Glossary of terms

Some commonly used terms in the forestry industry

Basal area - Basal area is the cross-sectional area of trees in a stand at breast height (1.3m or 4.5 ft above ground)

Beating up - is the operation carried out to replace any seedlings that may have died (or are struggling) immediately after planting.

Biomass - Material that is derived from living, or recently living, biological organisms.

Broadleaves - Trees that do not have needles or cones, such as oak, birch and beech. A few, such as alder, have cone-like structures for their seeds which are not true cones.

Clearfell areas - Sites where all trees have been felled at once. In non-clearfell areas, only some trees are felled at any one time.

Conifers - Trees with needles and cones, such as spruce, pine and larch.

Diameter at Breast Height (DBH) -  measured at 1.3m above the ground, DBH is a standard method of expressing the diameter of the trunk of an individual standing tree

Establishment - The first five to ten years or formative period that ends once young trees are of sufficient size that, given adequate protection, they are likely to survive at the required stocking.

Forest - In the United Kingdom, there is no formal definition of “forest”; the term is often used for large woodland areas (especially conifers) or for old Royal hunting preserves such as the New Forest or the Forest of Dean.

GIS - Geographic Information System, software that combines map data with features to create, manage and analyse location information

Growing stock & standing volume - The volume of timber in living trees. 

Hectare (ha) - Unit of area defined as 10,000 square metres (100 m by 100 m), approximately equivalent to 2.47 acres.

Increment - The growth rate of standing trees.

Natural regeneration - The regeneration of existing woodland by natural means, i.e. without sowing or planting.

NDVI - normalized difference vegetation index is a widely-used metric for quantifying the health and density of vegetation using sensor data.

New planting - Establishing woodland on ground that was not woodland in the recent past.

Overbark - The volume of wood including the bark. Can be either standing volume or felled volume.

Phytophthora ramorum - Fungus-like pathogen of plants that causes extensive damage and mortality to trees (including Japanese larch) and other plants.

Restocking - The replacement of trees on areas of woodland that have been felled; this can be done either through replanting or natural regeneration.

Roadside sales - Sales of timber after harvesting. The owner is responsible for getting the trees felled and extracting them to the side of the road, ready to take away.

Roundwood - Trunk or branch wood, generally with a top diameter of 7 cm or more. Can be in the form of logs (14 cm top diameter or more) or small roundwood (7 to 14 cm).

Sawlogs - Material of at least 14 cm top diameter that is destined to be sawn into planks or boards.

Scrub - Area of poorly formed trees or bushes unsuitable for conversion to timber.

Silviculture - The care and cultivation of forest trees.

Stand - A relatively uniform collection of trees (from either planting or natural regeneration) composed, for example, of a single species or a single age class.

Standing sales - Sales of timber while the trees are still standing. The buyer is responsible for getting the trees felled and removed from the site.

Standing volume - Measurement of quantity before trees are felled. Usually expressed as cubic metres overbark standing.

Statutory Plant Health Notice (SPHN) - Statutory Plant Health Notices, requiring the felling of infected trees, are issued by the Forestry Commission/ Natural Resources Wales/ Forest Service to prevent the spread of pests and diseases. They are currently being issued to control the movement of material infected with Phytophthora ramorum.

Stocked area - Area stocked with living trees. This differs from the woodland area (see below) in that felled areas awaiting restocking and areas of integral open space are generally excluded from the stocked area.

Stratification - A sampling technique where the entire population is divided into groups, or strata, and a random sample is selected within each group. Stratified sampling is often used to ensure that sufficient numbers from each group are included in the overall sample, particularly where results are required for each group.

Timber height – the vertical distance from the base of the tree to the point on the main stem where the diameter is a minimum of 7cm. This is because a diameter of 7cm is the minimum size for a trunk to be saleable timber.

Thinning - A proportion of stems removed in order to give the best stems space and light to grow into a more valuable crop. This is usually carried out some time after canopy closure and may be repeated at intervals. It is a necessary operation in the production of quality timber. A temporary reduction in standing volume will result.

Top height - In an even-aged forestry plantation, the mean height of the 100 trees of largest diameter at breast height (dbh) per hectare. These are not necessarily the tallest trees.

Total height – the vertical distance from its base to the uppermost or highest point or tip. 

UAV - an unmanned aerial vehicle (an aircraft piloted by remote control or onboard computers).

Validated - The initial evaluation of a project or group against the requirements of the Woodland Carbon Code. Upon completion a project/ group will receive a ‘Validation Opinion Statement’. The project/ group will then be certified for a period of up to five years.

Verified - Verification is the evaluation of a Woodland Carbon Code project as it progresses to confirm the amount of CO2sequestered to date as well as that it continues to meet the requirements of the Code.

Woodland - Land under stands of trees with a canopy cover of at least 20% (25% in Northern Ireland), or having the potential to achieve this, including integral open space, and including felled areas that are awaiting restocking.

Woodland Carbon Code -  is the UK standard for afforestation projects for climate change mitigation. More information can be found at UK Woodland Carbon Code