ture; from field work on vegetation in desert scrub, grasslands, 

 forests, and tundra; from publications of the authors; and from 

 many years devoted to teaching courses in plant and general 

 ecology. The authors were inspired by men who have contributed 

 much to the development of ecology, including F. E. Clements, 

 J. E. Weaver, G. E. Nichols, V. E. Shelford, and C. C. Adams. 

 The authors are also greatly indebted to Jack Major, Warren 

 C. Whitman, R. H. Whittaker, Peter Gray, James B. Ross, and 

 Dorothy Donath for reading the manuscript and offering many 

 helpful suggestions, criticisms, and comments. 



Herbert C. Hanson 

 Ethan D. Churchill 



Washington, D.C. 



A rlington, Virgin la 



February, 1961 



Preface 



