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Tending
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Generally, any operation carried out for the benefit
of a forest crop or an individual thereof, at any stage of its
life; covers operations both on the crop itself, e.g., thinnings
and improvement cuttings, and on competing vegetation, e.g., weeding,
cleaning, and girdling of unwanted growth, but not regeneration
cuttings or site preparation. Any operation carried out for the benefit of an established forest crop at any stage of its life (e.g. cleaning, thinning, fertilizing, spraying).
Terminal Bud
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A bud that develops at the apex of a stem. Also known as apical bud.
Terminal Bud Scar
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A ring of thickened bark on a twig, indicating where the terminal bud grew the previous year.
Thinning
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A cutting made in an immature crop or stand primarily
to accelerate diameter increment but also, by suitable selection,
to improve the average form of the trees that remain. (Defined
in Nova Scotia as a spacing operation designed primarily to recover
potential mortality and to improve growth, quality, and percentage
of desirable trees.)
- commercial thinning: A thinning in which harvested
trees are removed from the site and used for commercial purposes.
- crown thinning: The removal of trees from the dominant
and codominant crown classes to favour the best trees of those
same crown classes. (1)(Defined in Nova Scotia as the removal
of trees from the dominant and codominant crown classes to promote
the growth of desirable trees and species.)
- free thinning: The removal of trees to control stand
spacing and favour desired trees using a combination of thinning
criteria without regard to crown position.
- low thinning: The removal of trees from the lower crown
classes to favour those in the upper crown classes.
- mechanical thinning: Thinning involving removal of
trees in rows or strips, or by using fixed spacing intervals.
- precommercial thinning (PCT): A thinning that does
not yield trees of commercial value, usually designed to improve
crop spacing.
- row thinning: A thinning in which the trees are cut
out in lines or narrow strips at fixed intervals throughout a
stand.
- selection thinning: The removal of trees in the dominant
crown class in order to favour trees in the lower crown classes.
- spacing: A thinning in which trees at fixed intervals
of distance are chosen for retention and all others are cut.
Thinning Cycle
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The time interval between thinnings in the
same stand.
Thinning From Above
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see Thinning: crown
Thinning From Below
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see Thinning: low
Thinning Grade
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The severity of low thinning based on the
crown classes removed, ranging from very light (Grade A) to very
heavy (Grade E).
Thinning Intensity
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The characteristics of a thinning prescription
in terms of the severity and frequency of thinning entries.
Thinning Series
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Two or more adjacent forest plots that
are thinned differently (e.g., to different thinning grades),
essentially so as to compare the increment of individual stems
(This term is not used in Manitoba or Saskatchewan when the treatment
precedes direct seeding or planting.)
Timber Stand Improvement (TSI)
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A term comprising all intermediate
treatments made to improve the composition, structure, condition,
and increment of either an even- or uneven-aged stand.
Tissue Culture
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A blanket term for the cultivation of plant
or animal tissues in a controlled artificial environment on defined
media under aseptic conditions.
Tolerance
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The ability of an organism or biological process
to subsist under a given set of environmental conditions. The
range of these under which it can subsist, representing its limits
of tolerance, is termed its ecological amplitude. For
trees, the tolerance of most practical importance is their ability
to grow satisfactorily in the shade of and in competition with
other trees.
Toxicity
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The degree to which a substance is harmful or poisonous.
Tracheids
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An elongate, spindle-shaped xylem cell, lacking protoplasm at maturity.
Trainer
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A tree beneath the main canopy which by its shading
and/or abrasive action hastens the natural pruning or improves
the form of some other tree.
Transpiration
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The passage of a gas or liquid (in the form of vapour) through the skin, a membrane, or other tissue.
Transplant
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A seedling that has been replanted one or more
times in a nursery to improve its size and growth potential characteristics.
Also a tree that is moved from one place to another.
Tree
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A woody plant having a well-defined stem and more or less definitely formed crown and usually attaining a height of at least 3 m.
Tree Breeding
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see Forest Tree Breeding
Tree Improvement
-
see Forest Tree Improvement
Tree Marking
-
Selection and indication, usually by marking
with paint on the stem, of trees to be felled or retained.
Two-Aged Stand
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A stand containing two distinct age classes
differing by more than 20% of the rotation age.
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