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PREFACE TO THE GERMAN EDITION 



Phytosociology, the study of vegetation, has had a very rapid 

 development. A few years ago it lacked aim or limitations, appearing 

 merely as an offshoot of ecology, an appendix to geobotany. The 

 immediate past has wrought a great change. The rapidly accumulat- 

 ing mass of phytosociological data demanded arranging, testing, and 

 orienting in the system of sciences. It was further necessary to test 

 the findings of phytosociology philosophically, to reconsider its conclu- 

 sions, and to synthesize these into broad general principles. From 

 these exacting tests this new branch of science emerges with a well- 

 defined individuality. 



Meanwhile we have lacked any unified and comprehensive survey 

 of the scope, aims, and limits of plant sociology. The purpose of this 

 book is to meet this need and to supply a brief handbook to those who 

 are studying vegetation. 



This work, matured by many years of intimate contact with nature, 

 has grown out of my lectures at the Federal College of Technology 

 (Technischen Hochschule), Zurich, and out of ecological field trips in 

 Switzerland, Germany, and France. The leading principles and the 

 viewpoints are naturally those which I have persistently held for many 

 years — whether for better or for worse, time alone can tell. 



In the foreground of all my effort stands the plant community as a 

 social unit. Every natural aggregation of plants is the product of 

 definite conditions, present and past, and can exist only when these 

 conditions are fulfilled. The whole structure of plant sociology rests 

 upon this idea of sociological determination. Its definite objective, 

 however remote its accompUshment, is to catalogue and describe the 

 plant communities of the earth, to discover their causal explanation, 

 to study their development and geographic distribution, and to arrange 

 them according to a natural system of classification. 



In order to keep within the assigned limits of the book the text 

 has had to be severely restricted. The choice of suitable citations 

 from the voluminous literature required still greater restrictions. An 

 attempt has been made to include as far as possible the more important 

 contributions of North American, English, and Russian scholars. 



To all who have aided my work by counsel or by the loan of 

 photographs I extend my most cordial thanks. I am especially 



