Forestry Terms - U -
UNDERSTORY - (a) The layer formed by the crowns of smaller trees in a forest.
(b) The trees beneath the forest canopy. -Foliage layer beneath the forest
-Young trees that are growing beneath the tall mature trees in a timber stand.
UNEVEN-AGED MANAGEMENT -Silvicultural system in which individual trees originate at different times and result in a forest with trees of all ages and sizes. Harvest cuts are on an individual-tree selection basis.
UNMERCHANTABLE WOOD -Material that is unsuitable for conversion to industrial wood products due to size, form, or quality. May include rough, rotten, and dead trees; the tops, limbs, and cull sections from harvested trees; or small and noncommercial trees.
UPPER STEM PORTION -Sawtimber tree bole extending from above the merchantable top to a minimum 4-inch top diameter outside bark or to the point where the central stems break into limbs.
URBAN AND SUBURBAN AREAS: Areas within the legal boundaries of cities and towns; suburban areas developed for residential, industrial, or recreational purposes; school yards; cemeteries; or other nonforest land not included in any other specified land use class.