7-6 Energy flow diagram for a particular lake. Generalized 

 relationships of the average energy flow in the pelagic 

 zone of Dalnee Lake, Kamchatka, USSR, during the month 

 of July. Data expressed in calories per square meter 

 per 3(1 days (from Wetzel 1975; Sorokin and 

 Paveljeva 1972) 7-28 



7-7 Generalized pelagial plankton food web for a Maine lake 



(based on Davis et al. 1978a; and Wetzel 1975) 7-30 



7-8 Generalized food web for the littoral zone of a lake, 

 based on Cummins (1973), Pennak (1953), Wetzel (1975), 

 and R.B. Davis ( unpublished ) . Only certain species 

 of those taxonomic groups listed would be present 7-31 



9-2 Approximate distribution of major forest types in Maine . . . 9-7 



9-3 Patterns of primary and secondary succession under 



different substrate conditions along the coast of Maine . . . 9-9 



9-4 Generalized tropic structure of a forest system 

 showing major pathways of energy transfer (solid 

 lines are "grazing" pathways, broken lines are 

 "decomposer" pathways) 9-12 



9-5 Major storage compartments and flows of nutrients within 



the forest system (from Bormann and Likens 1979) 9-28 



xvi 



