Talus (Ped.). Fragments of rocks and other soil material accumulated by force of gravity at the foot of cliffs or steep slopes. (SSSA.).

Tape, Diameter. A specially graduated tape by means of which the diameter may be read directly when the tape is placed round a tree or log. (BCFT.).

Tape. Quarter-Girth. A specially graduated tape by means of which the quarter-girth may be read directly when the tape is placed round a tree or log. (BCFT.).

Taper. The decrease in diameter of the stem of a tree or of a log from the base to upwards. Cf. From

Taproot. The primary descending root formed in direct continuation of the radicle of the embryo; in trees, usually a stout root descending vertically from the centre of the tree. (BCFT.).

Taungya. (a) (Burmese; taung=hill; Ya= Cultivation). See Cultivation, shifting. (b) The term is now applied to the method of raising forest plantations in combination with field crops, otherwise known as Agri-silvi methods or Agri-silviculture, and to the plantations them-selves.

Telluric Moisture.(Ped.). Water present in a site. Derived from sources other than direct precipitation on the site, e.g., from seepage or springs. (BCFT.).

Temperate Climate. A climate which is warm in summer and has a definite winter season. Determined in India more by altitude than latitude. Cf. Subtropical climate.

Tending. Generally an operation carried out for the benefit of a forest crop, at any stage of its life; essentially covers operations on the crop itself and on competing vegetation, e.g., weeding, cleaning. thinning, and even improvement fellings; also pruning, climber cutting and girdling of unwanted growth, but not regeneration fellings, nor ground operations like soil working, drainage, irrigation and controlled burning. Cf. Cultural operations. (BCFT).

Teredo. A boring mollusc very destructive of wood in salt water. (BCFT).

Termite. A member of the order Isopetra. Syn. White ant. There are three ecological classes of termites :-

Damp wood. A termite which enters wood directly from the air at the time of swarming and has no contact with the ground, but which requires abundant moisture for its existence and consequently confines its activities largely to decaying wood.

Dry Wood. A termite which is exclusively wood inhabiting, never entering the ground and requiring but little moisture for its existence.

Subterranean. A termite which is essentially soil-inhabiting, entering wood only from the ground, and requiring a constant supply of moisture for its existence. It readily invades wood in contact with damp soil and is also able to build covered runways over impenetrable obstructions and thus reach wood removed from ground contact. (BCFT modif.).

Terracing (S.C.). Constructing a level or sloping platform of earth across a slope to detain or control surface run-off and check soil erosion. See Bench terraces.

Tetraploid (Genet.). Having four chromosome sets; the individual so constituted. (BCFT).

Thermograph. A self-registering thermometer.

Therophyte. (Ecol.) A class of Raunkiaer's life forms consisting of annuals or ephemerals passing unfavorable season as seeds and thus completing the life-cycle from germination to ripe seeds within a single growth period.

Thicket. (a) A crop composed of saplings. (b) A dense growth of small trees, bushes, bamboos etc. (BCFT).

Thinning. A felling made in an immature stand for the purpose of improving the growth and form of the trees that remain, without permanently breaking the canopy. (BCFT)

Thinning, Advance. Thinning done in a regular crop in anticipation of suppression; a method developed by Craib and O'Connor for waltle and pine plantations in S.Africa. Syn. Craib's thinning.

Thinning, Crown. A method in which thinning is primarily directed to the dominant trees in a regular crop, the less promising ones being removed in the interest of the best available individuals; the dominated and suppressed stems are retained unless they are dead, dying or diseased.

Thinning, Free. A method devised by Heak, in which attention is concentrated on evenly spaced selected stems (called elites or alpha stems) which are retained until maturity or till the last thinning or two thinning being directed to the removal of other stems hindering their optimum development. Applied to regular crops. Known in some placess, e.g., Madras and Andamans, as Elite thinning.

