viii Preface 



The 1970 field program concentrated on initiating the field design 

 and establishing a series of field experiments and control plots. During 

 the summers of 1971, 1972 and 1973 a vast array of field data were gath- 

 ered from the Biome research area at Barrow. Summer 1974 was devoted 

 to initial synthesis in a summer-long workshop that formed the basis of 

 this volume, a companion aquatic volume (Hobbie 1980), and a volume 

 on primary producers (Tieszen 1978a). 



Several broad objectives guided the research design of the U.S. 

 Tundra Biome program from its inception: 1) to develop a predictive un- 

 derstanding of how the tundra system operates, particularly as exempli- 

 fied by the wet coastal tundra of northern Alaska; 2) to obtain the neces- 

 sary data base from a variety of cold-dominated ecosystems represented 

 in the United States so that their behavior could be modeled and simu- 

 lated and the results compared with similar studies underway in other cir- 

 cumpolar countries; and 3) to bring basic environmental knowledge to 

 bear on problems of degradation, maintenance, and restoration of the 

 temperature-sensitive and cold-dominated tundra and taiga ecosystems. 



The ecosystem approach and the use of ecological models were inte- 

 grating and research tools of the U.S. IBP Biome studies. Miller et al. 

 (1975) summarized the development of "box and arrow" representations 

 of the tundra ecosystem. Modeling in the U.S. Tundra Biome program 

 emphasized processes rather than the total ecosystem. This was done to 

 maximize the interactions among field observation, hypothesis formula- 

 tion, experimentation, and incorporation of results into working models. 

 Such models are regarded as necessary steps leading to the eventual de- 

 velopment of meaningful whole-ecosystem simulations. 



The ecological model is a research tool, not an objective. Because of 

 this, modeling cannot be separated from field experiments, and discus- 

 sions of the two are intertwined throughout much of the volume. Bunnell 

 (1973) emphasized the heuristic value of models that fail to predict accu- 

 rately or to mimic adequately the behavior of the real world. Such failure 

 indicates that either the model structure, certain parameter values, or the 

 basic hypotheses are incorrect, and thus contributes directly to our un- 

 derstanding. Many hypotheses and model structures have been tried and 

 modified or replaced as our understanding has developed. In this book 

 the models that incorporate our understanding as of the mid-1970's are 

 discussed and used to explore the behavior of organisms and processes 

 under a variety of conditions. In some cases, the predictions of models 

 have been subjected to testing, and results are presented. In other cases, 

 the evaluation of model behavior remains a topic for future research. 



Our intent has been to produce an integrated discussion of a tundra 

 ecosystem rather than a collection of independent papers on its compo- 

 nent parts. We hope that the reader will be motivated to read the book as 

 such. Books suffer from the constraint that they are necessarily unidi- 



