Foreword 



This book is one of a series of volumes reporting results of research 

 by U.S. scientists participating in the International Biological Program 

 (IBP). As one of the fifty-eight nations taking part in the IBP during the 

 period of July 1967 to June 1974, the United States organized a number 

 of large, multidisciplinary studies pertinent to the central IBP theme of 

 "the biological basis of productivity and human welfare." 



These multidisciplinary studies (Integrated Research Programs) 

 directed toward an understanding of the structure and function of major 

 ecological or human systems have been a distinctive feature of the U.S. 

 participation in the IBP. Many of the detailed investigations that repre- 

 sent individual contributions to the overall objectives of each Integrated 

 Research Program have been published in the journal literature. The 

 main purpose of this series of books is to accpmplish a synthesis of the 

 many contributions for each principal program and thus answer the 

 larger questions pertinent to the structure and function of the major 

 systems that have been studied. 



Publications Committee: U.S. /IBP 

 Gabriel Lasker 

 Robert B. Piatt 

 Frederick E. Smith 

 W. Frank Blair, Chairman 



