A Forestry, Forest Practices, Silviculture Glossary for Beginning Foresters

If you're new to forestry and forest management, or just beginning to develop ideas for starting a stewardship plan for your land, here is a glossary of basic forestry and silviculture terms.

Here are a list of forestry and silviculture terms we found the most important in our in-depth study of forest stewardship. When we started managing our forest and timberland a few years ago, we were novices. We invested the time to meet with other forest owners, schedule visits with certified foresters, and attend forestry seminars and workshops both in person and online. Hope this list of terms helps you. We provide a list of valuable resources in our The Silvicultural Practices at Hansen Woodland Farm.

Forestry, Forest Practices, Silviculture Glossary

Abiotic Forest Diseases: Damage to trees (and other plants) caused by non-living agent, such as environmental extremes, soil issues, mechanical damage.

Acre: Area of land containing 4,840 square yards -- or 43,560 square feet. (in the forest, think of a square section of approximately 70 yards -- or 209 feet.) In forestry operations, an acre is 10 square chains.

Ponderosa Pine Annual Rings Annual Ring: Bands within tree trunk that mark progression and age of tree. Rings actually have two components (seen as lighter and darker), early wood and late wood growth in the cambium. Wider gaps between rings show more favorable growing conditions. Tight rings are indicators of years when the tree was stressed, suppressed.

Aspect: An important topographic element in understanding tree stand development, and refers to direction that a stand faces. Aspect is an important concept because it largely controls the amount of sunlight that the trees in the stand receive.

Biotic Forest Diseases: Damage to trees (and others plants) due to living organisms, such as bacteria, viruses, fungi.

Bucking: Logging term for cutting fallen tree into logs for transport.

Chain: Measure of distance commonly used in forest operations. A chain is equal to 66 feet.

Cambium: A key element of a tree, located just inside the bark and phloem layers, which moves outward as tree grows in diameter -- forming new cells outside the old ones.

Canopy: Uppermost layer of forest stand, formed by the crowns of dominant trees.

Co-Dominant Trees: Trees that form the general level of canopy within a tree stand.

Cost-Share Programs: Assistance programs from state and federal agencies that help forest owners with financial and technical assistance in promoting forest health and improvements. In a typical cost-share, the owner and the governmental agency share the cost of the assistance.

Crown: the branches and foliage of a tree.

Crown Class: A method of classifying trees within a stand, starting with wolf trees, dominant trees, co-dominant trees, intermediate trees, and suppressed trees.

Cruise: survey of forestland to determine timber quantity for logging.

DBH: A method for measuring tree size; stands for (tree) diameter at breast height. For uniform measuring of tree diameters, measure all trees at 4.5 feet from the ground.

Disturbance: Natural (windstorm, flood, insect infestation) or human-caused (fire) event that alters structure and composition of forest. Primary disturbance is destruction down to the dirt; secondary disturbance results in limited damage.

Dominant Trees: The tallest trees in a stand, with crowns growing above the general level of the canopy.

Energy Priorities of Pine Trees: There are five levels of energy priorities for conifers:
  1. Stay alive when resources are limited
  2. Support the growth of fine roots and foliage
  3. Cone production
  4. Growth upward; root growth
  5. Diameter growth

Felling: Cutting down trees.

Forest Health: Good forest health is about creating a forest that is resilient to change and biologically diverse -- while also able to provide sustained habitat for vegetation, fish, wildlife, and people.

Forest Management Objectives: Guiding principles about what is important to the landowner.

Forest Management: Overall administration of forestland, including use of economic, legal, scientific, and social principles in managing a forest. Usually involves development of a forest management or forest stewardship plan.

Forest Practices: Laws and rules designed to protect public resources (such as water and wildlife) from poor forest practices. All private landowners must follow the forest practices of their state.

Forest Stewardship: Development of sound forest management principles (practical wisdom) for the short- and long-term health and development of forestland -- and covering issues such as tree health, fish and wildlife habitats, clean water, and recreational uses.

