546 
PACIFIC SCIENCE, Vol. XXI, October 1967 
60 
40 
20 
:• • 
POMES LIV1DUS 
• • 
• • 
• • 
J L 
20 30 40 50 
BASIC DENSITY (LB./ CU. FT.) 
60 
S 40 
20 
PYCNOPORUS COCCINEUS 
• • 
- 1 1 — * i - i» 
20 30 40 50 
BASIC DENSITY (LB^fcU. FT.) 
60 
40 
20 
LENZITES TRABEA 
• • • 
• * i • i •• 
l« 
20 30 40 50 
BASIC DENSITY (LB./CU.FT.) 
60 
40 
20 
CONIOPHORA OUVACEA 
• • 
% * 
J*. 
20 30 40 50 
BASIC DENSITY (IB./CU. FT.) 
Fig. 1. Relationship of decay resistance to basic density (species means). 
26 New Guinea timbers. The scatter diagrams 
in Figure 1, using species means, indicate an 
inverse correlation between basic density and 
percentage weight loss for each of the four test 
fungi. It may be argued that, even if absolute 
losses in weight are identical for blocks of 
different densities, there would be a spurious 
inverse correlation of density with percentage 
weight loss. This possibility has been tested 
statistically, and it has been shown that the 
absolute weight loss was not constant for all 
species, and that there was a small (r = 0.32) 
but highly significant correlation between den- 
sity and absolute weight loss. As with the New 
Guinea timbers previously tested, there was a 
tendency for the more water-absorbent species 
to be more susceptible to decay (Fig. 2). In- 
asmuch as there was also a correlation between 
basic density and water uptake, multiple re- 
gression analyses were made. These showed that 
for all four fungi, the percentage water uptake 
was a better predictor of percentage weight loss 
than was basic density, as is indicated from a 
comparison of Figures 1 and 2. The effect of 
water uptake was significant at the 5% level 
for F. lividus and L. trabea, and at the 1% 
level for P. coccineus and C. olivacea, whereas 
the additional effect of basic density was not 
significant for any of the fungi. 
The relationship between basic density and 
decay resistance also held within the timber 
species for all four fungi. Because it is not 
practicable to give detailed results, data are 
presented for four timber species which showed 
wide ranges of basic density (Fig. 3). Statis- 
tical analyses again showed that the correlations 
between absolute weight loss (and hence per- 
centage weight loss) and basic density were 
highly significant in each case. The detailed 
data suggested a similar correlation between 
