Variation in specific gravity and shrinkage of tapped rubberwood

Abstract

Hevea brasiliensis (rubber tree), a major source of natural rubber, could also be an important source of lumber as senescence occurs. However, latex collection is known to affect Hevea brasiliensis (rubber tree) wood formation and consequently, wood properties. The impact tapping (cutting made in the bark of the tree for latex harvest) has on the tree and the way the tree responds after tapping is often overlooked. Knowledge on wood properties of tapped rubber trees in Nigeria would enhance its sustainable utilization which is especially important in developing countries where lumber is limited. Variation in specific gravity and shrinkage of rubberwood wood due to tapping duration was examined. Tapping duration had significant effect in specific gravity and longitudinal shrinkage of rubberwood but had no effect on tangential and radial shrinkage. The specific gravity (SG) of rubberwood ranged from 0,55 - 0,59. Longitudinal shrinkage (average 1,42 %) was higher than typically observed for mature wood. Average tangential shrinkage for rubberwood of all the ages was 5,37 % while radial shrinkage ranged from 2,87 % to 3,84 %. decrease in SG observed in trees tapped for 20 years may indicate the initiation of senescence. Tapped rubberwood could be used in areas not exposed to high moisture as well as in other wood composites.