1 6 THE STUDY OF PLANT COMMUNITIES • Chapter I 



The geographer's preoccupation with climatic causes for the 

 distribution of species was paralleled by another significant trend 

 of interest initiated by the writings of Grisebach in the nineteenth 

 century. He recognized groups of plants, or communities, as units 

 of study and described the vegetation of the earth on this basis. 111 

 This was the first step in the direction of modern studies of plant 

 communities. Although further expanded by the publications of 

 Drude, 94 the trend received its greatest impetus from the writings 

 of Warming, particularly his Oecology of Plants, 266 originally 

 published in Danish in 1895. This publication marks the beginning 

 of modern ecology as it is concerned with communities and the 

 interrelationships of organisms and environment. Although Warm- 

 ing must be credited with recognizing the complexity of these re- 

 lationships, he tended to place too much stress on water as a con- 

 trolling factor. In 1898, Schimper published his monumental Plant 

 Geography upon a Physiological Basis, which was later (1903) 

 translated into English from the German. Its author followed the 

 general plan of presentation begun by Warming but contributed 

 substantially from his broad experience and travels. He came near- 

 er to the modern interpretation of causes of distribution of vege- 

 tation by emphasizing the complexity of environment and the 

 interraction of factors. 



These, briefly, are the foundations of modern community studies 

 and the philosophy of modern ecology. From them stem studies 

 of the structure and classification of communities as emphasized 

 by continental European ecologists particularly, intensive studies 

 of habitat in the search for causes, and analysis and interpretation 

 of vegetational change as developed by American and English 

 workers. The history of modern ecology is so brief that the last 

 of these developments can hardly be treated historically. They are 

 the fundamentals of ecology today and, therefore, will be consid- 

 ered as part of the text material of this book. 



APPROACHES TO THE SUBJECT 



Considering the diversity of subject matter in ecology and the 



variety of possible interests, it is not surprising that problems have 



been studied in many different ways. Certain investigations must 



be made in the laboratory and others in the field. Some ecologists 



