Natural durability of some commercial timbers of Sarawak, Malaysia in tropical marine environment
K Jenang, Wang Choon Ling
The abundant supply of timber resources in Sarawak makes timber an ideal choice to be used for marine construction. The natural durability of the main commercial timber species of Sarawak in ground contact is well established but the same is not available for marine environment.
This study was conducted to assess the natural durability of 28 commercial timber species in tropical marine environment.
Timber specimens measuring 30mm x 100mm x 300mm each suspended in metal cages were exposed at two sites to marine borer attack for a period of 12 years. Durability was assessed at six-monthly interval. The borer species found at the test sites were identified including one new borer species encountered. In addition, water quality parameters encompassing current speed, temperature, dissolved oxygen, salinity, turbidity and pH were monitored during the period.
The results show that none of the species was durable with mean durability ranging from <0.5 – 3.0 years. Even Belian (Eusideroxylon zwageri) dubbed as the “iron wood of Borneo” and being the most durable timber species in Sarawak especially in ground contact and siliceous timber such as Kembang semangkok (Scaphium macropodum) has a mean durability of 3.0 and 1.2 years in marine environment, respectively. The majority of the species failed within six months. The specimens were destroyed by a combined action of teredine borers and pholad.
Keywords: Natural durability, timber species of Sarawak, marine environment, marine borers