permanent inlet, no viable population of fish, provides breeding ground, and is habitat for endangered and rare animals. Vernal Pools can contain up to 4 'indicator' species, which gives a idea of how healthy and significant the pool is. The four species are wood frogs, blue spotted salamanders, yellow spotted salamanders, and fairy shrimp. Since Fall of 2007, significant vernal pools became protected under the Natural Resources Protection Act (NRPA). In order to be considered significant, a pool needs to meet certain criteria over an extended period of time.


Vigor: Ability of a tree to transform environmental resources into its own substances in large quantities and at a rapid pace.

Wildlife Habitat

Wildlife Habitat: Four basic components of habitat are food, water, cover, and space. Specific requirements for each of these components will vary with species, season of year, and the age and sex of the animal.

Wolf Trees

Wolf Trees: Usually large in size, limby, and poorly formed with little timber value. Same function as snags, except the tree is still alive and possibly producing mast.