Glossary of Forestry Terms - D - E

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Damaged timber timber that has been affected by injurious agents such as wind (as in the case of blowdown), fire, insects, or disease.
Danger tree a live or dead tree whose trunk, root system or branches have deteriorated or been damaged to such an extent as to be a potential danger to human safety.
DBH (diameter at breast height) the stem diameter of a tree measured at breast height, 1.3 metres above the ground.
Deactivation measures taken to stabilize roads and logging trails during periods of inactivity, including the control of drainage, the removal of sidecast where necessary, and the re-establishment of vegetation for permanent deactivation.
Debris initiation and transport hazard the relative risk of gully wall failure and/or debris movement in gully channels, as tempered by the stream runout distance.
Deciduous perennial plants which are normally leafless for some time during the year.
Declination (magnetic) the angle between true (geographic) north and magnetic north (direction of the compass needle). Declination varies from place to place and can be 'set' on a compass for a particular location.
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Deferred area an area specified in a higher level plan where timber harvesting or other forest development activities have been postponed for a period of time or that the district manager has determined should not be harvested or otherwise developed until a higher level plan for the area is completed.
Deficit forest a forest in which existing stands cannot provide enough harvest volume to maintain the harvest at the level of long run sustained yield until the stands created when existing stands are cut become available for harvest. See also Surplus forest.
Defoliator an agent that damages trees by destroying leaves or needles.
Deforestation clearing an area of forest on a non-temporary basis for another use. Clearcutting (even with stump removal), if shortly followed by reforestation for forestry purposes, is not deforesting.
Degradation the diminution of biological productivity or diversity.
Deleterious substance any substance that, if added to water, would degrade or alter the quality of the water so that it becomes deleterious to fish or fish habitat, or becomes unsuitable for human consumption or any other purpose for which it is legally licensed (such as irrigation and livestock watering).
Depletion an income tax allowance reflecting the purchase price paid for merchantable timber, usually on fee simple land. Also, a term used to refer to the process of harvesting your growing stock.
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Designated area an identifiable geographic unit of the forest land base that requires a specific combination of forest practices to adequately protect important resource values.
Designated official Commonly used to refer to a person designated by name or title to be a designated resources official, designated environment official, or designated forest official.
Designated wilderness see Wilderness area.
Desired future stand condition a description of the characteristics of the future stand.
Desired plant community a plant community that produces the kind, proportion, and amount of vegetation necessary for meeting or exceeding the land use plan or plan objectives established for an ecological site. The desired plant community must be consistent with the site's capability to produce the desired vegetation through management, land treatment, or a combination of the two.
Determination any act, omission, decision, procedure, levy, order or other determination made under provincial forestry acts.
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Detrimental soil disturbance changes caused by forest practices in the physical, chemical, or biological properties of the soil, including the organic forest floor and the mineral soil extending from the surface to the depth at which the unweathered parent material is encountered. Such changes may result in a loss of productive growing site, reduced site productivity, or adverse impacts on resource values.
Development the advancement of the management and use of natural resources to satisfy human needs and improve the quality of human life. For development to be sustainable it must take account of social and ecological factors, as well as economic ones, of the living and non-living resource base, and of the long-term and short-term advantages and disadvantages of alternative actions.
Development objectives the short-term (often 5-year) planning objectives for a specific management area.
Development plan a specific plan outlining harvesting, road construction, protection, and silviculture activities over the short-term (often 5 years) in accordance with the approved forest management plan.
Dewatering condition in stream channel when all the water flow occurs within the permeable streambed sediments, so no surface water is left; common in small streams with considerable accumulations of gravel.
Diameter limit the removal of trees from a stand, based on the criterion of diameter. Generally, trees of less than a predetermined diameter are left unharvested
Diameter tape a graduated tape based on the relationship of circumference to diameter which provides direct measure of tree diameter when stretched around the outside of the tree, usually at breast height. See DBH.
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DIB (diameter inside bark) the diameter of a tree or log excluding bark thickness.
Dibble a tool used to make holes in the ground for planting tree seedlings.
Difficult site forest sites with environmental conditions that are unfavorable for tree establishment and growth.
Direct seeding the application of tree seed to a denuded area to regenerate it with commercially valuable species.
Disc trencher a machine designed for mechanical site preparation. It provides continuous rows of planting spots rather than intermittent patches as provided by patch scarifiers. Consists of scarifying steel discs equipped with teeth.
Discretionary authority the power to make a decision where the choice of whether to make a decision is that of the decision maker.
Dispersed retention retaining individual trees scattered throughout a cutblock.
District manager the manager of a Forest Service district office, with responsibilities as outlined in a Provincial Forest Act.
Disturbance a discrete event, either natural or human-induced, that causes a change in the existing condition of an ecological system.
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DOB (diameter outside bark) the diameter of a tree or log including bark thickness.
Dominant trees with crowns extending above the general level of the canopy and receiving full light from above and partly from the side; taller than the average trees in the stand with crowns well developed.
Dot grid a transparent sheet of film (overlay) with systematically arranged dots, each dot representing a number of area units. Used to determine areas on maps, aerial photos, plans, etc.
Drag scarification a method of site preparation that disturbs the forest floor and prepares logged areas for regeneration. Often carried out by dragging chains or drums behind a skidder or tractor.
Drainage basin area of the earth's surface from which surface drainage all flows to a single outlet stream (a watershed in North America).
Drainage structures include metal and wooden culverts, open-faced culverts, bridges, and ditches.
