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Ecology

Ecology is the part of science that investigates the relationships between living creatures and how they depend on each other. It's impossible to understand environmental issues without some understanding of ecology.

The particular role a creature or plant takes in its region is called an ecological niche. Various factors affect whether the organism can keep its place. These include the availability of food and suitable breeding sites, and whether or not the creature can evade predators. Things do tend to balance out. For instance, if there are too many predators, the animals or plants they feed on will die out; but this will result in their being fewer predators over time, which will - other things being equal - allow the number of food animals or plants to rise again.

One of the most important relationships is, basically, 'who eats who'. This is called a food chain. An example of a food chain might be:

Grass->antelope->lion (with decomposers processing the dead bodies of both the antelope and the lion, and dead plant material).

However, in the real world things aren't quite so simple, and what actually happens is that there are many food chains which interlink. These make a food web.

Different organisms play different roles in the ecology - and sometimes more than one.
Green plants get their energy from the sun. They are eaten by - Herbivores - grazing and browsing animals - which are eaten by - Carnivores - meat eaters. Carnivores are at the top of the food chain. Nothing eats them, unless they die of natural causes or are killed by humans. Decomposers - live on the dead remains of plants and animals, breaking them down; they use some of the nutrients as food, but the rest returns to the environment. The most numerous of the decomposers are fungi and bacteria, but others include earthworms and beetles.

As you can see, harming one animal or plant in a food chain can have a profound effect on all the others.
Factors which can affect the organisms in a particular area include:

• Food supply
• Pollution
• Loss of breeding habitat
• Water supply
• Hunting
• Presence of human artifacts such as roads

Science in the National Curriculum

Helping With Science Homework

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