Ecosystems and Biomes


An ecosystem is the living and non- living components of an environment and the interrelationships (connections) that exist between them.

The non living components within an ecosystem are called the abiotic components, examples of abiotic components are the climate (sun light, rainfall) and rocks. The living components are biotic, these include vegetation, animals and humans.

Ecosystems can be very big, or very small. Examples of small or local scale ecosystems are a hedgerow and a pond, large scale ecosystems include forests and lakes.

There are a number of important elements within the ecosystem that you need to know about…


Producers underpin the ecosystem. They get their energy from the sunlight and convert this into chemical energy that can be used by consumers. The most obvious producers are plants. Without the energy from the sun, and the conversion by the producers life in the ecosystem would cease to exist.


There are two types of consumers that you need to know about, herbivores, these are also known as primary consumers. Herbivores get their energy from eating the producers, normally plants or grass.  Carnivores, also known as secondary consumers feed on other animals.

Food chain

This shows the links between producers and consumers (linear – as a line)

Food web

This shows the links between producers and consumers in a more detailed way.

Scavengers and decomposers

Nature recycles everything, scavengers and decomposers enable it to do so. When plants and animals die scavengers and decomposers are responsible for transferring the nutrients from the dead plants or animals and back into the ecosystem. This is known as the nutrient cycle. Scavengers eat dead animals and plants while decomposers break down the remaining material returning it to the soil so it is now available for use again by the living plants and animals.


A biome is a large geographical area of distinctive plant and animal groups, which are adapted to that particular environment. The climate and geography of a region determines what type of biome can exist in that region. There are several biomes, you will focus on 3. Tropical rainforest, hot desert and deciduous woodland.

Tropical Rainforest Hot Desert Deciduous Forest
Location Tropical rainforests are located between the tropics and close to the equator. They are found down the wet eastern sides of continents including South America and South East Asia. Hot desert ecosystems are close to the tropics of Cancer and Capricorn (30°N and 30°S).  The largest area of desert is the Sahara in the African continent. Deciduous forests are located further north on the western sides of continents where winters are warmer than on the eastern sides. They form the natural vegetation cover for the UK.
Climate Hot all year round, average temperature of 27° to 30°C.Wet all year, annual precipitation of 2000-3000mm. Very hot in summer. Average temperatures of 35°- 45°C, dropping to around 20-30°C in the winter.  Deserts are dry all year with less than 250mm of precipitation. Warm summers with average temperatures of 16°-20°C. Mild/cool winters with average temperatures of 3°-8°C.Precipitation all year round, 550- 1500mm per year.
Soils Soils are surprisingly infertile. Most of the nutrients are found at the surface where dead leaves compose rapidly. The heavy rainfall quickly carries away nutrients. This is called leaching. It leaves behind an infertile soil called latosol. Soils are very dry and usually sandy or stony. They are not very fertile, but can soak up rainwater very quickly. Soils are rich and fertile; the soil found in this biome is brown earth.  Annual leaf fall provides plenty of organic material.
Vegetation adaptations
  • Drip tips on leaves help shed excess water and enable plants to cope with the exceptionally high rainfall.
  • Prop roots and buttresses help support plants in the shallow soil and because the roots do not grow very deep
  • Epiphytes are plants that live on the surface of other plant. They grow on trees to take advantages of the sunlight in the canopy, examples are orchids and ferns.
  • Plants have shallow roots to help capture nutrients from the top level of soil


  • Waxy coating on stems and leaves help reduce water loss
  • Long root systems (tap roots) spread out wide or go deep into the ground to absorb water
  • Leaves with hair help shade the plant, reducing water loss.
  • Some plants, called succulents, store water in their stems or leaves
  • In the autumn, trees drop their leaves to minimize water loss; they can also weigh the tree down if it snows.
  • Many trees have thick bark to protect against the cold winters
  • Wildflowers grow on the forest floor early in the spring before trees leaf out and shade the forest floor


Tropical rainforest and deciduous forests have a clear stratification of the vegetation, there are distinct layers. These layers are more pronounced in the tropical rainforest.

Emergent layer – The tallest trees are the emergents that tower above the forest at up to 200 feet. The emergent layer is made up of fast growing tress that out-compete each other to reach the sunlight. An example of an emergent is the capoc.

Canopy layer – This is the primary layer of the rainforest and forms a roof over the forest below. It is very dense and lush. Most animals live here as food and light are abundant.

Understory layer – The plants in this area are much shorter, reaching a maximum of around 12 feet. Little sunshine reaches here so the plants grow large leaves to catch any sunlight that reaches them.

Forest floor – It’s very dark on the forest floor, so dark that you might need a torch. Little vegetation grows here. Due to the humid conditions the recycling of nutrients happens extremely quickly. A leaf that might take a year to compose in other climates does so in 6 weeks in the tropical forest.

Watch below for an amazing clip showing plants trying to reach the light in the tropical forest

The living planet – Jungle