[Editors' Note: Following the formal sessions of the Brookhaven symposium, a 

 small group of scientists met under the auspices of the Institute of Ecology to 

 consider three questions with respect to the world carbon cycle. The questions 

 were: 



1. What are the basic data on the carbon cycle? 



2. How is the carbon cycle altered by human activities? 



3. What research would best contribute to improved understanding of the 

 world carbon budget and its implications for man? 



Dr. William Reiners of Dartmouth College prepared a summary of these 

 discussions for the Institute of Ecology; it is reproduced here with permission of 

 the institute. — George M. Woodwell and Erene V. Pecan] 



APPENDIX 



A SUMMARY OF THE WORLD CARBON CYCLE AND 

 RECOMMENDATIONS FOR CRITICAL RESEARCH 



WILLIAM A. REINERS 



Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 



(in cooperation with participants of the Brookhaven Symposium in Biology No. 24)* 



THE CARBON CYCLE 



It is useful to conceive of the carbon cycle as a series of pools of carbon 

 interconnected by pathways of flux. The entire system ideally represents a 

 steady state that may adjust to new steady states with changes of geological 

 scale. The diagrammatic model of the carbon cycle in Fig. 1 is simpler than 

 others which are presented in this volume, but the model provides an adequate 

 format for the presentation of data. The carbon cycle is divided into four large 

 pools: the atmosphere, land surfaces, ocean waters, and sediments. Each of these 

 is, in turn, subdivided into constituent pools. 



In general, the larger the pool, the slower its rate of turnover. Whereas the 

 extent of control that one pool exerts over the cycle may increase with 

 increasing pool size (e.g., atmosphere, biota, oceans, and sediments), the 

 response time of these pools as buffering agents is approximately the inverse of 

 size. It appears that short-term and localized perturbations in carbon exchange 



*See page 381 for names of participants who contributed to this appendix. 



368 



