Principal Steps and Components 467 



( 3 ) consumption of this material by consumers and its further elabora- 

 tion; (4) decomposition to inorganic compounds; and (5) transforma- 

 tion to forms suitable for the nutrition of the producers. If the area 

 is occupied by a self-sufficient community, all these steps will go on 

 within it; otherwise materials must enter from surrounding areas. 

 These steps in the operation of the ecosystem not only involve the 

 production, growth, and death of the living components but also may 

 influence the non-living aspects of the habitat. For example, con- 

 siderable energy is represented in the organization of the soil that is 

 brought about by the growth of the vegetation. 



The diagram in Fig. 13.1 illustrates the fundamental steps in a self- 



Essential components 



Non-essential components 



Light 



Nutrients 



Green plants 



Transformers 



Producers 



Carnivores 



> Consumers 



Non-living Living 



components components 



Fig. 13.1. Principal steps and components in a self-sufficient ecosystem. 



sufficient ecosystem and shows the nature of the components taking 

 part in the cycle of energy and material. The non-living components 

 that must be present are liglit energy and inorganic nutrients for the 

 growth of photosynthetic plants. The living components of the eco- 

 system consist of producers and consumers. The producers are repre- 

 sented primarily by green plants but also include synthetic bacteria. 

 The activity of the synthetic bacteria is of minor consequence in most 



