The characteristics, properties and uses of plantation timbers - rubberwood and Acacia mangium

Rubber trees (Hevea bmsiliensix), which were introduced into Malaysia more than a century ago, have contributed tremendously to the social and economic well being of the country. Generally, the rubber trees start to decline in the latex production after 25 to 30 years of age. At 25 years, rubber trees normally have a clear bole of 3 to 10 m depending on the clones and the location of growth. The diameter of rubber trees could reach 50 cm at breast height. For logistic and ease of extraction, rubberwood logs are in short length of about 1.8 m. Rubber tree plantations (Figure 1) have a striking appearance in that the trees are mostly leaning and sometimes haphazardly in all possible directions giving rise to rather unbalanced crown structure, with few branches and bent in order to get to the maximum sunlight. The genetic, environmental conditions and the nature of growth are l ikely to cause the occurrences of tension wood and growth stresses, which in turn, affect the wood qual i ty , characteristics, utilisation and recovery. Acacia mangium, a species of the family Leguminosae, was first introduced into Sabah in 1967 as firebreak species. It was subsequently introduced into Peninsular Malaysia via the Compensatory Forest Plantation Programme (CFPP) in 1982. To date, a total of 51,768 ha of Acacia mangium had been planted in Peninsular Malaysia, mainly in the states of Johore, Negeri Sembilan, Pahang, and Selangor (Ho ct al. 1999). Acacia species normally demand full light for good development and may be stunted when grow in shade. Generally, Acacia trees are renowned for their robustness and adaptability, which makes them good plantation species. As Acacia mangium has a strong tendency to produce multiple leaders from the base, 's ingling' should be carried out during the early stage of growth. Regular pruning of branches is only necessary where the objective is to produce qual i ty saw or veneer logs (Arentz et al. 1995).