- Parent material
- The mineral or organic matter from which the upper layers of soil are formed.
- Park-like structure
- Stands with large scattered trees and open growing conditions, usually maintained
by natural ground fires.
- Partial retention
- A tree harvest method that removes only part of the stand. (See High
Grading.)
- Peak Flow
- The highest amount of stream of river flow occurring in a year, or from a single storm event.
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- Percolation
- Downward flow or infiltration of water through the pores or spaces of rock or
soil.
- Perennial stream
- A stream that flows throughout the year and from source to mouth.
- Personal use
- The use of a forest product, such as firewood, for home use and not for commercial
use.
- Planning area
- The area of National Forest land covered by a Regional Guide or Forest Plan.
- Planning period
- The 50 year time frame for which goods, services, and effects were projected
in the development of the Forest Plan.
- Pole/sapling
- The stage of forest succession in which trees are between 3 and 7 inches in diameter
and are the dominant vegetation.
- Pole timber
- Trees at least 5 inches in diameter, but smaller than the minimum size for sawtimber.
- Precommercial thinning
- Removing some of the trees from a stand that are too small to be sold for lumber
or house logs, so the remaining trees will grow faster.
- Prescribed fire
- Fire set intentionally in wildland fuels under prescribed conditions and circumstances.
Prescribed fire should be used to mitigate the suppression of natural fires.
- Prescription
- Management practices selected to accomplish specific land and resource management
objectives.
- Prognosis
- A computer model for timber growth and yield. It projects per-acre growth and
volume yield for commercial timber stands.
- Public domain lands
- The territory ceded to the Federal government by the original thirteen states,
plus additions by treaty, cession, purchase and theft.