776 president's address, 



lignite, but I do not see how this bears on the question referred 

 to. I may mention that rather extensive deposits of lignite occur 

 in alluvial deep leads (in old river beds) at Kiandra, Forest Reefs, 

 Molong, Grulgong, &c. I do not know whether you would 

 consider this as evidence of extensive forest destruction, and the 

 cause of these deposits, occurring as they do, in old river beds, is 

 not quite clear to me." 



I am aware that changes in the distribution of our forests have 

 probably more to do with climatic changes than volcanic or 

 alluvial action (of the kind indicated). For .example, we have 

 evidence that at the close of Tertiary times there was a much 

 greater rainfall than there is at the present time. The late Mr. 

 C. S. Wilkinson, in his Presidential Address delivered before this 

 Society in January, 1885, dealt ably with the subject, in regard 

 to which there is already a copious bibliography, but at present 

 I am alone concerned with the evidence, imperfect as it is, of the 

 changes owing to the forms of geological action I have indicated. 



iii. The ''Plains" of the Dorrigo ; a Plea for the Study 

 OF Physiographic Ecology. 



One phase of a botanical survey is the study of physiographic 

 ecology. The aims and scope of this quite modern subdivision of 

 botanical research are indicated, and a masterly summary of the 

 ramifications of ecology generally given by H. C. Cowles."^ 

 Warming, in his classical work, divides what he terms " plant 

 societies" into hydrophytes, mesophytes, and xerophytes, and 

 ecologists have largely developed Warming's ideas with an extent 

 of detail only possible because of the minuteness with which 

 botanical surveys have proceeded in older countries, or at all 

 events, because of the mass of data available. 



A. N. Whitford has a valuable paperf supplementary to that 

 of Cowles, whose pupil he is. He defines the factors to be taken 



* The Physiographic Ecology of Chicago and its vicinity; a Study of the 

 Orioin, Development and Classification of Plant Societies. Botanical Gazette, 

 February, 1901, pp. 73 et seq. 



t The Genetic Development of the Forests of Northern Michigan; a Study 

 in Physiographic Ecology. Botanical Gazette, xxxi. 281 (May, 1901). 



