Our last in the series of Forestry terms deals with measurement and if you are planning to cut timber, these are terms you will likely hear and want to be familiar with. The picture to the left is a prime example of a defect in a tree which can considerably alter its worth when cutting timber. For more information on timber measurement, view the Greenwood Project video on log scale sticks.
Acre – An area of land measuring 43,560 square feet or 10 (66-foot) surveyor’s chains by 1 (66-foot) chain.
Basal Area – The measurement taken, usually reported in square feet per acre, of the area of the cross sections of tree trunks at 4½ feet above the ground and inclusive of the bark. Basal area gives an idea of the stocking of trees in a stand.
Board Foot – The measurement unit for lumber equaling 1 inch thick and 12 inches square. This measurement is most often used for measuring saw timber.
Chain – The unit of length used by surveyors measuring 66 feet.
Chip-n-saw – The class size for mid-sized trees (larger than pulpwood, but smaller than sawtimber) that produce both chips and dimensional lumber.
Cord – The standard unit of measurement for a pile of stacked wood. A full cord stands 4 feet high by 4 feet wide and 8 feet long, a total of 128 cubic feet of space. For southern pine, there are approximately 90 cubic feet of solid wood per cord. This measurement is most often used for pulpwood.
Cubic Foot – A volume of wood equivalent to a solid cube measuring 12 x 12 x 12 inches.
Diameter breast height (DBH) – Measurement of the diameter of a tree stem, outside the bark, taken 4½ feet above the ground on the uphill side of the tree.
Defect – Characteristics of a tree that may decrease its value for lumber. These can include rot, scars, or crooked stems. In forest inventories, this is often expressed as a percentage of the total volume.
Dendrochronology – The history of a tree; can be determined by examining the growth rings from an extracted core, stump, or cross section of a tree.
Diameter tape – Usually used at breast height, this cloth or metal tape measures diameter by wrapping the side of the tape calibrated in units of pi around the circumference of the tree.
Diameter class – Classification of trees based on the diameter of the tree stem at breast height; may be used to classify into product types.
Diameter outside bark (DOB) – The measurement of the diameter of a tree stem, including the bark.
Face cord – Standard unit of measurement for stacked firewood standing 4 feet high and 8 feet long, with a piece length under 4 feet (usually about 16 inches).
Fixed area sampling – A method of inventorying a forested area using plots of a standard size. Plots are usually square or circular and are used to assess characteristics such as species, diameter, and height of vegetation on a site.
Flagging – The practice of placing flags in trees or vegetation distinguishing some kind of border (such as a property line) or identifying something in need of attention (such as a hazard).
Green weight – The weight of wood immediately after it has been cut, before drying.
Hypsometer – An instrument (looks similar to a yardstick) used to measure the height of tall structures, such as trees and buildings. In some cases, a hypsometer is also used to determine the number of 16-foot logs in a tree.
Increment borer – Used to determine the age of a tree, an increment borer includes an extractor tray within a long skinny tube. Once augured into the trunk, a sample of tree tissue is extracted and the rings are counted to determine age. For some species, additional years are added to the number of rings; for example, for loblolly pine 3 years are added, and for longleaf 7 years are added.
Legal description – Information contained in documents, such as deeds and tax records, that identifies the location of land; usually uses a grid system employed by the Public Land Survey System.
Live crown ratio (LCR) – The ratio of the length of the tree’s crown (upper portion of the tree consisting of healthy, green foliage) to its total above ground height. Often reported as percentage, LCR is an indicator of tree health.
Log grade – A classification of logs based on specifications, such as length, diameter, or pith location, as well as imperfections or defects, that indicate the quality or relative value of a log.
MBF – Abbreviation indicating 1,000 board feet. This measurement unit is often used in the trade of dimensional lumber.
Metes and Bounds – A system for describing property boundary lines using physical features of the land, directions, and distances; often found on tax records and deeds.
Point sampling – A method of inventorying a forested area based on tree size to determine basal area of a stand. Samples are taken using a prism or angle gauge to determine which trees will be counted in the inventory. Point sampling does not require direct measurement of tree diameter or plot area.
Poles – When referring to product classification, poles are generally trees ranging from 10 to 24 inches DBH, are at least 30 feet tall, and have a top diameter of 6 inches or greater. Additionally, they must be very straight and free of imperfections such as catfaces, forks, or fusiform rust. They generally have the highest value of any forest product and are considered a premium product.
Pulpwood – A smaller class size of trees that are usually chipped and made into paper products. Larger-diameter trees of lower quality may also be purchased by mills as pulpwood.
Saplings – Young trees, usually between 1 and 5 inches DBH and often have no merchantable value.
Sawlog – A log (usually at least 16 feet long) from which lumber can be sawn.
Sawtimber Trees – 10 inches DBH or greater and 24 feet or taller to a 6-inch top that are free of major defects such as branches, forks, or diseased stem and can yield dimensional lumber.
Site – (a) The physical location of a stand of trees; or (b) the environmental conditions within which trees grow.
Site class – A measure of the quality of a site and the land’s potential to produce trees.
Site index – A measure of the quality of a site and its productivity based on the average heights of the tallest (dominant and co-dominant) trees in a stand at a given base age (usually 25 or 50 years). Site index is specific to particular species, climates, and regions, and is used to prescribe silvicultural practices and project future tree growth.
Site quality – A measurement, based on standard indicators, of the land’s potential to grow trees. Usually refers to the productive potential of a particular species at a given time and location.
Timber cruise – A statistical sample of a forest area to determine the location, volume, and other characteristics of timber, usually in preparation for a harvest or to guide management decisions.
Ton – A measurement of gross weight, usually given for green (not yet dried) material. This measurement is often used to determine the amount of wood delivered to the mill.
Yield – The volume of standing trees on a site.
Wedge prism – A small, slightly angular piece of glass used when sampling variable radius points to determine whether a tree is to be included in an inventory.