778 president's address. 



(4) The zonal distribution of plants in swamps, as far as certain 

 localities in the United IStates are concerned, is given, and in 

 general terms it is shown how the mesophytic (hemlock-maple) 

 forest finally replaces the arbor-vitae or tamarack trees. 



The paper finally deals with the effects brought about by 

 human agency, the " clearing societies " brought into existence 

 through the agency of man and domestic animals. As in the 

 United States, so in New South Wales, there are but few useful 

 records of plant-succession in clearings. 



Little has been done in Australia in physiographical ecology. 

 I do not know that a systematic attempt has yet l3een made to 

 classify "plant societies" in this continent. Following are some 

 of them, but each group must be considered in regard to geological 

 and dynamical changes always in progress in any given area.* 

 No attempt is made to give a complete list; it is simply a sugges- 

 tion. 



Littoral Plants. 



Coast Sand-dunes. 



Western Sand-hills. 



Brackish and Mangrove Swamps. 



Brush Forests. 



" Plains" (Dorrigo and others). 



As an instance of the way in which the study of ecology may 

 be applied in a special case, let me bring under your notice 

 portions of the Northern Tableland, with especial reference to the 

 plains of the Dorrigo. I have briefly described these grass plains 

 and the brush lands,"}" and my two papers {loc. cit.) on this area 

 may be referred to. I feel that in the light of later experience 

 I ought to undertake another visit to endeavour to solve some 

 of the ecological problems I propose to bring under your notice, 

 and which are of more than local interest, but I should be very 

 glad if a young naturalist with fewer demands on his time than 

 I have would carefully explore it. 



* See p. 784. 

 t Agric. Gazette of N.S.W. v. 221. 



