ForestrypediaLexicon of Forestry (LoF)

T | Lexicon of Forestry

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Tail tree: In skyline logging, a tree used to anchor the mainline away from the landing.
Tally: The count of trees, logs, or other products; to count trees, logs, or other products; to record products, distances, etc., as measured.
Tan/ Tannin: A brownish or yellowish compound found in plants. Use: tanning, dyes, astringents
Tape, Fiberglass: A girth tape measures diameter indirectly. The tape is wrapped around the tree to measure circumference. This value is divided by PI (3.1415….) to estimate diameter. Often the tape will have normal units (mm and cm) on one side and PI units on the other side.
The tape should be held relatively firmly (but avoid stretching). The tape should also be wrapped around the bole in a perpendicular plane to the stem axis. Keeping the tape numbers right side up (as in the photograph) reduces the chances of incorrectly reading the scale – when upside down errors like x.4 being recorded as x.6 are common.
Tapestry hedge: A closely spaced row of mixed species of shrub.
Taper: The gradual reduction of diameter in a stem of a tree or a log from the base to the top.
Taphrina: It is fungal genus within the Ascomycota that causes leaf and catkin curl diseases and witch’s brooms of certain flowering plants
Taproot: The major tree root with the greatest tendency to grow downward. Depending on the species and soil conditions, the taproot may or may not be pronounced or show heavy branching.
Tarif table: A tree-volume table based on d.b.h. and total height.
Taungya plantation: The raising of a forest crop in conjunction with a temporary agricultural crop.
Technical rotation: The rotation under which a spp yields most material of specified sizes and suitability for economic conversion of special uses.
Telerelaskop: A research quality instrument that is no longer in production. The Telereskop is similar in principle to the [Relaskop] except that it includes 5 x optical magnification.
Telial stage (telium): A stage of the rust fungi; a fruiting structure usually appearing as fine, hairlike projections from lower surfaces of infected leaves.
Tending: 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.
Tending felling: An operation comprising cleanings and thinnings. 
Terminal bud: The uppermost bud on the main stem of a tree. (See leader).
Termite: Common name for numerous species of social insects that can damage wooden structures such as furniture or houses. Termites mostly feed on dead plant material, generally in the form of wood, leaf litter, soil, or animal dung, and about 10% of the estimated 4,000 species (about 2,600 taxonomically known) are economically significant as pests that can cause serious structural damage to buildings, crops or plantation forests., most are distributed in tropical countries and some inhabit the temperate regions. Termites are widely distributed throughout Pakistan. In Pakistan, 89 spp are native.
Termite Colony: Termite colonies, or termitaries, range in size from several hundred to several million individuals. Common in tropical rainforests, there may be from several dozens to several thousand termitaries per acre of forest. Many species of termites have a caste system, consisting of reproductive individuals, workers, and soldiers. The workers build the nest and provide food and grooming for the greatly enlarged egg-laying female and all other colony members. The soldiers provide protection for the colony, while the reproductive pair ensures a constant supply of eggs. In many species, egg production may approach 30,000 eggs per day.
Terrace: A flat, fairly narrow, level strip of ground, bounded by a vertical or steep slope and constructed on a hillside so that the land can be cultivated
Territory: An area occupied by an animal or group of animals and defended against the members of the same spp.
Thickening: Thickening of vegetation is a change in carbon per unit area arising from human induced changes in grazing or fire regimes. Vegetation thickening usually involves an increase in the biomass of woody plants, (measured as an increase in basal area and height) and often a simultaneous increase in soil carbon and dead plant material. It typically results from an increase in grazing intensity and constancy, which per unit area lead, along with other management actions, to a decrease in the frequency and intensity of fires. The species of woody plants involved may be native or exotic.
Thicket: A dense growth of small trees or bushes. 
Thicket stage: See stand development
Thinning: 1. A partial cut in an immature, overstocked stand of trees used to increase the stand’s value growth by concentrating on individuals with the best potential. 2. Cutting in an immature stand to increase the growth rate of the leave trees. The goal is to foster quality growth, improve composition, promote sanitation, and recover and use material that would otherwise be lost to mortality. Thinning does not generally increase per-acre cubic-volume growth, but it can increase board-foot yield. Chemical thinning:   Any thinning in which the unwanted trees are killed by treatment with herbicide. 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 favor the best trees of those same crown classes. Free thinning:  The removal of trees to control stand spacing and favor 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 favor 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 generally in plantations 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 favor trees in the lower crown classes. Selective thinning:   A thinning in which trees are removed or retained on their individual merits. Spacing: A thinning in which trees at fixed intervals of distance are chosen for retention and all others are cut. 
Thinning cycle: The time interval between thinnings in the same stand.
Thinning frequency: See thinning cycle
Thinning from above: See thinning: crown
Thinning from below: See thinning: low
Thinning grade: The severity of low thinning based on the crown classes removed, ranging from very light (Grade A) to very heavy (Grade E). 
Thinning intensity: A measure of the combined effect of thinning weight and thinning frequency, in terms of the volume removed during any succession of thinnings, sometimes expressed as an average annual stand depletion by dividing their total thinning weight by the number of years they cover. 
Thinning interval: See thinning cycle
Thinning out: Removal of seedling or sapling in excess in a young stand in order to favor residual tree development.
Thinning regime: A term comprising the type, degree, and frequency of thinning for a given area, generally along with the year of commencement and sometimes termination.
Thinning series: 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
Thinning shock: A condition of very slow growth in a thinned stand, usually from a heavy thinning that exposes residual trees to conditions much different from those present before thinning.
Thinning, types of: (See also commercial thinning, pre-commercial thinning). 1. Low thinning: The removal of trees from the lower crown classes in a stand. (Syn. thinning from below). 2. Crown thinning: The removal of trees from the middle and upper crown classes in a stand, to favor the most promising trees of these classes. (Syn. thinning from above). 3. Selection thinning: Removal of dominant trees to benefit trees in lower crown classes. 4. Free thinning: Removal of trees to benefit best trees, regardless of crown class. 5. Mechanical thinning: Removal of trees based totally on their spacing or arrangement.
