Comparative Decay Resistance of Twenty-five Fijian Timber Species in 
Accelerated Laboratory Tests 
Lynette D. Osborne 1 
ABSTRACT: Specimens from the heartwood of 2-5 trees of each of 25 species of 
Fijian rain forest timbers were tested by the laboratory soil-block method against 
two white-rot fungi, Fomes lividus (Kalch.) Sacc. and Pycnoporus coccineus (Fr.) 
Bond, and Sing., syn. Coriolus sanguineus (L. ex Fr.) G. H. Cunn. ; and against 
two brown-rot fungi, Lenzites trabea Pers. ex Fr. and Coni op bora olivacea (Fr.) 
Karst. The species most resistant to decay were Palaquium hornei, Intsia bijuga, 
Fagraea gracilipes, Syzygium spp. complex, and Dacrydium elatum. Most of the 
species tested were highly susceptible to decay. 
There was a tendency, both among species and within species, for the denser 
and less water-absorbent wood to be more resistant to decay. Also, the outer heart- 
wood was, in general, more resistant to decay than inner heartwood. 
A recent study was made of the decay re- 
sistance of a number of tropical rain forest 
timbers of New Guinea (Da Costa and Os- 
borne, 1967). Prior to this there was almost 
no information on the durability of the rain 
forest species of New Guinea, or of the East 
Asian and South Pacific areas in general. Be- 
cause more and more local timber is now being 
used in these countries, there is an increasing 
need for knowledge of the approximate dura- 
bility of these timber species so that efficient 
use can be made of the timber available. This 
situation applies in Fiji, as local timber has not 
previously been used extensively for perma- 
nent structures, and little is known of its 
performance in service. Unfortunately, although 
both New Guinea and Fiji have tropical rain 
forest vegetation, it appears that there are very 
few species common to both countries, so that 
information obtained for New Guinea species 
has little application in the use of Fijian tim- 
bers. This fact is a reflection of the great vari- 
ety of tropical rain forest timbers in the world 
and emphasizes the need for information on 
the durability of this large group of timbers. 
It is therefore desirable to study the decay 
resistance of the species occurring most com- 
monly in Fiji so that suitable timber can be 
1 Division of Forest Products, CSIRO, South Mel- 
bourne, Australia. Manuscript received October 27, 
1966. 
selected for a particular use. For example, it is 
desirable to use the most durable timbers for 
conditions of high decay hazard, such as for 
transmission poles, fence posts, sleepers, and 
bridge timbers. Less durable timbers may be 
suitable for external joinery, etc., that is, not 
in ground contact, whereas highly susceptible 
ones would be unsuitable for any external use 
in the humid climate without preservative 
treatment. 
One method of obtaining this information 
is by graveyard stake tests, and a few species 
are being studied in Fiji in this way (Alston, 
1966). However, as these tests take some years 
to complete, an accelerated laboratory decay 
test was considered desirable. 
MATERIALS AND METHODS 
The methods used in this investigation fol- 
low closely those used in the study of 26 New 
Guinea timbers (Da Costa and Osborne, 1967) 
to which the reader is referred for more de- 
tailed information. 
Selection of Material 
The 25 Fijian timber species examined for 
decay resistance in these laboratory tests are 
listed in Table 1, together with local and 
family names. Although Swietenia macrophylla 
and Eucalyptus citriodora are not native to Fiji, 
539 
