Forestry Terms - V -
VEGETATION DENSITY: Number of individual plants of a given species in a unit of area. The relative density of a species is the percentage the number of its individuals is of the total number of individuals of all species in the sample.
VEGETATION HEIGHT: The vertical distance from ground level to the top of an individual plant or canopy.
VIRGIN TIMBER -Timber from an original forest that has not been previously disturbed or influenced by human activity. Many consider 150 year old trees virgin.
VISIBILITY SENSITIVITY: The determination of how rapidly visibility can be reduced.
VISUAL QUALITY: Degree of obstruction or contrast degradation of viewing scene due to air contaniments or weather.
VISUAL RANGE: The distance at which a large (half a degree) black or dark object disappears from view.
VISUAL RESOURCE MANAGEMENT CLASS: An assessment of the relative visual resource quality on National Forest system lands as it relates to potential resource use and or development. The five visual quality objectives, each representing a different degree of acceptable alteration of the natural appearing landscape are:
- Preservation: This visual quality objective allows ecological changes only. Management activities, except for very low visual-impact recreation facilities, are prohibited.
- Retention: This visual quality objective provides for management activities which are not visually evident. Under retention activities may only repeat form, line, color, and texture which are frequently found in the characteristic landscape. Changes in their qualities of size, amount, intensity, direction, pattern, etc., should not be evident.
- Partial Retention: Management activities are visually evident but subordinate to the characteristic landscape when managed according to the partial retention visual quality objective. Activities may repeat form, line, color, or texture common to the characteristic landscape but changes in their qualities of size, amount, intensity, direction, pattern, etc., remain visually subordinate to the characteristic landscape.
- Modification: Under the modification visual quality objective management activities may visually dominate the original characteristic landscape. However, activities of vegetative and land form alteration must borrow from naturally established form, line, color, or texture so completely and at such a scale that its visual characteristics are those of natural occurrences within the surrounding area or character type.
- Maximum Modification: Management activities of vegetative and landform alterations may dominate the characteristic landscape. However, when viewed as background, the visual characteristics must be those of natural occurrences within the surrounding area or character type. When viewed as foreground or middle ground, they may not appear to completely borrow from naturally established form, line, color, or texture. Alterations may also be out of scale or contain detail which is incongruent with natural occurrences as seen in foreground or middle ground.
