PREFACE, 



The present book constitutes the general part of a monograph on 

 Rocky Mountain vegetation which has been under way since 1899. It 

 is hoped that another volume dealing with the details of the develop- 

 ment and structure of the cUmax formations of the Great Plains, Rocky 

 Mountains, and Great Basin may appear subsequently. The general 

 principles advanced here are an outgrowth of the treatment in the 

 "Development and Structure of Vegetation" (1904) and "Research 

 Methods in Ecology" (1905), in which an endeavor to organize the 

 whole field of present-day succession was made for the first time. The 

 studies of the past decade have confirmed and broadened the original 

 concepts, and have led irresistibly to the conclusion that they are of 

 universal application. The summer of 1913 and the spring and sum- 

 mer of 1914 were spent in testing both principles and processes through- 

 out the vegetation of the western half of the continent. The area 

 scrutinized extends from the Great Plains to the Pacific Coast and 

 from the Canadian Rockies to the Mexican boundary. The great 

 climax formations of this region were traversed repeatedly, and their 

 development and relations subjected to critical analysis and comparison. 



As a consequence, it is felt that the earlier concept of the formation 

 as a complex organism with a characteristic development and structure 

 in harmony with a particular habitat is not only fully justified, but 

 that it also represents the only complete and adequate view of vegeta- 

 tion. This concept has been broadened and definitized by the recogni- 

 tion of the developmental unity of the habitat. As a result, formation 

 and habitat are regarded as the two inseparable phases of a develop- 

 ment which terminates in a climax controlled by climate. Hence, the 

 basic climax community is taken to be the formation, which exhibits 

 serai or developmental stages as well as climax units. It is hardly 

 necessary to point out that this places the study of vegetation upon a 

 purely developmental basis, which is as objective as it is definite. 



The recognition of development as the cause and explanation of all 

 existing climax formations forced the conclusion that all vegetation 

 has been developmentally related; in short, that every climax forma- 

 tion has its phylogeny as well as its ontogeny. This led at once to the 

 further assumption that the processes or functions of vegetation to-day 

 must have been essentially those of the geological past, and that the 

 successional principles and processes seen in existing seres hold equally 

 well for the analysis of each eosere. As a consequence, it has been 

 possible to sketch in bold outline the succession of plant populations in 

 the various eras and periods, and to organize in tentative fashion the 

 new field of paleo-ecology. 



