Timber Tree

Timber Tree any tree that produces wood of commercial importance. Wood is a material of plant origin characterised by fibrous structure and composed largely of lignin and cellulose. The high lignin content (25%) contributes unique rigidity to the structure and thus distinguishes wood from other plant materials.

Woods are classified in two groups: softwood and hard wood. Softwood is derived from the gymnospermous (mainly coniferous) plants and hardwood is derived from angiospermous (mainly dicotyledonous) plants.

Timber has versatile uses and plays a vital role in national economy. There are about 500 timber trees being grown in the forests and homesteads of Bangladesh. Most of them are hard woods except Podocarpus nerrifolius (banspata) which is the only softwood (gymnospermous wood) from Bangladesh. Some of the timber trees are as follows: Khair (Acacia catechu), Babla (A. nilotica), Kala koroi (A. lebbeck), Chatim (Alstonia scholaris), Boilam (Anisoptera scaphula), Itchri (Anogeissus acuminata), Kadam (Anthocephalus chinensis), Chapalish (Artocarpus chama), Kanthal (A. heterophyllus), Neem (Azadirachta indica), Shimul (Bombax ceiba), Kamdeb (Calophyllum polyanthum), Batna (Castanopsis tribuloides), Barun (Crataeva magna), Shisham (Dalbergia sissoo), Garjan (Dipterocarpus alatus), Tellya garjan (D. turbinatus), Sil Bhadi (Garuga pinnata), Gamari (Gmelina arborea), Sundari (Heritiera fomes), Telsur (Hopea odorata), Sidha (Lagerstroemia parviflora), Am (Mangifera indica), Bakain (Melia azedarach), Champaful (Michelia champaca), Tali (Palaquium polyanthum), Batna (Quercus spicata), Bhobinut (Samanea saman), Sal (Shorea robusta), Dharmara (Sterospermum personatum), Mahogony (Swietenia macrophylla and S. mahagony), Civit (Swintonia floribunda), Jam (Syzygium cumini), Dhaki jam (Syzygium grande), Teak (Tectona grandis), Toon (Toona ciliata), Goda (Vitex peduncularis), Arsol (V. pinnata), Lohakat (Xylia kerrii), and Passur (Xylocarpus mekongensis). [Md Khairul Alam]

Timber products Wood used in construction, furniture and paper pulp are all timbers and products produced or derived from them are timber products. Some monocotyledons produce woody stems, lack sapwood and heartwood, their products are specific eg bamboo products, cane products, etc. The products produced from the stems are often called timber products. Products produced/derived from woody parts of plants are termed as wood products. Products are source and origin oriented, all timbers are not suitable for all timber products or all purposes. Suitable timber species or timber parts are selected and judged from numerous variabilities for a specific product. Other products such as food, drink, oils, fibres, dyes, aromatics, cosmetics, medicines, plastics, resins, tannins, rayons, linens, rubbers, preservatives, insecticides, alkaloids, poisons, etc, produced from plants are called plant products or herbal products.

Among available growing timber species about 40% would be exotic. All are hardwoods except endemic and endangered conifer-banspata (Podocarpus neriifolia, family Podocarpaceae) and recently introduced conifer-Caribbean Pine or Pole Pine or Bangladesh Pine (Pinus caribaea var. honduransis, family Panacea); these are especially suitable for wood poles and paper pulp but supply is very limited. Paper is actually cellulose extracted from plant materials; quality depends on fineness and brightness of fibres. Papers are produced from muli bamboo (Melocanna baccifera) in Karnafuli Paper Mill, from sugarcane bagasse (Saccharum officinarum) in Paksi Paper Mill, from Gewa timber of Sundarbans (Excoecaria agallocha) in Khulna Newsprint Mill, and from Nalkhagra (Phragmites karka) and Malakana Koroi (Albizia falcataria) in Sylhet Paper Mill. Recently green jute plant (Corchorus capsularis and C. olitorius) are being used for making pulp. Besides these, there are several small private paper industries in Bangladesh run by local, imported and recycling materials.

When dense wood is crushed and compressed into board is called hard board which is used for making partitions, ceilings, etc. Such hard board is produced in Khulna Hard Board mill from Sundri Wood (Heritiera fomes). Thin slice of wood called veneer is used for making match boxes in different small industries in Bangladesh by using mainly Kadam (Anthocephalus cadamba), Chhatim (Alstonia scholaris) and Simul (Salmalia malabaricum) timber. When large veneers of odd numbers are glued and compressed together into board, the product is called plywood. Generally low cost timbers are used for making plywood, several alternative species are also available in Bangladesh but not plenty. Plywoods are used for making flush doors, ceilings, partitions and packing boxes.

These are produced by bangladesh forest industries development corporation (BFIDC) and other private organisations. Like plywood, a different type of board called particleboard or woodtex is also made from low cost wood particles. This product is also being manufactured by BFIDC. When prepared from particles of jute sticks, the product is called partex. It is prepared by M/S. Star Particle Board Industries. These boards are further decorated by covering with an attractive veneer produced mainly form Garjan (Dipterocarpus turbinatus) Teak or Shegun (Tectona grandis), Champa or Teak Chambul (Michelia champaca), Chapalish (Artocarpus chaplasha), Chickrosi (Chukrassia tabularis), etc. Usually low cost veneer is used for general purposes but for making attractive flush doors, tabletops, partitions, etc, attractive and expensive veneer of teak or teak chambul is used. These two species are highly priced due to their attractive grain, texture and figure. Teak Chambul is especially used for making veneer only.

Throughout Bangladesh, besides composite timbers, solid woods are used for internal domestic works such as in making doors, windows, furniture, cabinet, panel works, etc, the timber species Teak, Chapalish, Chickrasi, Gamari (Gmelina arborea), Sil Koroi (Albizia procera), Jarul (Lagerstroemia speciosa) are extensively used. For agricultural implements and boat building, localized timbers are traditionally used. Teak, Jarul and Sundari are used for making quality boats and launches, and Babla wood (Acacia nilotica) is used for making ploughs and carts. Garjan (Dipterocarpus species) is widely used for many purposes but without preservative treatment it is not enough durable.

The timber species Poa (Melia azadirach) is used for making musical instruments, and Gamari and Mehagoni are widely used for all small articles and toys because of their fine texture, workability and natural durability.

The rural electrification board (REB) is the largest consumer of preservative treated timber products. BFIDC is the only local producer of wood poles, produced from Sundari, Teak, Garjan, Civit and Tali; Debdaru and Kankra are also used to make poles. Electric meter boards and packings are prepared mainly from Mango, Rain tree, Kadam, Civit, Garjan and Bot woods (Ficus benghalensis); dozens of suitable timber species have been recently evaluated for these products. The Bangladesh Railway uses Garjan in making railway slippers; most of the wooden sleepers, however are imported. [Arun Kumar Lahiry]

See also woodworks.