Thinning, Maximum. A method, developed by Gehrhardt, which is a further development on Heak's free thinning and like it aims at putting as high a proportion as possible of the total potential increment of the area on to the retained stems; from on early stage the number of such stems is limited to the minimum that can fully utilize the growing space. Applied to regular crops.

Thinning, Mechanical. A thinning in which the trees to be cut are selected by some rule-of-thumb, e.g.; trees in alternate rows or every second, third, fourth, etc. line, or a minimum spacing gauged by a standard stick ("stick thinning"). Applied to regular crops. Syn. Line thinning.

Thinning, Ordinary. The method in common use that consist in the removal of inferior individuals of a crop, starting from suppressed class, then taking the dominated class and lastly some of the dominant class. Applied to regular crops. Syn. Low thinning.

Thinning, Selection. (a) A method of thinning directed to obtain and/or maintain selection composition in a crop, with all diameter-classes adequately represented. (b) In American terminology, refers to a thinning in which the largest dominant trees and the poorest suppressed trees possessing a positive net conversion value or cut.

Thinning Cycle. The planned interval which elapses between successive thinning in the same area.

Thinning Grade. Refer to the relative extent to which a crop is opened up in thinning. Standard thinning grades are distinguished in ordinary and crown thinning with reference to the extent to which stem are removed. Cf. Thinning intensity.

Thinning Intensity. A term generally used to indicate in numerical terms the extent to which a crop is thinned.

Timber. (a) Categories of wood other than fire wood. (b) For statistical record, wood down to a minimum diameter or girth; 3 inches diameter over bark for small trees in the U.K. > 7 c.m.o.b. in Europe, and 8 in o.b. in India and Malaya. Timber volume is ordinarily exclusive of bark. See Timber Standard. (c) As variously described under any legal enactment. (BCFT modif)

Timber, Round. Timber in the log, i.e., unconverted timber; also prepared timber in the round, e.g. telegraph poles, pit-props, etc. (BCFT modif)

Timber Saw. Logs suitable in size and quality for the manufacture of sawn timber. Syn. Saw logs. (BCFT) Cf. Timber, sawn

Timber Sawn. Timber sawn to size, with or without wane. Syn Lumber (Am.) (BCFT)

Timber Standard (Mens.) Timber in round from the ground level down to 8 in. diameter o.b., volume being taken exclusive of bark.

Timbers, Primary. Species of timber that command a much higher price than others occurring with them and are therefore selectively exploited in preference to the latter. (BCFT). Cf. Timber secondary.

Timber Secondary. Species of timber that are unacceptable as primary but are nevertheless actually or potentially marketable. The term is derogatory and is deprecated (BCFT). Cf. Timbers, Primary.

Tolerance. (a) The capacity of a tree to develop and grow in the shade of, and in competition with, other trees. (b) The capacity to with-stand other factors as well as shade used in this sense, when some indication should always be given of the factor that is tolerated, e.g. shade tolerance, frost tolerance, etc. Cf. Exacting (BCFT modif.).

Ton (Cubic). In terms of timber volume, a unit of 40 cu. ft. of timber on which shipping freight rates are usually based. In India, Burma and Malaya the ton is treated as equal to 50 cu. ft. of sawn timber or 50 hoppus feet of round timber that latter known as hoppus ton.

In terms of weight, a ton=2240 avoirdupois, and this is known as the long ton.

1 short ton=2000 lb. avoirdupois=0.9072 metric ton.

1 metric ton=1000 kilogrammes = 1.102 short ton. = 0.9842 long ton.

Top, To. To cut off part or all of the crown of a tree. (BCFT).

Topocline (Genet.) A cline in respect of topographic factors. Cf. Ecocline. (BCFT).

Topographic Factors. Those pertaining to the configuration of the land surface, viz, altitude, slope, aspect and exposure.

