Ecosystem (Part-II)

Summary of Previous Lecture: In the previous lecture, we have discussed several aspects of ecosystem, various components of ecosystem and their relevance in maintaining ecology. Now in the current lecture, we will discuss, the relationship between different organisms and their role in the ecosystem.

CHARACTERISTICS OF FOOD CHAIN: The sequential inter-linking of organisms involving transfer of food energy from the producers, through a series of organisms with repeated eating and being eaten is referred as “food chain”. The biotic components of the ecosystem are linked to each other through food chain. In a typical food chain, producers are at the bottom and their role is to provide food for rest of the community utilizying solar energy (Figure 39.1). Other organisms belongs to the consumers and finally decomper are present at the bottom to recycle the organic content. In this manner, a nutritive interaction relationship exist between the living organisms of an ecosystem. It is always straight and always follow progressive straight line. The flow of energy is also unidirectional, from sun to producer and then different series of consumers. In a typical food chain, there are always 4 or 5 trophic level in the food chain. The distinct sequential steps in the straight food chains are referred as different trophic levels. For ex. Green plants stand at the first trophic level; the herbivorous are the second trophic level; and flesh eaters represent the third trophic levels. The position of plant is at the bottom but the position of other organism varies to different trophic level in different food chains. The typical representative food chains are given in the Table 39.1.

 

Figure 39.1: An Over-view of relationship between different organism in ecosystem.