NATURAL DECAY RESISTANCE OF KEMPAS (KOOMPASSIA MALACCENSIS) WITH INCLUDED PHLOEM AGAINST ROT FUNGI: A LABORATORY EVALUATION

Abstract

The natural decay resistance of tissues of included phloem, heartwood and sapwood of kempas (Koompassia malaccensis) was assessed by a modified ASTM soil-block test. The tissues were exposed to the rot fungi Chaetomium globosum (soft rot), Pycnoporus sanguineus (white rot) or Tyromyces palustris (brown rot). After six weeks' incubation, there was little decay of the included phloem (average mass loss: 0.7%), slightly for heartwood (3.7%) and considerably for sapwood (23.6%), irrespective of the fungi. The greatest and lowest mass losses were of the brown and soft rot type of decay, respectively. The superior natural durability of phloem tissues suggests that the decay resistance characteristics of kempas and related timbers with included phloem when used in contact with the ground should be reconsidered.