CommunitiesSpec 4.7.1.1
An ecosystem is the interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment.
Levels of organisation
| Level | What it means | Pond example |
|---|---|---|
| Individual organism | One living thing | One frog |
| Population | All the organisms of one species living in the same area | All the frogs in the pond |
| Community | All the populations of the different species living in the same area | All the plants, animals and microorganisms in the pond |
| Ecosystem | The community together with the non-living parts of the environment | The pond community plus the water, light and temperature |
Tap to enlargeTo survive and reproduce, organisms need a supply of materials from their surroundings and from the other living organisms there.
Competition
Organisms in a community or habitat compete for the things they need when these are in short supply.
| Organisms | They often compete for |
|---|---|
| Plants | Light, space, water and mineral ions from the soil |
| Animals | Food, mates and territory |
Interdependence and stable communities
- Interdependence
- Within a community each species depends on other species for food, shelter, pollination, seed dispersal and so on. If one species is removed it can affect the whole community.
- Stable community
- A community where all the species and environmental factors are in balance so that population sizes remain fairly constant.
For example, if a plant species that is pollinated by one type of insect is removed, that insect loses its food, and the animals that eat the insect lose theirs. One change spreads through the community.