man-induced interactions that take place, rendering 

 physiographic boundaries as logical limits for de- 

 lineating regional ecosystems. 



The coast of Maine north and cast of Cape 

 Elizabeth is considered a discrete physiographic' 

 ecosystem. The character of this area is quite dif- 

 ferent from that of southern Maine, New Hamp- 

 shire, and Massachusetts; it is identified by its long, 

 deep, steep shores and rock headlands. Large shal- 

 low cmbaymcnts are common and approximately 

 3,000 coastal islands ranging from less than 1 ha to 

 26,000 ha occur within 16 km (10 miles) of the 

 mainland. More areas of rock and silt and fewer sand 

 and salt marshes occur along the coastline of the 

 characterization aiea than in coastal areas to the 

 south. 



CLASSIFICATION MODEL 



THE ECOSYSTEM APPROACH 



In order to meaningfully describe the com- 

 ponents, functions, and interactions of the Maine 

 coast ecosystem, it will be necessary to impose 

 classification boundaries on those habitats having 

 relatively distinct functions. 



The U.S. Fish and Wildlife Service, Office of 

 Biological Services, has designed a National Classifi- 

 cation of Wetland and Deepwater Habitats of the 

 United States (Cowardin et al. 1977). The stiucture 

 of this classification system is hierarchical and 

 moves from systems and subsystems at the general 

 level down to classes and dominance types. 



The Maine State Planning Office (1974) has 

 developed a classification system for terrestrial 

 land cover. Among the features of these classifica- 

 tions is the ability to group ecologically similar 

 units. These classifications are, therefore, useful for 

 characterization and have been adapted to the 

 Maine coast study to structure and explain com- 

 ponents, functions, and interactions inherent in the 

 coastal Maine ecosystem. 



THE HABITATS 



Within the Maine coast ecosystem, three 

 generalized habitat types are recognized: deep- 

 water, wetland, and terrestrial. "Deepwater habi- 

 tats include environments where surface water is 

 permanent and often quite deep so that water, 

 rather than air, is the princip;d medium within 

 which the dominant organisms live, whether they 

 are attached to the substrate or not. Wetland is 

 land where water is the dominant factor determin- 



ing the nature (jf soil development and the types of 

 plant and animal communities living in the soil and 

 on its surface" (Cowardin et al., 1977). Terrestrial 

 habitats exist where water is not the dominant 

 influencing factor but where nonliydric soils exist. 

 These habitats are divided into systems, subsys- 

 tems, and classes. 



SYSTEMS 



"The teiTTi 'system' here refers to a complex of 

 wetland, deepwater and terrestrial habitats that 

 share the influence of hydrologic, geomorphologic, 

 chemical or biologic factors" (Cowardin et al. 

 1977). Each habitat thus comprises systems and 

 subsystems, so that a hierarchical conceptual 

 model is appropriate. 



We have thus far separated the Maine coast eco- 

 system into habitats, systems, subsystems, and 

 classes, each with certain distinct components and 

 functions which will be explained later. These 

 habitats, systems, subsystems, and classes interact 

 as part of a whole functioning ecosystem. Thus, 

 the ecosystem is emerging in the form of a gigan- 

 tic quasiorganism. The hierarchical structure and 

 general view of the composite systems in Maine are 

 presented in figure 2. Each habitat and composite 

 system is further illustrated in figures 3, 4, and 5. 

 A conceptual model has been developed that por- 

 trays this classification system's components, func- 

 tions, and interactons. 



THE CONCEPTUAL MODEL AND ITS APPLI- 

 CATIONS TO THE MAINE COAST ECOSYSTEM 



The general portrayal of the conceptual model 

 begins with the ecosystem and its driving forces, 

 which include climate, tides, geology, and socio- 

 economic factors interacting to form the template 

 with which the biotic realm must contend. In order 

 to illustrate the interactions within the ecosystem 

 (systems and classes) the discussion in the first 

 volume of this characterization focuses on four pri- 

 mary concepts: 



1. Energy— In ecology, we are concerned with 

 the manner in which sunlight is related to 

 ecological systems, and with the manner in 

 which energy is transformed within the 

 system (Odum 1971). Thus, the relation- 

 ships between producer plants and consu- 

 mer animals, and between predators and 

 prey are all limited and controlled by the 



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