ECOLOGY OF RAINFOREST AND SCLEROPHYLLOUS COMMUNITIES 
83 
modifying the topsoil chemistry. The dramatic 
topography and history of disturbance in this 
area seem to be more important than soil differ¬ 
ences in determining the distribution of vegeta¬ 
tion. 
Because of the importance of fire disturbance 
as a limiting environmental factor, the unburnt 
rainforest patches are best classified under the 
second of Webb & Tracey’s (1981) types of rain¬ 
forest refugia, as they are restricted to small, 
relatively dry and fireproof topographic niches. 
However, the disturbed rainforest along the 
river and shallow gullies can be construed as 
small, narrow gallery forests, falling under the 
third of Webb & Tracey’s (1981) refugia classifi¬ 
cations. Since many of the rainforest species 
occur at their climatic limits at the Mitchell 
River sites, the nature and frequency of disturb¬ 
ances play a particularly important role in deter¬ 
mining the extent and floristic composition of 
rainforest communities in these areas. 
The relative importance of the various ecolog¬ 
ical factors examined in this study are likely to 
apply to comparable mosaics of rainforest and 
sclerophyll forest occurring at the limits of dis¬ 
tribution for rainforest types. Although soil 
chemical properties are involved in the deline¬ 
ation of rainforest and sclerophyll communities 
in Queensland and New South Wales (Beadle 
1954,1962,1966, Webb 1968,1969), the impor¬ 
tance of edaphic factors is often diminished rela¬ 
tive to climate, topography and disturbance 
history, particularly in areas under less than 
ideal conditions (i.e. higher latitudes) (Mount 
1964, Tracey 1969, Webb 1969, Beadle 1981, 
Webb & Tracey 1981). Certainly, studies at 
some sites in East Gippsland (Melick 1988) indi¬ 
cate that natural disturbances and topography 
generally appear to be far more important than 
edaphic factors in determining the occurrence of 
rainforest and sclerophyll communities. 
ACKNOWLEDGEMENTS 
I thank Dr David Ashton for his support and 
advice throughout this study. Rangers Mark 
Doyle and Mick Cambell were always helpful 
and friendly, and Wayne Johnston assisted with 
some of the field work. Chris O’Brien provided 
photographic help and the Melbourne Univer¬ 
sity Surveying Department kindly plotted accu¬ 
rate contour maps of the study area, allowing the 
calculation of insolation data. I am also very 
grateful to Dr Bob Parsons for his useful com¬ 
ments on the manuscript. 
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