Resistance to Decay of Fijian Timber — Osborne 
543 
for P. coccineus and 8 weeks for the other 
fungi. 
After completion of the main decay test, all 
blocks showing less than 10% weight loss after 
attack by C. olivacea or F. lividus were subjected 
to a further 16 weeks’ incubation with these 
two fungi. 
Measurement of Basic Density and Water 
Uptake 
It has been shown for 2 6 New Guinea timber 
species (Da Costa and Osborne, 1967) that 
there is a correlation between percentage weight 
loss and basic density and, more particularly, 
between percentage weight loss and water up- 
take. Therefore, measurements of these two 
properties were made on two specimens from 
each tree. The water uptake was measured by 
standing air-dry blocks, end grain down, in ]/g 
inch of water for 24 hours and calculating 
the increase in moisture content as a percentage 
of the oven-dry weight. The approximate basic 
density was calculated using the oven-dry 
weight and the "green” volume after blocks 
had been pressure-impregnated with water and 
allowed to swell for 48 hours. 
RESULTS 
The basic density and water uptake measure- 
ments, together with the decay figures, are 
presented in Table 2. As some timber species 
show considerable variation, both among trees 
and between the two radial positions within a 
tree, minimum and maximum values have been 
included, as well as the mean figure. As ex- 
pected, the outer heartwood was generally 
more resistant than was heartwood closer to 
the pith. In 70% of 41 6 relevant comparisons 
the percentage weight loss of the outer heart- 
wood was lower. 
Palaquium hornei proved extremely durable, 
being comparable in resistance with the very 
durable reference timber Eucalyptus microcorys. 
Intsia bijuga and Fagraea gracilipes also were 
durable, with several other timbers showing 
moderate durability. However, the remaining 
species showed poor resistance, most being 
highly susceptible. 
It can be seen from Table 2 that for each 
timber species there is a variation in the 
amount of decay depending on the particular 
test fungus, as well as a variation between 
trees. Because of these variations it is difficult 
to obtain a meaningful single-figure estimate 
of the relative decay resistance of the timber 
species. In Tables 2 and 3 the timber species 
are arranged in order of decreasing resistance 
based on the overall mean for the four fungi. 
However, other criteria may be used, such as 
the mean amount of decay caused by the most 
destructive fungus for each timber species, or 
the mean ranking for each timber (i.e., for 
each fungal species the timbers are ranked 1-30 
in order of percentage weight loss, and the 
mean of these rankings for the four comparisons 
is obtained). Mean ranking is useful in cases 
where the test fungi show different rates of 
decay, L. trabea in particular producing almost 
consistently lower decay losses than the other 
three fungi. The advantages and disadvantages 
of the various methods have been discussed by 
Da Costa and Osborne (1967). It can be seen, 
however, that no matter which criterion is used 
the general order of the timber species does 
not alter appreciably (Table 3). 
Results for the second decay test of the more 
durable species are shown in Table 4. Pala- 
quium hornei and Fagraea gracilipes still 
proved to be durable, whereas the remaining 
timbers showed quite appreciable weight losses, 
at least against the white-rot fungus F. lividus. 
An interesting result is that Intsia bijuga showed 
a great increase in weight loss after a further 
16 weeks’ incubation with F. lividus. 
As has been stated it was found, after testing 
had begun, that some timbers consisted of 
more than one botanical species (see Table 1). 
It is emphasized that these mixed groups in- 
clude only species which are regarded as being 
very similar in many respects, including natural 
durability. However, the following comments 
indicate the actual species tested. 
Of five trees tested of Calophyllum spp., 
three were identified as C. vitiense Turr. (mean 
percentage weight losses: 20.0, 15.7, 5.4) and 
two as C. leucocarpum A. C. Smith (weight 
losses: 20.4, 22.1%). The Canarium spp. group 
consisted of three trees of C. smithii Leenh., 
one tree of C. vitiense A. Gray, and one tree 
denoted as C. sp. aff. C. vitiense, all five trees 