Girdling: A method (though not preferred) for creating a snag in which forester cuts a 4-inch belt of inner and outer bark, stopping flow of nutrients in the phloem, killing the tree. Only do this method far from structures, roads, and trails.

Hardwood Trees: Typically are deciduous trees. Known as angiosperms because they produce seeds with some sort of covering, such as a fruit (cherry) or shell (oak's acorn).

Intermediate Trees: Trees within a stand that have been somewhat suppressed by dominant and co-dominant trees surrounding them, thus with crowns that do not reach the level of the canopy.

Ponderosa Pine Leader Intolerant Trees: Trees that need light, sun -- that are shade intolerant.

Landing: Location where fallen logs are piled in preparation for hauling to mill.

Leader: The very top, vertical stem (terminal shoot) of a tree.

MBF: Thousand board feet. For example, in Washington state, private landowners can cut up to 5 MBF (about the equivalent of one log truck) for personal consumption without a forest practice permit.

Mixed-Species Stand: Forest stand that includes more than one species of tree. (Compare to Pure stand.)

Multistoried Stand: Tree stands that contain trees of different heights.

Old Growth Forest: An untouched stand consisting of older trees, typically more than 100 to 150 years old, (and older) and home to a diverse ecosystem.

Overstocked: A forest stand that contains too many trees relative to the resources available.

Overstory: Portion of the trees in a stand forming the upper crown cover.

Phloem: Located between the outer bark and the cambium, this element of a tree that carries nutrients (particularly sucrose) made from photosynthesis to all parts of the tree. (From the Greek word, phloos, meaning bark.)

Pitch: Resin occurring in the trunk of certain conifers, including the Ponderosa Pine, and used to protect the tree against damage... including from invasive species, such as bark beetles.

Pre-Commercial Thinning: Cutting number of trees in a young stand so that the remaining trees will have more room to grow to marketable size. Trees cut in a pre-commercial thinning have no commercial value -- and are typically chipped, burned, or used in some other non-commercial way. See also, Thinning.

Pruning: Typically done after thinning a stand -- removing lower limbs of remaining trees; pruning is done for reducing knots (and increasing board value), increasing tree health, and reducing fire ladders. Prune in fall or winter, not during spring growth.

Pure Stand: Forest stand that contains only one species of trees. (Compare to Mixed-Species Stand.)

Riparian: Anything dealing with the banks of a river, stream, or lake.

Sapling: A small tree, usually between 1 to 3 inches in diameter, and between 15 to 30 feet in height.

Seedling: A young tree, usually less than inch in diameter and no more than 3 feet in height -- and grown from a seed.

Silviculture: The art, science, and practice of establishing, tending, and reproducing healthy and high-quality forest stands with desired characteristics from owner's objectives -- based on knowledge of species characteristics and environmental requirements. Forest culture.

Silviculture Prescriptions: Implementation of silviculture procedures to produce desired outcomes while controlling disturbances in forest stands. Common prescriptions include thinning, pruning, prescribed fire, and regeneration cutting.

Site Index: Approximation of Site Quality, based on comparison of dominant tree height in stand to expected tree height (based on a site index table based on tree species and region).

Site Quality: Refers to the productive capacity of a forest stand -- a useful tool for predicting potential growth. It is affected by factors such as soil depth, soil texture and composition, slope, elevation, and aspect.

Ponderosa Pine Snag Skidding: Pulling downed trees -- logs -- with equipment or horses from harvest area to landing area.

Slash: All unusable trees materials left after thinning, pruning, and logging operations -- including branches, tree tops, bark, and stumps. Slash is typically left on forest floor, burned, or chipped -- depending on quantity and objectives of landowner.

Snag: A dead or dying standing tree, occurring naturally (disease, fire, drought, root rot) or through intervention (topping, girdling). Sometimes referred to as wildlife trees because birds and small mammals use snags for nesting, foraging, roosting. Best snag trees are conifers.

