copyright and disclaimer information

Technical terms and definitions

Like any profession, forestry has its own set of terms that are not commonly used in the English language. I have quite a few listed here, but not all of them.  I will try to include all terms I used on this site to improve clarity.

Advanced Regeneration: Healthy saplings 6’ or taller that are present in an understory of a forest.

Age class: A distinct aggregation of trees originating from a single environmental disturbance.

Basal area (B.A.): The area in square feet of the cross-section of tree trunks at 4.5’ up from the base of the tree.  This is often used as a measurement of relative density and is used in area/acre terms.  If I were to say 90 square feet basal area of red oak in a stand, that means that if you cut the trees at 4.5’ high, and calculated the surface area of each of the stumps in one acre of the stand and added them all together it would equal 90 square feet of surface area.  Keep in mind though, that this measurement is extremely variable within a stand. Usually, foresters measure density with an angle device, and often talk about B.A. in 10s of square feet; 60,70,80, etc.  It is not a very precise measurement, but works well for the management of forests.

Board foot: A measurement unit of lumber equal to 12” x 12” x 1” before the lumber is planed or dried. In volume measurements, there are three common rules that calculate the amount of board feet in a tree or log; Doyle, International 1/4”, and Scribner. The International 1/4” rule is the closest rule to what is actually produced, because it takes log taper into account. Doyle guarantees overrun on smaller logs, meaning small logs will have more actually produced wood in them then the scaled amount.  Scribner will generally produce overrun on 16’ logs larger than 28” diameter on the small end and under-run on smaller logs.

Canopy: The area(s) where the crowns of similar sized  trees come together and form a horizontal layer of vegetation within the forest.  All forests have one canopy, most have more than one.

Clear-cut: A timber harvest method that describes harvesting all the merchantable trees within a stand.

Co-dominant tree:  Trees with crowns forming the top line of the highest canopy level within a forest.  These trees receive most light from the top, but the light is blocked on the sides from other Co-dominant trees or dominant trees, the latter of which shade some of the light from above.

Conservationist: A person who believes in using resources conservatively.

Coppice: Regeneration through the means of vigorous stump sprouting from the root system.

Cord: 128 cubic feet of  wood (a stack 4’ x 4’ x 8’ which contains air in between the pieces of wood), roughly 79 actual cubic feet of wood, which is approximately equivalent to 500 board feet of wood.

Crown: The upper branches and main foliage of a tree.

Cull: An unmerchantable tree.

D.B.H.: Diameter at breast height. Breast height is defined as 4.5’ (54”) up from the high side of the base of the tree.

Dominant trees:  The tallest trees in the forest. These are trees which have crowns that are higher than the top of the highest canopy of the forest.

Epicormic Branching: Branches that protrude directly out of the main stem of a deciduous forest tree instead of at the top of the crown. Resulting from many environmental disturbances, epicormic stems can decrease timber value because they produce knots in the wood that otherwise wouldn’t be there.

Environmentalist: A person who places high values on the environment.

Forester: A person who practices forestry.

Forestry: The science based art of growing and caring for forests.

High-Grading: Also known as liquidation harvesting. Any number of methods of timber harvesting that harvest the best -formed timber trees and leave undesirable trees. This is a seriously detrimental action to a forest, as it negatively impacts the future structure of the forest.  It also loses the landowner money when the value of the future harvests is taken into consideration.

Intermediate trees: The trees that have crowns extending into the lower part of the highest canopy of the forest, or trees that make up a lower mid-story canopy below the highest canopy of the forest.

Natural regeneration: A stand that regenerates without the assistance of human intervention, either by seeding in or by coppice growth.

Pre-commercial thinning: A thinning that happens before the trees are at the value level where they can make the owner a net profit from the revenue of the timber sale.

Preservationist: A person who believes in preserving (not using) resources.

Release operation: A treatment designed to free otherwise suppressed trees from competing vegetation.

Salvage operation: A treatment that removes the dead or damaged trees that is used to recover the financial value that would otherwise be lost to decomposition or fire.

Seed tree cut: A harvesting technique where every tree is harvested except for the seed trees, which are typically the trees that have characteristics of that which is desired in the future forest. Regeneration is achieved through the micro environments that are created during the processes of harvesting operations.  Seeds are delivered to those micro environments by wind from the residual trees.  This method works extremely well with a species that requires relatively high amounts of sunlight and exposed mineral soil to seed in properly.

Selection thinning:  The removal of trees with specific attributes. High-grading is often disguised as “select-cut”.  Sometimes this involves removing dominant trees from the smaller-sized trees (thinning from above), or removing some of the co-dominants and intermediate trees from the dominant trees (thinning from below).  Single-tree selection is the process of which each tree is removed separately from the forest for a certain purpose. If properly done, the diseased or poorly formed trees that are competing for sunlight with more healthy trees will be chosen for removal, enhancing the overall value of the forest after the harvest.

Shelterwood harvest: The method of regenerating trees underneath the canopy of older trees, which creates a two-aged stand.  The environment for which the new stand starts to grow is partially shaded by the older stand, which allows certain species that thrive in a moderate amount of sunlight to flourish.

Silviculture:  The science-based art of controlling the establishment, growth, health, and quality of forests and woodlands. It deals with the manipulation of vegetation to meet various objectives established for a certain forest.

Site Class: A classification of site quality, usually expressed in terms of ranges of dominant tree heights at given ages.

Site Index: A measurement of how productive a forest site is.  It is the average height of a dominant or co-dominant tree of a specific species at a specific age (50 years for most species, 100 for some).  Theoretically used only on an even-aged forest, this measurement is commonly taken on all forests, and is a very important measurement for the consideration of the management regime to be used.

Timber Stand improvement:  Thinnings, prunings, pest management efforts, and other silvicultural operations done to improve the overall health of a forest.

Volume: A measure of wood in the forest or in the tree.  Usually represented in product quantities; board feet, cubic foot, cords, etc.  Often it is measured by the acre in the case of a stand volume; 10,000 board feet to the acre Doyle rule, etc.

Top of page