P
palatability. The relative desirability of certain plants as forage for domestic and wild animals. Varies with composition of the plant cover or the season of grazing.
partial cut. A silvicultural cutting scheme that removes at any one time less than the total tree stand (selective cut, seed tree cut, shelterwood. cut).
particle-board. A type of board made by compressing chips or particles of wood under heat and pressure, in the presence of glue or resin. Flakeboard is a new product made by a similar process.
pathology, forest. The science that pertains to diseases of forest trees or stands, and to the deterioration of forest products by organisms.
peavey. A long-handled tool with a spike point and hinged arm; used to roll logs.
peeler core. A piece of roundwood that is a byproduct of the veneer-peeling process; usually 8 feet long and about 4 inches in diameter.
percent grade. 1. The vertical rise of land in 100 horizontal ft. A 16% grade means that in 100 ft horizontal, the elevation has changed 16 ft. Measured with an abney level or clinometer. 2. Amount of forest volume found to be in a given log grade.
percolation. The downward movement of water through the soil, primarily because of gravity.
pesticides. A general term for chemicals used to kill any of the pests of a desired crop.
phloem. An outer layer of tree tissue that conducts food from the leaves to the stem and roots.
photosynthesis. The conversion by green plants of light, water, and air into food energy.
pile and burnA controlled burn where the material to be disposed of is concentrated, usually with machinery, before burning.
piling. Round timbers driven into the ground to support other structures.
pistol buttApplied to trees with bases curving away from the slope and then upwards. This may indicate unstable or moving soil.
pitch. A term applied to the resin occurring in the wood of certain conifers.
pitch pocket. A well defined, lens-shaped opening between or within annual growth rings of coniferous wood, containing pitch and possibly bark.
planer. A machine used to put a smooth surface or shape on lumber.
plant. 1. To place young trees or cuttings in the soil on forest land; to establish a forest crop. Sometimes used loosely to include direct seeding. Trees may be placed as bare-root stock, or with roots within a ball of earth, or in earth within a container. 2. A processing facility for wood products.
plantation. An artificially reforested area established by planting or by direct seeding.
planting bar. A hand tool used in making a slit-hole in the soil in which trees are planted.
plot. A carefully measured area laid out for experimenta-tion or of mensuration; may be permanent or temporary. Syn. study plot.
plug seedling. A seedling grown in a small container, under carefully controlled environmental conditions. Seedlings are removed from containers for planting.
plywood. A wood product constructed of three or more layers of veneer joined with glue and (usually) laid with the grain of adjoining plies at right angles to one another.
pole. 1. A young tree between 5 and 12 in d.b.h. See sapling. 2. A log cut for the manufacture of power or telephone poles (involves trees larger than 12 in d.b.h.).
portable mill. A small sawmill that can be readily moved from one place to another. The usual daily capacity ranges from 3,000 to 10,000 board ft.
prebunch. In logging, to collect logs or other material at intermediate staging areas, in preparation for the main yarding operation.
precipitation. Deposits of atmospheric moisture in liquid or solid form, including rain, sleet, snow, hail, dew, or mist (also refers to quantity of water deposited).
precommercial thinning. Removal of some of the trees in a young stand to reduce competition for water and nutrients, and to accelerate commercial growth on remaining trees. Trees thinned from these stands have no commercial value.
preservation. 1. To maintain in an natural state; human impact on the biological system is minimized. Commonly refers to wilderness area management. 2. Wood preservation involves the protection of timber and wood products against the action of destructive living organisms, especially fungi, insects, and marine borers.
preservative. A substance that, when properly applied to wood, makes it resistant to attack by fungi, insects, or marineborers.
primitive area. An area of forest land that is left unaffected by human activities. These areas are in essence wilderness, but they are created by administrative regulation rather than by act of Congress.
prism. A wedge-shaped Piece of clear or amber-colored glass that is used to select trees for timber sampling.
pruning. The removal of live or dead branches from standing trees, whether done artificially or naturally. Natural pruning results from such causes as deficiency of light, decay, snow, ice, etc. Syn. self-pruning.
pulp, wood. Mechanically ground or chemically digested wood fibers used in the manufacture of paper and allied products. Bleached and purified wood pulp is also widely used in the manufacture of rayon and other chemicals.
pulpwood. Wood cut or prepared primarily for manufacture into wood pulp, for later manufacture into paper, fiberboard, or other products (the products depend largely on the species and the pulping process).
PUM yarding. Acronym for "pile unmerchantable material," referring to a U.S. Forest Service contract regulation that requires loggers to concen-trate all tops, chunks, and other unmerchantable material generated by harvesting. See YUM.
punky. A soft, weak, often spongy condition in wood; caused by decay.
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Forest Glossary