Softwood Trees: Typically are evergreen trees. Known as gymnosperms because they produce seeds that scatter to a wide area, blown by the wind.

Soil: Key to forest health, soil contains four main ingredients: mineral particles, organic matter, water, and air.

Soil Texture: Refers to the amount/proportions of soil particles -- sand, silt, and clay. Fine soils contain a high concentration of silt and clay. A soil composed of roughly equal amounts of the three particles is referred to as loam.

Stand: A recognizable unit of forestland, typically organized by tree species, tree age, geographic elements. Stands are most basic management units of a forest, and landowners divide forestlands into stands so they can develop specific forest practices for each unique unit.

Stand Density: An estimate of the quantity of trees within a unit of area, typically a stand -- and expressed as number of trees per acre.

Stand Structure: Defines the basic elements of a tree stand, from simple (all the same species, age) to complex (diverse species, ages).

Stumpage: Refers to commercial value of trees standing in a forest. Stumpage prices -- which depend partly on tree species, log quality and size, market demand, and logging costs -- may be offered in reference to board foot volume ($100 per m.b.f.) , weight ($7 per ton), or truck loads ($40 per load).

Sunscald: Injury to a tree's bark and cambium caused by an increased exposure to the sun, typically as a result of thinning.

Suppressed Trees: The weakest trees within a tree stand due to growth suppression from surrounding dominant trees, with crowns far below the canopy of the stand, often with other growth deformities as well.

Thinning: Forestry practice of removing smaller, damaged, and inferior trees in a tree stand to increase the health, productivity, and value of remaining trees (by reallocating key, limited resources). Thinning can be done consistently across a stand, or using variable intensity levels. [Learn more about thinning here.]

Thinning from Above: Commercial thinning strategy in which the best, dominant trees are thinned from a stand, leaving smaller, understory trees for future growth as canopy is cleared. Typically not favored, as there are too many negatives associated with this method (though there is bigger cash value in larger trees).

Thinning from Below: Commercial thinning strategy in which smaller understory trees, as well as surplus larger (dominant, co-dominant) trees, are harvested, leaving larger, overstory trees for future growth.

Hansen Woodland Tree Farm ATFS Thinning Intensity: An important forest management decision regarding thinning practices. Thinning done too lightly means having to come back and do a second and/or third thinning in future years; thinning too heavily can leave too few trees and even cause the loss of additional trees from excess wind and sun exposure (sunscald).

Thinning Strategies for Commercial Thinning: An intermediate step taken by forest landowners designed to increase forest health and commercial viability of remaining trees while providing a modest income from logging. Two strategies are Thinning from Below and Thinning from Above.

Timber Harvest Plan (THP): A document that details planned logging operations for a specific forest harvest -- and the steps that will be taken to minimize environmental impacts (roads, skidding damage, water issue) of these operations.

Tree Farm: Privately owned forestland in which developing and growing healthy, productive forest and producing valuable timber for commercial use is major management goal. Learn more the American Tree Farm System.

Tree Resources: All trees within a forest are competing for three key limited resources: light, water, and nutrients.

Tree Topping: A poor forest management technique, but an effective one for creating a snag tree.

Understory: Elements of trees, as well as other vegetation, below the canopy in a forest stand.

Variable Density Thinning: Process of thinning tree stand in which, in order to create diversity within the stand, the forester thins lightly in some areas, while thinning more heavily in others.

Wildlife Habitat: Any parts of the forest that are used by wildlife for nesting. Forest owners can increase wildlife habitats through use of snags and small slash piles.

Wolf Tree growing in forest Windthrow: Trees (often weak or defective) uprooted or topped off by wind.

Wolf Tree: Old, dominant tree that has no direct competition from other trees (or did for most of its life), leading to massively thick, wide-spreading branches. Originally seen as bad (hence the wolf name), but foresters now realize that these trees are favored by wildlife.

Yarding: Moving cut logs from where they were felled to landing area.


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