Glossary of Forestry Terms - V - W - Y

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Values-at-risk the specific or collective set of natural resources and man-made improvements/developments that have measurable or intrinsic worth and that could or may be destroyed or otherwise altered by fire in any given area.
Variable area plot sampling method a method of timber cruising commonly used for industrial timber cruising in which sampling area (plot size) varies with tree diameter.
Variable retention (dispersed, aggregate) Variable retention (dispersed, aggregate): a relatively new silvicultural system that follows nature's model by always retaining part of the forest after harvesting. Standing trees are left in a dispersed or aggregated form to meet objectives such as retaining old growth structure, habitat protection and visual quality. Variable retention retains structural features (snags, large woody debris, live trees of varying sizes and canopy levels) as habitat for a host of forest organisms. There are two types of variable retention:
  • Dispersed retention - retains individual trees scattered throughout a cutblock,
  • Aggregate (group) retention - retains trees in clumps or clusters.
The main objectives of variable retention are to retain the natural range of stand and forest structure and forest functions. With retention systems, forest areas to be retained are determined before deciding which areas will be cut. This system offers a range of retention levels. The system also provides for permanent retention of trees and other structures after regeneration is established. Variable retention can be implemented with a range of harvesting systems and can be combined with traditional silvicultural systems such as shelterwood or selection.
Vegetative lot quantity of vegetative material or vegetative propagules having the same species, source and year of collection.
Vegetative material plant parts or tissues used to produce vegetative propagules through asexual means.
Vegetative propagules plants produced through asexual means.
Ventilation Index (VI) a term commonly used in air pollution meteorology. The VI is a numerical value relating to the potential of the atmosphere to disperse airborne pollutants from a stationary source (such as smoke from a prescribed fire). It is calculated by multiplying the mixing height by the average wind speed in the mixed layer.
Veteran in growth and yield, a tree that is at least 30 years older than the age of the main stand. In multi-layered or complex-layered stands, a tree that is at least 100 years older than the oldest sample tree of the main stand.
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Viewshed a physiographic area composed of land, water, biotic, and cultural elements which may be viewed and mapped from one or more viewpoints and which has inherent scenic qualities and/or aesthetic values as determined by those who view it.
Visual Absorption Capability (VAC) The relative capacity of a landscape to absorb land-use alterations and still maintain its visual integrity.
Visual green-up See Greened-up.
Visual impact assessment an evaluation of the visual impact of resource development proposals on forest landscape.
Visual landscape analysis the process of recommending visual quality objectives based on the visual landscape inventory and social factors.
Visual landscape inventory the identification, classification, and recording of the location and quality of visual resources and values.
Visual landscape management the identification, assessment, design, and manipulation of the visual features or values of a landscape, and the consideration of these values in the integrated management of provincial forest and range lands.
Visual quality the character, condition, and quality of a scenic landscape or other visual resource and how it is perceived, preferred, or otherwise valued by the public.
Visual Quality Objective (VQO) an approved resource management objective that reflects a desired level of visual quality based on the physical and sociological characteristics of the area; refers to the degree of acceptable human alteration to the characteristic landscape.
Visual sensitivity a component of the visual landscape inventory that estimates the sensitivity of the landscape based on the visual prominence or importance of features, conditions that affect visual perception, and social factors that contribute to viewer perceptions.
Visually sensitive areas a table showing the estimated average tree or stand volume based on given tree measurements, usually diameter and height.
Volume table viewsheds that are visible from communities, public use areas, and travel corridors, including roadways and waterways, and any other viewpoint so identified through referral or planning processes.
Vulnerable species See Sensitive/vulnerable species.
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Waste the volume of timber left on the harvested area that should have been removed in accordance with the minimum utilization standards in the cutting authority. It forms part of the allowable annual cut for cut-control purposes.
Waste area a pre-approved site for disposal of excavations.
Waterbar a shallow ditch dug across a road at an angle to prevent excessive flow down the road surface and erosion of road surface materials. A small excavation across a road to collect and divert roadway surface water flow.
Water bomber See Airtanker.
Water management the planned development, distribution and use of water resources.
Water quality the physical, chemical and biological properties of water.
Water resources the supply of water in a given area or basin interpreted in terms of availability of surface and underground water.
Watercourse a natural stream or source or supply of water, whether usually containing water or not, such as a lake, river, creek, spring, ravine swamp, and gulch.
Watershed an area of land that collects and discharges water into a single main stream through a series of smaller tributaries.
Watershed assessment evaluates the present state of watersheds and the cumulative impact of proposed development on peak flows, suspended sediment, bedload, and stream channel stability within the watershed.
Watershed integrity refers to a stable overall physical condition of the watershed (bedrock, landforms, soils, drainage ways) within which transfers of energy, matter and, especially of water occur. It is prerequisite for the security of forest and stream ecosystems.
Watershed management the planned use of drainage basins in accordance with predetermined objectives.
Weeding a release treatment in stands during the seedling stage that eliminates of suppresses undesirable vegetation regardless of crown position.
Wetland a swamp, marsh or other similar area that supports natural vegetation that is distinct from adjacent upland areas.
Wilderness an area of land generally greater than 1000 ha that predominantly retains its natural character and on which the impact of man is transitory and, in the long run, substantially unnoticeable.
Wilderness area a part of the provincial forest designated by order in council as a wilderness area.
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Wildfire an unplanned or unwanted natural or human-caused fire, or a prescribed fire that threatens to escape its bounds.
Wildland urban interface a popular term used to describe an area where various structures (most notably private homes) and other human developments meet or are intermingled with forest and other vegetative fuel types.
Wildlife raptors, threatened species, endangered species, game animals, and other species of vertebrates prescribed as wildlife by regulation.
Wildlife habitat areas units of habitat recommended for the maintenance, enhancement, or restoration of red-listed wildlife, threatened, and endangered habitats, and those species identified as being regionally important.
Wildlife management the application of scientific and technical principles to wildlife populations and habitats to maintain such populations (particularly mammals, birds and fish) essentially for recreational and/or scientific purposes.
Wildlife trees dead, decaying, deteriorating, or other designated trees that provide present or future habitat for the maintenance or enhancement of wildlife.
Wildling a seedling naturally reproduced outside of a nursery, used in reforestation.
Windrow an accumulation of slash, branchwood and debris on a harvested cutblock created to clear the ground for regeneration. Also refers to an accumulation of fill or surfacing material left on the road shoulder as a result of grading operations.
Windthrow See Blowdown.
Winter range a range, usually at lower elevation, used by migratory deer, elk, caribou, moose, etc., during the winter months and typically better defined and smaller than summer range.
Wolf tree a dominant tree, which is often a remnant from a previous stand, having a broad crown and many limbs.
Woodlot the wooded portion of a private property upon which small-scale forestry operations are carried out.
Woodlot licence an agreement entered into under a Provincial Forest Act. It is similar to a Tree Farm Licence but on a smaller scale, and allows for small-scale forestry to be practised in a described area (Crown and private) on a sustained or perpetual yield basis.
Working plan See Management and Working Plans.
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Yarding the hauling of felled timber to the landing or temporary storage site from where trucks (usually) transport it to the mill site.
Yield Analysis the study of forest yield over time using mathematical models and inventory data.
Yield curve a representation of stand volume, usually as a function of stand age, in graphical or tabular form.
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