52 
The South Australian Naturalist 
XV. The Flats Behind the Sandhills at Encounter Bay, at one 
time covered with bushes and semi-swamps, but now cleared 
and grass-covered but liable to flooding in very wet weather 
Probably with advantage still other subdivisions could be 
made. It is proposed, in this series, to supply notes on the plants 
of these various formations, though not necessarily takint^ them 
in the order of sequence just given. ° 
“SOME ASPECIT OF FORESTRY IN SOUTH AUSTRALIA’' 
Under this title Professor Sir Douglas Mawson delivered the 
Commemoration Address at the Adelaide University in December 
1925. The lecture has now been printed and may be obtained 
gratis on application at the University. 
Commemoration lectures are often abstruse and highly tech 
nical in character but there are exceptions, such as this, when 
the lecturer deals with a national question of vital importance 
to the future of the country. 
The lecturer stresses the importance of forest products as 
indispensable to human progress. Forests protect the soil of the 
hills from erosion and Sir Douglas stresses the importance of 
this in relation to our own hills. The economic position is also of 
immense importance. To quote from the lecture:— 
“Last year, according to the Statistical Register, South Aus- 
tralian imports of lumber and paper pulp products from Avithout 
the Commonwealth amounted to a wholesale value of approximate- 
ly £1,000,000. Importations from the other States and home pro- 
duction brings the total figure of South Australians dependance 
upon forest products to an amount probably not less than 
£1,500,000. When by-products, such as firewood, turpentine, res- 
in, honey, etc., are included, the figure is likely^ to be in the neieh- 
bourhood of £2,000,000. Such then is our dependance upon for- 
ests, and there is no obvious reason why at least a very large pro- 
j>ortion oi this requirement should not be produced in the State. 
Supply Forests for the State. 
The sine qua non of forest production is a sufficiency of 
water supply. Here in this State a twenty-inch rainfall is suffi- 
cient for certain useful timber growths, but for deliberate supply 
forests an annual precipitation of twenty-five inches is probably 
advantageous. 
Meteorological statistics show that within the State there 
the lowest desimble limit, and for pines thirty inches and upwards 
is an area of abouv. 829,000 acres within the thirty-inch rainlall 
belt. Of this some 50,000 acres are situated in the Adelaide Hiih 
and the remainder in the south-eastern districts. 
