Forestry Terms - D -
D.B.H. -Diameter at breast height.
DEBARKER -Machine for removing bark from logs or bolts.
-Machine used to remove the bark from roundwood prior to processing into chips, lumber, or
other wood products (8).
-See harvesting machine classifications, single function machines.
DECIDUOUS - perennial plants which are normally leafless for some time during the year.
DECK -Pile of logs on a landing. -Area or platform on which wood is placed.
DEFECT -Crook, conk, decay, split, sweep, or other injury that decreases the amount of
usable wood that can be obtained from a log.
DEFOLIATORS -Insects that destroy foliage. -Chemicals that cause plants to drop their
leaves .
DEGRADE -Any defect that lowers the grade or quality of a log.
DENDROLOGY -Study and identification of trees.
DELPETION ALLOWANCE -Deduction from taxable income derived from wasting asset. The
Internal Revenue Code of the United States permits the calculation of depletion allowances
either on the basis of a percentage of the gross income from the property in question or
on a per-unit-of-product basis. Depletion differs from depreciation in that the asset
subject to depletion cannot be replaced; a mine or an oil field cannot be replaced in the
same manner that a factory or machine can be replaced .
DEPTH TO BEDROCK OR RESTRICTION: The vertical distance from the mineral soil surface to unbroken solid rock or restriction.
DEPTH TO MOTTLING OR WATER: Mottling is the occurrence of small spots of color which contrast with the general matrix color of the soil. These spots of color, or mottles, commonly appear as small spherical splotches. Mottle colors are either: (1) gray on a matrix subsoil color of yellowish-brown, or (2) reddish-brown on a matrix subsoil color of gray or grayish-brown. The shorter the depth to mottling, the more poorly drained the soil.
DETRIMENTAL SOIL DISTURBANCE: The condition where established threshold values for soil properties are exceeded and result in significant change.
DIAMETER AT BREAST HEIGHT (d.b.h.): Tree d.b.h. is outside bark diameter at breast height. Breast height is defined as 4.5 feet (1.37m) above the forest floor on the uphill side of the tree. For the purposes of determining breast height, the forest floor includes the duff layer that may be present, but does not include unincorporated woody debris that may rise above the ground line.
DIAMETER, BASAL (Diameter at Root Collar): The straight line passing through the center of a cross section of a bole measured at the root collar of a shrub or tree.
DIAMETER, STUMP: The diameter of a tree inside or outside bark at stump height (generally one foot above the ground on the uphill side).
DIAMETER CLASSES -Classification of trees based on diameter outside bark measured at
d.b.h. In forest surveys, each diameterclass encompasses approximately 2 inches: the
6-inch class would include trees 5.0 through 6.9 inches in d.b.h.
DIAMETER INSIDE BARK -Diameter measurement of a standing tree or log in which the
estimated or actual thickness of the barkis discounted.
DIAMETER LIMIT -Maximum diameter of trees to be cut, as in a timber sales contract.
DIAMETER OUTSIDE BARK -Measurement of tree diameter in which the bark is included.
DIAMETER TAPE -Tape measure specially graduated so that diameter may be read directly when
the tape is placed around a
tree stem or log.
D.I.B. -Diameter inside bark.
DIBBLE -Spade-like tool used to prepare planting holes for seedlings. Dibbles are most
commonly used in the South but are
also used in other areas for planting containerized seedlings
DIRECTIONAL FELLING -Predetermining the way a tree will land when it hits the ground.
When shears are used, the wedge-shaped
blade provides a lever that directs the tree into its lay.
DIRECT SEEDING -Spreading seed s over the forest seedbed by hand or machine.
-Practice used to assist or supplement natural seed fall and to achieve regeneration.
DISSOLVED OXYGEN: A measure of the amount of oxygen dissolved in water. Expressed as mg/l of O2.
DOMINANT: The overstory life form or species in a plant community which contributes the most cover or basal area to the community, compared to other life form or species.
DOMINANT TREES: Trees or shrubs with crowns receiving full light from above and partly from the side; usually larger than the average trees or shrubs in the stand, with crowns that extend above the general level of the canopy and that are well developed but possibly somewhat crowded on the sides. A dominant tree is one which generally stands head and shoulders above all other trees in its vicinity. However, there may be a young, vigorous tree nearby, but not overtopped by a dominant tree. This smaller tree may be considerably shorter than the dominant, but still be receiving full light from above and partly from the sides. In its own immediate environment, it is dominant and should be recorded as such. Only understory trees immediately adjacent to the overstory tree will be assigned subordinate crown classes.
DOWN MATERIAL CONDITION: The deterioration of trees lying on the ground or across a stream. Classes include:
- Tree live. leaves green.
- Fresh killed. needles or leaves still on.
- Recent dead. Bark intact, limbs present, texture mostly sound, shape round, wood original color, elevated on support points.
- Intermediate. Bark loose, limbs ;missing, sapwood decay present, shape round, wood original to faded color, support all to mostly sagging.
- Decomposing. Bark absent, branch stubs loose, round to oval shape, color faded, all of piece on ground.
- Decomposed. Wood has deteriorated to punk or tinder.
DOYLE RULE -Log rule used in the Eastern and Southern United States. Underestimates
board footage in small logs and
overestimates in large logs.
