S3d 



FACTORS WHICH INFLUENCE RANGE OR DISTRIBUTION. 



The following notes and abstracts deal with subjects which are more or less 

 inter-related : — 



1. Physiography — . 



Altitude Geocols, 



Aspect. 



2. Geology — 



Soils (including abstracts of Dr. H. I. Jensen's papers). 



1. Victoria. 4. Queensland. 



2. South Australia. 5. Northern Territory. 



3. New South Wales. 



3. Climate — 



Rainfall and, conversely. 

 Drought. 

 Note on species of apparently anomalous range. Meaning of Xerophily. 



[What follows are more or less disjointed notes on the genus, compiled, however, 

 by one who has undertaken wide reading and botanical travel. The student will, it 

 is expected, naturally turn to papers and more ambitious works which specially deal 

 with various aspects of Ecology.] 



INTRODUCTORY. 



Mr. R. H. Cambage, in his Presidential Address (Proc. Roy. Soc, N.S.W., XL VII, 

 18,1913) deals with the subject of factors in a comprehensive manner under the headings : 

 (l) Physiography, (2) Geology, (3) Climate. Under No. 1 Altitude and Aspect are 

 included ; under No. 2, Soils ; and under No. 3, Moisture, Temperature, and Wind 

 (shelter or exposure). He also deals with the geological side. 



At p. 21 he considers the effect of geological formations at some length, remarking 

 that there are two extreme types, the siliceous and the basic, and that the effect of these 

 soils is to some extent of a local nature, being dominated by the influence of climate. 

 Although certain trees show a distinct preference for either a basic or a siliceous 

 formation, it is difficult to ascertain the exact reason for this discrimination. The matter 

 of the mechanical condition of a soil is then discussed. 



At p. 22 he points out that the soils produced ftom similar geological formations, 

 in separate localities, have not always the same effect upon the local flora, the diversity 

 being caused by the differences in climate, rainfall and aspect ; but in areas where these 

 conditions remain the same, certain Eucalypts are typical of particular geological 

 formations. Examples in the Sydney district may be seen in the distinct preference 