Drainage system a system designed to control the flow of water within a road prism.
Drawdown the process of reducing allowable annual cuts to a sustainable level.
Duff the layer of partially and fully decomposed organic materials lying below the litter and immediately above the mineral soil. It corresponds to the fermentation (F) and humus (H) layers of the forest floor. When moss is present, the top of the duff is just below the green portion of the moss.
Dust palliatives chemicals or compounds applied to road surfaces to reduce dust created by traffic.
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Ecological balance a state of dynamic equilibrium within a community of organisms in which genetic, species and ecosystem diversity remain relatively stable, subject to gradual changes through natural succession.
Ecological classification an approach to categorizing and delineating, at different levels of resolution, areas of land and water having similar characteristic combinations of the physical environment (such as climate, geomorphic processes, geology, soil and hydrologic function), biological communities (plants, animals, microorganisms and potential natural communities) and the human dimension (such as social, economic, cultural and infrastructure).
Ecological health both the occurrence of certain attributes that are deemed to be present in a healthy, sustainable resource, and the absence of conditions that result from known stresses or problems affecting the resource.
Ecological integrity the quality of a natural unmanaged or managed ecosystem in which the natural ecological processes are sustained, with genetic, species and ecosystem diversity assured for the future.
Ecological reserve areas of Crown land which have the potential to satisfy one or more of the following criteria:
  • areas suitable for scientific research and educational purposes associated with studies in productivity and other aspects of the natural environment;
  • areas which are representative of natural ecosystems;
  • areas in which rare or endangered native plants or animals may be preserved in their natural habitat; and
  • areas that contain unique geological phenomena.
Ecological units areas of land with similar biological, geological, and climatic environments.
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Ecologically suitable species coniferous or deciduous tree species that are naturally adapted to a site's environmental conditions, including the variability in these conditions that may occur over time.
Economically operable forest stands for which log prices exceed harvesting costs, including profit and return to capital.
Ecoregion classification the ecoregion classification system is used to stratify terrestrial and marine ecosystem complexity into discrete geographical units at five different levels. The two highest levels, Ecodomains and Ecodivisions, are very broad. The three lowest levels, Ecoprovinces, Ecoregions and Ecosections, are progressively more detailed, narrow in scope and relate segments to one another. They describe areas of similar climate, physiography, oceanography, hydrology, vegetation and wildlife potential.
Ecosystem a functional unit consisting of all the living organisms (plants, animals, and microbes) in a given area, and all the non-living physical and chemical factors of their environment, linked together through nutrient cycling and energy flow. An ecosystem can be of any size - a log, pond, field, forest, or the earth's biosphere-but it always functions as a whole unit. Ecosystems are commonly described according to the major type of vegetation, for example, forest ecosystem, old-growth ecosystem, or range ecosystem.
Ecosystem integrity the soundness or wholeness of the processes and organisms composing the ecosystem.
Ecosystem management the use of an ecological approach to achieve productive resource management by blending social, physical, economic and biological needs and values to provide healthy ecosystems.
Ecosystem productivity the ability of an ecosystem to produce, grow or yield products - whether trees, shrubs or other organisms.
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Ecotone a transition area between two adjacent ecological communities usually exhibiting competition between organisms common to both.
Edatope refers to a specific combination of soil moisture regime and soil nutrient regime.
Edge the outer band of a patch that has an environment significantly different from the interior of the patch.
Edge/area ratio length of forest edge per cutblock area.
Edge effect habitat conditions (such as degree of humidity and exposure to light or wind) created at or near the more-or-less well-defined boundary between ecosystems, as, for example, between open areas and adjacent forest.
Element an identifiable component, process or condition of an ecosystem.
Endangered species See Threatened or endangered species.
Endemic species a species whose natural occurrence is confined to a certain region and whose distribution is relatively limited.
Entrainment mobilization, by flowing water, of sediment or organic debris from the bed or banks of a stream channel.
Entrenched a legislative requirement which previously may only have been required by contract or policy.
Environmental rehabilitation measures undertaken to remedy environmental damage done to the land.
Environmentally sensitive areas (ESAs) areas requiring special management attention to protect important scenic values, fish and wildlife resources, historical and cultural values, and other natural systems or processes. ESAs for forestry include potentially fragile, unstable soils that may deteriorate unacceptably after forest harvesting, and areas of high value to non-timber resources such as fisheries, wildlife, water, and recreation.
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Even-aged a forest stand or forest type in which relatively small (10-20 year) age differences exist between individual trees. Even-aged stands are often the result of fire, or a harvesting method such as clearcutting or the shelterwood method.
Even-aged silvicultural system a silvicultural system that is designed to regenerate and maintain an even-aged stand. Clearcutting, seed tree, and shelterwood are even-aged systems.
Even-aged stand a stand of trees consisting of one or two age classes. Even-aged stands are often the result of fire, or a harvesting method such as clearcutting or shelterwood.
Even flow in harvest scheduling, the requirement that the harvest level in each period be equal to the harvest level in the preceding period.
Evergreen never entirely without green foilage, leaves persisting until a new set has appeared.
Excavated trail a constructed trail that has a width greater than 1.5 m and a mineral soil cutbank height greater than 30 cm.
Extension services assistance provided to woodland operators. May include help with the preparation of forest management plans, cutting permits, marking trees for selective cutting, and guidance in carrying out slash disposal, site preparation, planting, etc.
Existing visual condition the present level of landscape alteration caused by resource development activities and expressed in terms of the visual quality objective categories.
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