question. Two examples are E.P. Odum and H.T. Odum (1973) and Gosselink, E.P. 

 Odum, and Pope (1973). The Odums suggested that natural systems provide 

 "ecological life support" services for man and his economies and that the amount 

 of energy captured by the system in photosynthesis (gross primary production) 

 is a reasonable index of the magnitude of a system's life support function and, 

 therefore, its value. Gosselink, E.P. Odum, and Pope put a dollar value on 

 tidal marsh land by multiplying annual primary production (in this case, net 

 primary production), in energy terms, by the ratio of the Gross National Product 

 (GNP) to the National Energy Consumption Index (NECI). 



Determining economic value in terms of saleable products such as commercial 

 fish is a deceptively easy way to present ecosystem modeling results. It is 

 deceptive because it leads to an undervaluation; saleable products are not the 

 only products and services of ecosystems that are supportive of the society and 

 the economy. 



Various techniques have been used to put a dollar value on gross primary 

 production. The rationale is that gross primary production represents the 

 amount of energy from the sun being captured by the system. However, evaluation 

 on the basis of this rationale is not always appropriate. Furthermore, evaluation 

 on this basis alone must be incomplete because differences in gross primary 

 productivity do not reflect all environmental quality differences in an ecosystem 

 experiencing different types and levels of impacts. 



Our recommendations on the development of methodology concentrate on the 

 following: 



1. Identification of simulatable ecosystem properties and products that 

 can serve as useful environmental quality criteria. 



2. Categorization of these properties and products according to relevance 

 to the needs of various user groups or for their global utility (i.e., quality 

 of life). 



3. Quantification of these properties and products in terms of environmental 

 quality criteria. 



4. Translation of environmental quality criteria into terms of economic 

 value. 



While it is not the role of the ecosystem modeler to decide what user 

 groups to favor or what environmental quality criteria to optimize, ecosystem 

 modelers must be involved in the translation process. Conversely, the modelers 

 and research scientists must be informed by managers as to what objective 

 criteria are most important to them in making a decision. Scientific methods, 

 perhaps including sociological and demographic surveys, etc., may then be used 

 to connect in some rigorous way these two perspectives. 



VI. USE OF EXSTING DATA RESOURCES FOR ECOSYSTEM MODELING 



A voluminous amount of environmental and ecological data has been collected 

 over the past decades. The potential usefulness of these data to ecosystem 

 modelers, researchers, resource managers, and others is obvious. Unfortunately, 



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