Silvicultural Terms in Canada

underbrush [sous-bois (n.m.)]
	Shrubby vegetation and stands of tree species that do not produce commercial timber. (3)

undercutting [cernage (n.m.)]
	Root-pruning of nursery stock in situ, particularly by horizontal cut. (3)

undergrowth [sous-bois (n.m.)]
	A general term usually comprising both the herbaceous cover and the lower shrubs, and even the lowest trees, under a forest canopy. (3)

underplanting [plantation en sous-étage (n.f.)]
	Planting young trees under the canopy of an existing stand.

understory protection [protection du sous-étage (n.f.)]
	Removal of mature trees while damage to the understory is kept to a minimum.

undesirable species [essences indésirables (n.f.)]
	Species that conflict with or do not contribute to the management objectives. (19)

uneven-aged [inéquienne (adj.)]

Of a forest, stand, or forest type in which intermingling trees differ markedly in age. The differences in age permitted in an uneven-aged stand are usually greater than 10-20 years. (5)

Usually form more than three distinct age classes.

cf. even-aged

uneven-aged system [régime inéquienne (n.m.)]
	A silvicultural system in which stands have an uneven-aged structure. (1)

uniform system [mode de régénération par coupes progressives uniformes (n.m.)]
	See shelterwood cutting: uniform shelterwood system

unmerchantable [non marchand (adj.)]
	Of a tree or stand that has not attained sufficient size, quality, and/or volume to make it suitable for harvesting. (5)

variety [variété (n.f.)]
	1. A taxonomic subdivision of a species based on minor characteristics and often on exclusive geographic range. 2. An assemblage of cultivated individuals distinguished by any useful, reproducible (sexual or asexual) characters. (25)

vegetative propagation [multiplication végétative (n.f.)]
	Reproduction by other than sexually produced seed. Includes grafting, budding, rooting of cuttings, and tissue and cell culture, including embryogenesis.

veteran [vétéran (n.m.)]
	A tree that has escaped logging, windthrow, or fire, and occupies a dominant position in the stand. (3)

viability [viabilité (n.f.)]
	Of a seed, spore, or pollen grain, its capacity to germinate and develop, under given conditions. (3)

vigor class [classe de vigueur (n.f.)]
	Assumption of the health of a tree based on observation of the foliage. (10)

virgin forest [forêt vierge (n.f.)]
	Natural forest, the development of which has been virtually uninfluenced by modern human activity.

volunteer growth [régénération subséquente]
	Natural regeneration following site preparation and seeding or planting that could either supplement or completely obscure the trees being planted or seeded on the area.

wedge system [mode de régénération par coupes progressives en coin (n.m.)]
	A modification of the strip shelterwood system in which cuttings begin as narrow, interior, wedge-shaped strips with the apex into the prevailing wind, and are then successively enlarged and advanced; regeneration is mainly natural; regeneration interval is short and the young crop fairly even-aged. (3)

weeding [désherbage (n.m.)]
	A release treatment in stands during the seedling stage that eliminates or suppresses undesirable vegetation regardless of crown position. (1)

weed tree [indésirable (n.m.)]
	Any tree of a species having little or no economic value on the site in question. (3)

whip [fouet (n.m.)]
	1. A bare-root hardwood planting stock. 2. Any slender tree that the wind causes to lacerate the crowns of its neighbors. (3)

wildland [friche (n.f.)]
	Uncultivated land other than fallow. Land currently little influenced by human activity.

wildling [semis naturel (n.m.)]
	syn.: wilding, wild seedling A naturally grown, in contrast to a nursery-raised, seedling, sometimes used in forest planting when nursery stock is scarce. (3)

wind bend [courbé par le vent (adj.)]
	Condition of trees having a curved stem as a consequence of wind action or compression due to heavy load on the crown of the tree. cf. windfirm

windbreak [brise-vent (n.m.)]
	A small-scale shelterbelt or other barrier, natural or artificial, maintained against the wind. (3)

windfall [chablis (n.m.)]
	1. A tree or trees thrown down or with their stems broken off or other parts blown down by the wind. 2. Any area on which the trees have been thrown down or broken by the wind. (3)

windfirm [stable au vent (adj.)]
	Of trees, able to withstand strong winds, i.e., to resist windthrow, windrocking, and major breakage. Such trees may not remain upright but show wind lean or wind bend or both. (3)

wind lean [couché par le vent (adj.)]
	Condition of trees having a leaning stem, result of partial uprooting or wind action. cf. windfirm

wind rock [balancement au vent (n.m.)]
	Movement of tree stems in the wind, which may lead to chafing of the collar and sometimes of the roots, and, in very wet soil, loosening of the ground. (3)

windrow [andain (n.m.)]
	Slash, brushwood, etc., concentrated along a line so as to clear the intervening ground between two of them. (2)

windrow planting [plantation sur entrandain (n.f.)]
	Planting between the two lanes created in windrowing. (3)

windthrow [déracinement par le vent (n.m.)]
	1. Uprooting by the wind. 2. Tree or trees so uprooted. (3)

wolf tree [arbre loup (n.m.)]
	A tree, generally overtopping and of poor form, that occupies more growing space than its commercial value warrants. (1)

working group [section d'aménagement (n.f.)]
	An aggregate of forest stands, or forest stand and forest sites, which are grouped for the purpose of applying a common set of silvicultural treatments (also called operational group).

yield table [table de rendement (n.f.)]

Tables and graphs illustrating volumes per hectare of stands at a specific age.

normal yield table [table de rendement normal]: Estimated stand volume per age class at normal stocking.

empirical yield table [table de rendement empirique]: Representation of actual and forecast volumes at different stocking levels per age class.

underplant [plant de sous-étage (n.m.)]
	Young trees used for underplanting. (3)

understocking [de densité relative déficiente (n.f.)]
	See stocking: NSR

uniform shelterwood [coupes progressives uniformes (n.f.)]
	See shelterwood cutting

yearling [semis de l'année (n.m.)]
	A one-year-old seedling. (3)