A1.1.2 Ecosystem


The term ecosystem is a contraction of the words ecological system. It is a way of thinking of all the components (both living and inanimate) of a geographically-defined environment as a single system.

An ecosystem can be as small as a pond or as large as a rainforest.

Groups of similar ecosystems are called biomes; for example, the Arctic Tundra is considered a biome. The world’s largest biome is the open sea.

Ecosystems are analysed and studied as unique entities. This study is a complex as the systems themselves. However, all ecosystems feature an energy input such as the sun’s heat which keeps life in the system going. Living organisms are classified into hierarchical food chains and webs and water, oxygen, carbon, nitrogen and phosphorous cycles are studied too.


Types of ecosystems

Ecosystems are most often classified by the type of vegetation that predominates and the climate area in which they are found. For example, tropical rain forests are classified as, ”tropical ombrophilous forests” according to the Unesco Vegetation Classification System, which is just one of the classification systems ecologists use.

Biomes (geographical areas of similar ecosystems) can be split into six types:

  • Freshwater
  • Marine
  • Desert,
  • Forest
  • Grassland
  • Tundra

These can be further divided.

Freshwater ecosystems are: ponds and lakes; streams and rivers and wetlands. Wetlands include bogs, swamps and marshes and contain the most species of any of the planet’s ecosystems.

Marine ecosystems are: oceans, coral reefs and estuaries. The oceans are the world’s largest ecosystems and are considered to cover the shore as far as tidal waters come in.

Desert ecosystems are: hot and dry deserts, semiarid, coastal and cold. While we often think of deserts and heats as synonymous, parts of the Arctic and Antarctic are classified as deserts because of their low rainfall.

Forest ecosystems are: tropical, temperate and boreal. Tropical forests include the great rainforests, which, with their incredible diversity of species and importance as carbon sinks are a focus for environmentalists. Boreal forests, also called taiga, are the largest biome on land.

Grasslands are: tropical (or savannas) and temperate. Temperate grasslands include the great American prairies and the Russian steppe.

Tundra ecosystems are: arctic and alpine.


WWF and National Geographic have classified the world into 867 ecoregions (essentially ecosystems) and you can find detailed profiles of them all on the WWF website: http://worldwildlife.org/science/wildfinder/ .