Transect. A line, belt, strip or profile, as of vegetation chosen for study and charting. Cf. Vegetation profile. (BCFT modif)

Translocation. The movement of food and other materials within the tissues of a plant. (BCFT)

Transpiration. The process by which water vapour leaves the foliage or other parts of a living plant and is released to the atmosphere.(BCFT)

Transplant. A seedling after it has been moved one or more times in a nursery in contrast to a seedling planted out direct from the seedling. (BCFT). Cf Seedling.

Transplant To. To move nursery stock from one part of the nursery to another in order to obtain young trees suitable for planting out. (BCFT). Cf. Line out, to; Prickout. to (Use of the term in the sense of planting out is dying out and is deprecated).

Tree. (a) A large woody perennial plant having a single well-defined crown. Cf. Shrub. (b) As a legel term defined in forest law it includes not only trees as defined above, but also plants as shrub, bamboos, canes and even stumps and brushwood. (c) The stage of growth beyond the pole stages, when the rate of height growth being to slow down and crown expansion becomes marked.

Tree, Elite. (a) A tree selected for seed collection or for vegetative propagation on account of some specially good quantity it may possess such as exceptional rate of growth, fine form, or timber quality and resistance to adverse climatic factors and to diseases and pests. (BCFT). Cf. Stand, elite. (b). A tree selected for retention till maturity or till the last thinning or two under a regime of Heak's Free thinning or Gehrhardt's Maximum thinning Syn. Alpha tree or stem.

Tree, Nurse. A tree grown or retained to protect or foster the growth of other trees during their youth (BCFT).

Tree, Protected. One set apart as a good example of an important species for preservation as long as possible.

Tree, Reserved. (a) A selected tree temporarily retained in a crop that is being regenerated for some specific purpose, e.g., to give seed, to protect regeneration or to put on increment. (b) A tree or species in which a government has reserved special proprietary right under a Forest Act or other law and the felling of which is prohibited except under rule. Cf. Tree royal. (BCFT modif.)

Tree, Royal. A kind of reserved tree which is the property of government wherever it may stand, e.g., teak in Burma and Sandalwood in Mysore. (BCFT modif)

Tree, Sample. A tree chosen as representative of a given population for detailed study of one or more of its characteristics. (BCFT). As selected in sample plot work in India, it is a tree whose diameter is equal or nearly equal to the mean diameter of the group it represents, and whose height, stem form and crown are also typical of the group.

Tree Trap. A dead or girdled standing tree left to attract insects and facilitate their destruction. Syn Trap Stem. Cf. Log trap. (BCFT).

Tree Weed. A tree of a species having little or no economic value on the site in question.

Tree Wolf. A vigorous tree, usually of bad form, occupying more space than its future value warrants and threatening potentially better neighbors; usually a broad-crowned dominants. (BCFT)

Tree Class. Any one of the classes into which the trees of a stand or crop may be divided for a variety of purposes. Cf. Stem class; Crown class. (BCFT)

Tree Compass. An instrument of special design used for measurement of the diameter of tree or log.

Triangular Planting. Planting in the pattern of an equilateral, triangle. e.g., with the plants occupying the three corners of each of adjacent equilateral triangles.

Trim, To. (a) To cut of branches from a felled or fallen tree. (b) To remove the buds and side shoots from young trees.

Triploid (Genet.). Having three chromosome sets; the individual so constituted. (BCFT).

Tropical Climate. A climate which is not very hot without a definite winter season.

Tropism. The response of an organism to an external stimulus by turning or bending. (BCFT)

Tropophyte. A plant that is adapted to a climate in which a very dry season is followed by a wet one, and is, therefore, alternately xerophilous and hygrophilous.

Truncated Soil Profile. A soil profile that has lost its upper horizon(s) through erosion (BCFT)

Tundra. The zone of low vegetation in an arctic climate between the limit if the tree zone and perpetual ice or snow ; mountain or alpine tundra is the term sometime used for the corresponding zone on high mountains (BCFT)

Type Specimen. One designated as the standard of a taxonomic group. (BCFT)