74 
E. A. CHESTERFIELD ET AL. 
nitens may resemble that of E. grandis Maiden, 
another eucalypt that associates with rainforest 
genera (Cremer 1960). The natural distribution 
of E. grandis is restricted to moist gullies or 
tablelands (Turnbull & Pryor 1978) due to its 
extreme sensitivity to fire (Pryor 1972). In the 
event of a change in fire regime to provide 
greater protection, the range of E . grandis may 
be readily extended into adjoining sites. Con¬ 
versely, an increase in the frequency and inten¬ 
sity of fire would cause a contraction of the 
range. Ashton (1981) considered that during the 
Pleistocene fires may have been much rarer 
events than at present, and that the wet sclero- 
phyll forests may have been relatively scarce 
ecotones between rainforests and the more 
drought resistant eucalypt forests or woodlands. 
As fire increased with increasing aridity during 
the early Quaternary, the contraction of rainfor¬ 
est may have enlarged the ecotone as fire re¬ 
duced or modified rainforest over the greater 
part of its range. Some species of Eucalyptus, 
Tristaniopsis and some rainforest genera ad¬ 
apted to regenerate following disturbance, or on 
marginal sites, e.g. Araucaria, Flindersia 
(Cromer & Pryor 1942), may have dominated 
this ecotone. The co-existence of eucalypts with 
cool temperate closed forest has been suggested 
in areas of Tasmania where fire is infrequent but 
sufficiently frequent (intervals less than 350 
years) to maintain the eucalypts (Gilbert 1959). 
Thus the fire regime during the early Quaternary 
may have contributed to vegetation with similar 
structure to the mixed forest surviving on Errin- 
undra Plateau, and in other isolated montane 
and coastal forests of southeastern Australia. 
After the arrival of the Aborigines, a sudden 
and dramatic increase in fire frequency may 
have allowed eucalypts to expand into moister 
sites that they had not formerly occupied (Smith 
& Guyer 1983). In southeastern Australia, 
species belonging to the subgenus Monocalyptus 
are frequently best adapted to such sites (Flor¬ 
ence 1981). Their more recent evolution on uni¬ 
form, regularly watered sites may explain a 
tendency to form monospecific stands in tall 
open-forests, lower tolerance to prolonged water 
stress and their restriction to higher rainfall 
zones in the south-east and south-west of the 
continent. The expansion of fire-adapted species 
may have seen a contraction of rainforest and 
mixed forest dominated by eucalypts adapted to 
long intervals between fires. The contraction 
would have occurred last in the most fire pro¬ 
tected localities. In some areas of Victoria, 
elevation and topography appears to have been 
important for the survival of E. nitens . 
At elevations below the limit of permanent 
winter snow, E. nitens is in competition with E. 
regnans and E. fasti gala and at higher elevations 
with E. delegatensis v In general, its competitors 
produce reliable, heavy seed crops and regener¬ 
ate prolifically after hot fires. In contrast, E. 
nitens produces light and irregular seed crops! 
and over a long period a series of hot fires could 
be expected to cause a progressive dimunitionin 
its abundance. In competition with E. regnans , a 
species of comparable vigour, the decline in £ 
nitens would be appreciable after each regener¬ 
ation phase. The ability of E. nitens to compete 
with E. delegatensis is limited by the dormancy 
characteristics of its seed. The stratification 
requirement of E. delegatensis seed indicates an 
adaptation to an environment where snow may 
lie for extended periods during winter (Boland et 
al. 1980). Without this adaptation, the mortality 
of E. nitens germinants would be high, re¬ 
stricting the upper limits of natural establish¬ 
ment to elevations where snow generally persists 
for less than several weeks. This environment 
coincides with the extremes in distribution for 
E. delegatensis and E. regnans , allowing E. 
nitens to exploit the ecotone where both its com¬ 
petitors are at the limits of their range. The 
occurrence of plateau land form at this vulner¬ 
able point in the elevation gradient of both £. 
regnans and E . delegatensis may have protected 
the niche available to£’. nitens by a modification 
of the fire regime. On plateaus, fires occur less 
intensely and probably less frequently, favour¬ 
ing the development of multi-aged stands. In 
forests with this structure, poor seed production 
would have been much less critical to species 
survival, and competitors promoted by fire less 
invasive. The fire regime occurring on plateaus 
also favours the development of rainforest un¬ 
derstories. An ability to co-exist at various times 
for extended periods in this association, may 
have been a factor in the survival of E. nitens on 
plateau and gully topography in Victoria. 
ACKNOWLEDGEMENTS 
We are indebted to Mr D. Sainsbury for the 
supply of the refrigeration units. Ms A. Lindsay, 
Geography and Environmental Science, Mon¬ 
ash University, kindly made a glasshouse avail¬ 
able for use in the trial. Constructive and valu¬ 
able comments on the manuscript were rnadeby 
Dr L. Pederick and Mr S. Cropper, Department 
