national forest.  Federally owned land managed to provide wood, water, and other uses for the benefit of the people of the United States. National forests are under the administration of the Forest Service of the U.S. Department of Agriculture.
          national park.  Federally owned land managed to maintain areas of outstanding and unique scenery and geographic features for public enjoyment. National parks are under the administration of the National Park Service of the U.S. Department of the Interior.
          natural thinning.  Death of trees in a stand as a result of competition.
          needle cast.  Premature browning and dropping of needles caused by a fungus. (Douglas-fir Christmas trees are particularly susceptible to Swiss needle cast.)
          nurse tree or crop.  A tree or crop of trees, shrubs, or other plants that foster another, generally more important, tree or crop. Syn. trainer.
          nutritive value.  A term usually prefixed by "high," "low," etc., to indicate relative quality of a given forage or feed to furnish elements valuable for animal nutrition.

O

          old growth.  A forest that has never been changed by management or harvesting. This term is misapplied by many to describe any forest that appears to be old. Individual trees in this type of forest are usually over 200 years old, and there are large standing and fallen dead trees throughout the stand.
          operation.  Used interchangeably for logging jobs, harvesting, cutting, milling, etc. An all-inclusive term for harvesting and hauling out the forest products.
          outplant.  Planting nursery-grown tree seedlings on a freshly prepared area. See transplant.
          overgrazing.  Grazing so heavy that it impairs future forage production and causes range deterioration through damage to plants, soil, or both.
          overmaturity.  That period in the life cycle of trees and stands when growth or value is declining. See maturity.
          overrun.  The excess lumber sawn from logs over the estimated volume or log scale, usually expressed in percent of log scale.
          overstocked.  A condition of the stand or forest, indicating more trees than desired, normal, or full stocking would require.
          overstory.  That portion of the trees is a stand forming the upper crown cover.           overtopped treeTrees with crowns entirely below the general level of the overstory cover, receiving no direct light either from above or from the sides. Syn. suppressed. See crown class.

A | B | C | D | E-F | G | H | I-K | L | M | N-O | P | R | S | T-X

Home Page