Communities and populations

There are a number of key terms within communities and populations:

  • an ecosystem is the interaction between a community of living organisms and their environment
  • the environment consists of all the conditions that surround any living organism - both the other living things and the non-living things or physical surroundings
  • a population is all the organisms of the same or closely-related species in an area
  • an ecosystem is two or more populations of organisms (usually many more) in their environment
  • a habitat is the place where an organism lives
  • a community is two or more populations of organisms
Oak tree environment. Root and litter zone has bacteria, earthworms, wood lice and funghi. Trunk has insects and larvae. Branches and leaves have bees, wasps, moths, squirrels, bluetits and hawks.A woodland ecosystem showing the habitats of different species.

Levels of organisation within an ecosystem

Organisms within an ecosystem are organised into levels.

ProducerProducers are plants and algae, which photosynthesise.
Primary consumerPrimary consumers are herbivores, which eat producers.
Secondary consumerSecondary consumers are carnivores, which eat primary consumers.
Tertiary consumerTertiary consumers are also carnivores. They eat secondary consumers.