Food Webs: The Loss of One Animal Affects All Others Any change in the number and type of producers or consumers in a community can have dramatic consequences. Food webs show how organisms in an environment interact in more detail than food chains, which only show one line of energy flow. They help us understand the consequences of any natural or human changes to an ecosystem. A food web shows how all the organisms interact and from them we can see how the reduction in one animal or plant will effect all other organisms. A farmer finds that some of her sheep are being eaten by foxes. If we look at the food chain found on a farm it would seem that to have more sheep the farmer should reduce the number of foxes in the area. grass --> sheep --> fox But a look at the food web shows that the relationship between the animals found on and around the farm is much more complicated than the farmer first thought. If all foxes were killed it could lead to an increase in the number of pests like insects, mice and rabbits. As their numbers increase they eat more grass, reducing the food available for the sheep. The numbers of sheep would drop as they starved and lost condition due to the lack of food. By looking at the food web we can see that the presence of foxes in the ecosystem actually increases the productivity of the farm. It is better in the long term to loose a few sheep to fox attacks rather than reduce fox numbers and increase pests. Food webs provide valuable information on an environment and can help in the management and preservation of ecosystems.

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