5.06.02 - Utilization of planted teak
The mission of this Working Party is the utilization of teak timber produced within the framework of socially and environmentally acceptable norms of Sustainable Forest Management (SFM).
While it aims to promote all teak wood research programmes, the following objectives were defined for targetted research:
- Identification of superior planting stock / reproductive material from different provenances/countries/genetically improved strains to produce quality timber
- Characterisation and industrial/market standardisation of juvenile wood produced in intensively managed plantations
- Developing models for prediction of intensive silvicultural and genetic improvement techniques on timber quality/market (end-product) value of teak wood.
As some of the above research activities will be of relatively long-term nature, the following research agenda is considered to be of immediate priority for formulation and co-ordination of the international cooperative projects by mobilisation of national/international financial resources for possible support: Utilisation (properties and processing) of juvenile and /or sap wood available from thinnings of teak plantations and establishment of grading/quality standards for improved market-value of small dimensional teak timber.
State of Knowledge
Teak constitutes about 75% of high quality hardwood plantations that attracts investor's attention on plantation programs in the context of sustainable forest management (SFM) in many tropical countries including Latin America, Africa and Asia (Keogh 2009). It has been planted and grown in more than 69 countries in the tropics and subtropics. Natural teak forests occur only in four countries of the world: India, Lao PDR, Myanmar and Thailand and covers an estimated area of 29.035 million ha, almost half of it growing in Myanmar. Myanmar is the only country supplying teak from natural forests to the international market. Global teak supply from natural and planted teak forests together contributes 2 to 2.5 million m3 which is roughly 2% of the total tropical round wood production. The supply of teak from natural forests are declining an alarming rate of about 1.3% globally and the planted teak shows an increasing trend from 1.3 to 5.7 million ha between 1995-2010 (Kollert and Cherubini, 2012). The total area of planted teak forests is estimated to be 4.346 million ha, of which 83% is represented by tropical Asia, 11% in Africa, 6% in tropical America and less than 1% in Oceania. Asia continues to hold more than 95% of the world’s natural and planted teak resources.
Production of high quality teakwood in relatively long rotations of 50-70-years has been the traditional practice ever since the first world's teak plantation was established in India (Nilambur- Kerala) in 1840s. Due to dwindling supply of teak from natural forests, teak logs from shorter rotations of 20-30 years appear promising and are being practiced for veneer and saw log production for relatively quick returns. Wood from short-rotation teak plantations, generally have a lower price in the timber market because the wood is considered inferior in its quality attributes such as: color, density, natural durability, and mechanical properties. Wood colour is an important deciding industrial feature for many uses like furniture and decorative veneers. Teak is well known to exhibit a wide geographic variation in wood figure. The Malabar teak (Nilambur, Kerala), generally having good growth and log dimensions with desirable figure (golden yellowish brown colour), has wide reputation in the world trade for ship-building. The recent studies indicated that short rotation teakwood coming from high rainfall areas of humid tropics have paler colour than that of teak harvested from areas of prolonged dry season (Bhat et al. 2005; Moya et al. 2012). Undoubtedly, wood figure of fast-grown teak in intensively managed plantations is likely to be different from that of traditional plantations and natural conditions. However, market will be standardized in future as the end-users will be aware of this difference and forced to learn to use the teak products of fast-grown plantations that will be the major source of high quality timber supply in the 21st century.
Logs from planted teak forests are typically smaller in size and they do not have the same technical characteristics of natural teak and do not fetch higher prices. The prices for teak logs and sawn timber are different in different countries, as no common log grading rules have been established and countries use several measuring units for log volumes and dimensions (e.g. diameter, girth, feet, board feet, hoppus tons, etc.). Adopting universal log grading rules and better pricing mechanism in teak trade in producer countries is required for better marketability of their products to receive equitable returns.
The natural durability of juvenile teak wood from high input plantations/farmlands and homesteads falls under the Class II of Resistant Timbers while mature wood generally belongs to the Class I of Highly Resistant Timbers as per ASTM (1981) standard. This is attributed to the lower extractive content of juvenile wood and its radial increase towards the outer heartwood region with age. The lower decay resistance of juvenile teak wood restricts its utilisation to some extent although it is still superior to many other moderately resistant or less resistant timbers of fast growing plantations like eucalypts. The hydrophobicity, antioxidant properties and oily nature of teak wood were mainly due to Caoutchouc compound (Simatupang et al. (1996). The study on 35-year old home-garden teak in India confirm that naphthoquinone is the single major compound which determines the decay resistance (Thulasidas and Bhat, 2007) and support the view of Haupt et al. (2003) that individual chemical composition, even if present in small amounts, is more vital than the total extractives in determining the durability of teak wood. Generally, mature teak from plantations displays wider variations in decay resistance than from the natural growth (Kokutse et al. 2005; Bailleres et al. 1997).
To achieve a high market value of teak wood particularly for dimensional sawn wood and decorative veneer, priority should be set in breeding for selection of traits among the important wood quality criteria which include: tree size, straight clear bole, figure (colour, grain and texture), dimensional stability, strength and natural durability. The specific breeding objectives should, therefore, include improvement of growth rate, straightness, height and girth of the tree as well as wood structure and properties that dictate the timber quality criteria. Wood specific gravity is considered as the best single indicator of wood quality owing to its relationships with various other wood properties and end use characteristics. According to recent studies, tree-to-tree variation appeared to offer more avenues for breeding than the variations between provenances in selecting denser timber with more uniform distribution of density from pith to bark regions keeping the structural end use of timber in mind. For clonal teak plantations, site is a more critical factor than the clonal origin for influencing the wood density. Assessment of wood properties, their correlation with morphological characteristics and changes as the tree gets older (Goh & Monteuuis, 2005), are needed to determine the best age for individual genetic selection. NIRS (Near Infrared spectroscopy) is an indirect method to estimate some wood properties of Teak as shrinkage (Baillères 2000; Kokutse et al. 2010). This tool will allow breeders for selection based on wood traits for Teak as well as for Eucalyptus, Pinus species. Adequate supply of genetically superior planting stock through micropropagated/clonal multiplication methods aiming at high yield with improved wood quality at shortest time is becoming a priority.
Advanced wood processing technologies allow the use of small and younger trees especially for finger-jointing and glulam structures. The recent results suggests that small and short rotation timber, though different, is not inferior as to reject it in the manufacture of high value products such as veneer, joinery, furniture, etc. The major challenge for plantation growers is to produce quality teak wood that is acceptable in international markets. The creation of uniform grading rules for plantation teak, along with standardized lumber and product grades would be of great help to improving the marketability of teak wood products. Research is needed in stand management to minimize fluting of teak trees which is a common occurrence in old teak stands and it occurs in younger plantations as well. Fluting reduces the utility of the lowest portion of the tree bole which has the largest diameter and greatest amount of heartwood. The recent research results on the production of heartwood/sapwood ratio of teakwood suggests that faster growth rates may be associated with greater heartwood content, contrary to the popular belief (Goh et al. 2007; Bhat, 2000). Increasing the early production of heartwood with reductions in sapwood content in younger plantations is critical for solid wood products. IUFRO has co-sponsored two International Teak Conference held in Peechi, India during 2003 and 2007. Teakwood Working Party with other teak institutions, viz. TEAKNET, TEAK21 together with the involvement of other R & D organisations and research partners of different countries, possibly under the umbrella of IUFRO, can initiate new collaborative ventures in the utilisation potential of planted teak.
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