Themeda australis-Eucalyptus Savannah in Papua — Heyligers 
479 
The Trees 
DISTRIBUTION patterns (Fig. 2): Eucalyp- 
tus alba occurred over the whole transect 1 ; its 
height ranged from 9 to 16 m. On the black 
clay and adjacent texture-contrast soils it was 
accompanied or predominated by E. conferti- 
flora , of about the same height. Relative pro- 
portions of E. alba and E. confertiflora varied 
between 6:4 and 2:8. On the rest of the texture- 
contrast soils and the regosols E. alba was 
joined by E. papuana, varying in height be- 
tween 10 and 20 m and mostly remaining sub- 
ordinate. Relative proportions varied between 
9:1 and 5:5. Somewhere in the central part 
of the texture-contrast soils, over a distance of 
about 50 m, an overlap in the area of E. 
confertiflora and of E . papuana occurred (Fig. 
3). On the transition to the organic black clay 
soils some specimens of E. papuana also oc- 
curred. 
E. papuana occurred over the whole transect 
2, with heights ranging from 10 to 18 m on 
the flat country and from 17 to 22 m on the 
slopes and along the gully. E. alba, 9-13 m 
high, was concentrated on the texture-contrast 
soils, but some trees occurred along the gully 
and one single tree was growing on the slope. 
On the texture-contrast soils the relative pro- 
portions of E . alba and E. papuana varied be- 
tween 8:2 and 5:5. Not a single specimen of 
E. confertiflora was seen. 
The density is in the order of 150 trees per 
hectare. A more exact determination of density 
was abandoned because of signs of wartime dis- 
turbance such as local cutting of trees, trees 
that were pushed over, and patches of rather 
dense eucalypt regrowth. Moreover, it is un- 
likely that this would have contributed very 
much to an explanation of the described dis- 
tribution pattern. Observations of the 1962 
survey show that this rather haphazard pattern 
is a general feature. More detailed regional 
investigations may reveal the causal factors. 
root systems: Root systems were studied 
in 11 pits, which had been dug at the foot of 
the trunks, by removing as much soil from the 
roots as was possible without undue time- 
consuming effort. They usually appeared to 
consist of a small taproot and about five main 
horizontal roots branching from the base of the 
a 
PQ 
< 
H 
Data from Fitzpatrick (1965). 
* Data from monthly statistical summaries of Bureau of Meteorology, Melbourne (for the 8 months preceding this investigation). 
