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EVALUATION CRITERIA 



It would, of course, be ideal to know everything about a series of 

 areas. Weights could be given to various factors, areas compared and the 

 best areas selected with great precision. But even with the most carefully 

 studied forests or marshes, we have only begun to scratch the surface of 

 an immensely complicated ecology of plants and animals so interrelated with 

 each other and with the environment that ecologists hardly know where to 

 start unraveling. Because of the urgency of making an initial selection in 

 the shortest possible time, it was necessary to use secondhand sources 

 and information in the preliminary round of selection. The information was 

 grouped into ten categories which reflect the most immediately obvious 

 characteristics of each area. 



THE ECOSYSTEM 

 Ecosystems are rarely discrete with sharp edges allowing neat 

 demarcation. Usually there are gradients or ecotones where the species 

 characteristic of one habitat are gradually replaced by those of another. 

 Thus a salt marsh at its upper edge merges gradually with a fresh marsh 

 and the marsh in turn passes without break into the forest on its edge. 

 So in each area the dominant system was listed first with secondary systems 

 following if their role on the total site was an important aspect of that 

 site. Because of the ecotones between systems and the shifting dominence 

 of species in systems from site to site, the broad specturm of systems 

 recognized by many authoris has for convenience been reduced to eight 

 types. 