Thinning weight: A degree of thinning expressed in terms of the volume removed at any one time.
Threatened species: 1. A species or subspecies whose population is so small or is declining so rapidly that it may become endangered in all or a significant portion of its range. 2. A species that is still abundant in some parts of its range but the continuity or existence of the species in the log run is questionable because the number of individuals and population has declined significantly in other areas.     
Thorax: The body region behind the head, which bears wings and true (jointed) legs if present.
Tidal wave: The correct word for the big wave people often call ‘tidal waves’ is tsunami. True ‘tidal waves’ – or waves caused by the tides – are the ordinary waves people see on the ocean.
Tie ridge: In contour furrowing and trenching, a narrow strip of ground left unexcavated so as to break the horizontal continuity of the trenching and thus contain and properly distribute any precipitation.
Timber: 1. A log having diameter of 8 in. at thin end side and length of greater than 8 ft. (compare Billet) 2. A term loosely applied to forest stands or their products; often applied to wood in forms suitable for heavy construction (houses, ships, bridges).
Timber cruise: See cruise.
Timber marking: See tree marking
Timber Stand improvement (T.S.I.): Any practice that increases the value or rate of value growth in a stand of potential sawtimber trees. Pruning and thinning are considered T.S.I.
Timber type: See forest type.
Tine cultivator: See tine plough
Tine harrow: See tine plough
Tine plough: A plough in which the leading edge of the landside is extended forward and downward as a tine-bearing replaceable sock. 
Tissue culture: A general term for the cultivation of plant or animal tissues in a controlled artificial environment on defined media under aseptic conditions.
T-notching: See slit planting
Tolerance: Capacity of a tree or plant to develop & grow in the shade of (and in competition with) other trees or plants; a general term for the relative ability of a species to survive a deficiency of an essential growth requirement (light, moisture, nutrient supply).
Top diameter: In standing tees, the diameter at the top of a merchantable length of the stem.
Top dressing: Surface application of fertilizers or organic ameliorants to crops after establishment or onto land after physical preparation for planting.
Topography: area’s features: the features on the surface of an area of land; mapping of surface features: the study and mapping of the features on the surface of land, including natural features such as mountains and rivers and constructed features such as highways and railroads
Top pruning: See pruning: high
Total yield: The standing volume of a crop plus the total volume removed in thinning since its establishment as a more or less even-aged stand.
Trainer: (See: Nurse Tree or crop)
Trametes: It is a genus of fungi that is distinguished by a pileate basidiocarp, di- to trimitic hyphal systems, smooth non-dextrinoid spores, and a hymenium usually without true hymenial cystidia.
Transpiration: The process by which water vapor leaves a living plant and enters the atmosphere.
Transplant: 1. To replant a nursery seedling in another part of the nursery for further development. A “2-1” tree seedling is one that was grown from seed for 2 years in the nursery, then replanted and left for a year in another nursery bed. 2. To move a wild seedling to another location for regenerating a forest. 3. Any seedling that is removed from one location and planted elsewhere.
Transplanter: See transplanting machine
Transplanting: An operation consisting of moving the nursery stock from one part of a nursery to another, essentially so as to improve its root development before forest planting. 
Transplanting board: A simple device having regularly spaced slots for the individual plants so as to ensure proper spacing and lining out in the new bed. 
Transplanting machine: An implement used to line out transplants in a nursery.
Transplanting plough: A plough used in the nursery to open trench for the roots of plants being lined out, while simultaneously backfilling it. 
Tree: A woody plant having one well-defined stem and a more or less definitely formed crown, usually attaining a height of at least 8 ft.
Tree age: The number of years since the germination of the seed, or the budding of the sprout or root sucker.
Tree breeding: See forest tree breeding
Tree class: Any class into which the trees forming a crop or stand may be divided for a variety of purposes. 
Tree farm: A privately owned forest managed on a multiple use basis with timber production as an important management goal.
Tree improvement: See forest tree improvement
Tree injection: The deliberate introduction, by pressure or simple absorption of a chemical — generally a water-soluble salt in solution — into the sapstream of a living tree. 
Tree injector: A specially designed tool used to inject a solution into a living tree.
Tree length: Entire length of tree, or with the top lopped off at small diameter, as in skidding tree length to a landing for bucking into logs.
Tree marking: Selection and indication, usually by marking with paint on the stem, of trees to be felled or retained.
Tree nursery: See nursery
Tree planter: See planting machine
Tree-planting machine: See planting machine
Tree shaker: A machine designed to shake a tree in order to dislodge its fruits for collection from the ground.
Tree spacing: The distance between trees, which is most often regulated at the time of planting or during a harvest or thinning operation. Spacing, like stand density, affects understory vegetation, seed production, growth rate, and wildlife habitat.
Tree spade: Hydraulic accessory attached to a machine used for transplanting landscape stock.
Tree surgery: The care and repair of trees valued for amenity.
Trench: Small channel in Irrigated Layout that waters a Slot. Its dimensions are: depth 12 in. and width 9 in. The distance b/w two trenches is 10 ft.
Trencher: In a planting machine, a metal shoe behind the share, this makes the trench for the plant roots. 
Trenching: Site preparation technique creating a more or less continuous furrow, with surface debris, duff, and low vegetation scattered to one side, using shaping devices pulled or often hydraulically powered by a prime mover.
Trench planting: Setting out young trees in a shallow trench or a continuous slit. 
Trim allowance: The extra 2 or 3 inched left on a bucked log to allow logs with end checks, pulls, or slanting buck cuts to be trimmed to standard lumber lengths.
Trimming: Removing the side buds and side shoots from a young plant. Cutting a felled or fallen and sometimes a standing stem clear of branches and stubs. 
Trout: Common name for many species of fish belonging to the salmon family. Some, called sea trout, are anadromous—that is, they ascend the rivers from the sea to breed.
Tsunami: One or a series of huge sea waves caused by earthquakes or other large-scale disturbance of the ocean floor. (Referred to incorrectly by many as a tidal wave, but these waves have nothing to do with tides.) The word tsunami is Japanese, meaning ‘harbor wave.’

