QUALITY OF PLANTATION-GROWN TEAK

It has been alleged that teak obtained from plantations is of inferior physical quality relative to teak obtained from the natural forest. More variability in wood quality has been observed in teak obtained from the natural forest than in plantation teak, and this is undesirable from the point of view of use. The general notion prevailing among teak users is that fast-growing teak produces only light, weak and spongy wood (Bryce, 1966).

However, studies conducted at the Forest Research Institute in Dehra Dun, India, do not support this view. Although plantation trees grow faster than forest trees, it has been shown that the relationship between growth rate and strength is not significant (Sekar, 1972).

Studies by Sanwo (1986) based on dominant, co-dominant and subdominant trees from a 27-year-old teak plantation in Nigeria showed that the rate of growth has no significant influence on specific gravity. Teak wood is generally stronger at the upper and lower ends and comparatively weak at intermediate heights. A study on 20-year-old teak trees grown in plantations in wet areas in India gave similar results (Kondas, 1995).

Other studies have indicated that wood density and mechanical properties are independent of growth rate or that fast-grown trees of ring-porous species have higher wood density and strength (Harris, 1981; Bhat, Bhat and Dhamodaran, 1987; Rajput, Shukla and Lai, 1991). More recently, a study on the wood properties of fast-grown plantation teak trees of different ages revealed that there were no significant differences in wood density, modulus of rupture (MOR), modulus of elasticity (MOE) or maximum crushing stress (Bhat, 1998). It was concluded that young trees (13 to 21 years of age) are not necessarily inferior in wood density and strength to older trees aged 55 and 65 years, and hence that the rotation age of fast-grown teak wood can be reduced without affecting the timber strength.

Various products such as glue-edged boards, furniture, doors and small teakwood artifacts have been made from thinning materials, showing that even sapwood can be used to produce high-quality objects.