Food Web - Ecosystem

A plant may serve as a food source for many herbivores simultaneously, e.g. grass plants can support deer, cow, grasshopper or rabbit. Similarly a herbivore may bc food source for many different carnivorous species. Also food availability and preferences of herbivores as well as carnivores may shift seasonally (e.g., we eat mangoes in the summer and oranges in the winter). In an ecosystem, when all interconnections between food chains are mapped out, they form a food web.

Figure:  A simplified version of a food web.

A food web illustrates, all possible transfers of energy and nutrients among the organisms in an ecosystem, whereas a food chain traces only one pathway in the food web. The food web for most communities is very complex, involving innumerable kids of living organisms. With many interlocking food chains the community remains stable even if one or more of these relations are altered. For example, in a stream-side ecosystem if the grasshoppers become scarce or their population is wiped out because of some calamity, the frogs preying on grasshoppers are not forced to die or move out of that place. They can instead feed on other organisms such as flies or butterflies. Obviously, then a food web introduces a strong element of stability into an ecosystem. Larger the number of components involved, the more stable the ecosystem is.