Tubed seedling: See seedling: container
Tube planting: Setting out young trees in narrow, open-ended cylinders of various materials, in which they have been raised from seed or into which they have been transplanted.
Tuberculosis: Tubercle-forming disease: an infectious disease that causes small rounded swellings tubercles to form on mucous membranes, especially a disease pulmonary tuberculosis that affects the lungs
Tuft: Bunching of twigs or needles.
Turn: The logs brought to the landing during a single yarding or skidding cycle.
Turnup: In Christmas tree culture, the practice of leaving a green branch when harvesting a Christmas tree; this branch, turned upwards, becomes the next tree. (Syn. stump culture).
Turpentine: A colorless, flammable, strong-smelling essential oil. Use: paint solvent, in medicine; Turpentine, name applied to numerous semi-fluid, yellow or brownish oleoresins obtained from various coniferous trees in Asia, Europe, and America. Oil of turpentine is the principal product of turpentine, and it is widely used as a solvent and thinner for various oil paints and varnishes, to which it gives consistency and drying properties. Medically, oil of turpentine acts as a powerful stimulant and is often used as an antispasmodic and astringent. It is also capable of destroying various intestinal parasites and exhibits powerful diuretic properties.
Two-furrow plough: A plough with two moldboards turning the furrow slices to the same side. 
Two-rotation coppice system: See coppice-of-two-rotations method
Two-stage cutting (felling): See shelterwood cutting
Two-storied high-forest system: An accessory system in which a crop of a different species is introduced (i.e., artificially) beneath an existing immature crop, the two crops eventually being harvested together, or the upper one before the lower. 
Two-storied stand: A forest stand in which two height classes of considerable difference occur, the overstory and understory. The term is not applicable to a forest in process of reproduction, in which the appearance of two stories is due to a seed tree or shelterwood cut before final cut.
Tylosis:  1. A sac that forms in the water-conducting vessels of the older wood of a tree, often in response to drought or disease. Tylosis may cause blockage, and often fill with resins, gums, or pigments that may help to preserve, strengthen, or color the wood or provide a source of dyes. 2. Outgrowth of a cell membrane from a ray or axial parenchyma cell through a pit in a xylem vessel wall into the vessel, partially or completely blocking the lumen of the vessel.

Typhoid: Infectious disease of the digestive system: a serious and sometimes fatal bacterial infection of the digestive system, caused by ingesting food or water contaminated with the bacillus Salmonella typhi. It causes fever, severe abdominal pain, and sometimes intestinal bleeding.
Corrections and Suggestions are most welcome. Please use the comment section for feedback. If you see any missing terminology or any updated one or any latest term please use the comment section for the purpose. Also, if you have any image or data related to any above terminologies, don’t forget to mail me at
Naeem Javid Muhammad Hassani

Naeem Javid Muhammad Hassani is working as Conservator of Forests in Balochistan Forest & Wildlife Department (BFWD). He is the CEO of Tech Urdu ( Forestrypedia (, All Pak Notifications (, Essayspedia, etc & their YouTube Channels). He is an Environmentalist, Blogger, YouTuber, Developer & Vlogger.

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