7) Models seldom incorporate changes in structure caused by either natural 

 variability, man-induced impact, or both. 



8) Mathematical characteristics of the commonly used procedures (parti- 

 cularly for nonlinear systems of equations) are not well documented. 



9) There is a definite lack of diversity of approaches to model formulation 

 and mathematics. 



10) Life histories of many critical species or species groups are not well 

 known and cannot be modeled adequately. 



Strong Aspects of Ecosystem Modeling 



1) Models are excellent organizers of ecological information. 



2) Models are a formal and objective vehicle for balancing differing 

 points of view. 



3) Models have the potential for answering the "what if" questions a priori . 



4) Models have the potential ability to focus research studies and field 

 efforts, the results of which can be used to upgrade model predictive 

 ability. 



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