17 
FOREST REGIONS IN AUSTRALIA. 
for indefinite periods of time a process of accommodation to diverse conditions of 
temperature, the result of which may be that a species is now very sensitive to 
cold in one part of its habitat and strongly frost-resistant in another. 
To understand the distribution of forest flora in Australia we must especially 
study the rainfall. The following figures based upon the normal rainfall values 
to the end of 1924 have been kindly supplied to the writer by H. A. Hunt, 
Commonwealth Meteorologist:— 
Area of Tasmania and Australia = 2,974,581 square miles. 
NORMAL RAINFALL VALUES TO END OF 1924. 
Under 
10 
inches 
per 
annum 
. 1,067,357 
square 
miles 
10 to 
15 
99 
55 • • 
. 603,605 
55 
55 
15 to 
20 
55 
55 * * 
. 358,458 
55 
55 
20 to 
25 
55 
99 
55 • * 
. 308,881 
55 
55 
25 to 
30 
99 
55 
55 • * 
. 225,885 
55 
55 
30 to 
40 
99 
99 
. 213,195 
55 
55 
Over 
40 
55 
99 
55 * * 
. 197,200 
55 
55 
2,974,581 
square 
miles 
FOREST REGIONS OF AUSTRALIA. 
In magnitude of the trees, and in density and purity of the forests the 
eucalypts attained their natural optimum in three climatically deliminated regions, 
as follows:—(1) Parts of Tasmania, mainly in the south and north-west; (2) An 
immense belt of country stretching from Bass Strait along the seaboard into South 
Australia and in the opposite direction over the eastern slopes and tablelands of 
Victoria, New South Wales, and Southern Queensland; (3) A similar but smaller 
region near the seaboard in south Western Australia. These regions all enjoy a 
reliable rainfall, the average amount of which varies according to locality from a 
little below 30 inches to 40, 50, and 60 inches per annum. Latitude and altitude 
together give these regions a range in mean annual temperature that may be 
stated in general terms as temperate to sub-tropical. 
Stretching southward, westward to near the coast, and far into the north on 
the mainland is a vast interior region. Its rainfall, from being about 25 inches 
per annum on the average along its margins, diminishes to 20 inches, 15 inches, 10 
inches, and less than 10 inches, as advance is made towards its climatic centre. Al 
travellers agree that the wealth and persistency of vegetation oyer most of this 
region is wonderful. The eucalypts are wide-spread in adapted forms, appearing 
in the south as stemless but abundantly branched mallees, on the grass lands as 
thinly distributed small trees and shrubs, and along the water-courses as larger 
specimens with wide-spreading tops. Drought-resistant acacias and other sma 
trees share the landscape with the eucalypts and in some parts wholly disp ace 
them. 
