What is an ecosystem?
\nAn ecosystem is the living and non-living components of an environment and the interrelationships that exist between them.<\/p>\n
In any ecosystem, the living things interact with the environment and each other. For example, caterpillars in a wood breathe the air, feed on leaves, and get eaten by birds. If it
\ngets too cold, they die.<\/p>\n
Non-living components include the climate (temperature and rainfall), soil, water and light.<\/p>\n
Ecosystems can exist at different scales – a pond to tree to a hedgerow to the tropical rainforest or even the whole Earth.
\nHow do ecosystems work?
\nPicture
\nWe will use a small scale ecosystem such as a wood in the UK.<\/p>\n
All ecosystems work in the same way. Animals: A woodland ecosystem provides a habitat for a huge range of animals, such as squirrels, rabbits and deer – as well as insects and birds<\/p>\n
Plants: Vegetation grows in layers – with taller trees smaller trees and shrubs a herb layer of early flowering plants (such as bluebells) and a ground layer.<\/p>\n
Soil: The most common type of soil is brown earth<\/p>\n
Climate: Summers are warm, winters are cool<\/p>\n
Every ecosystem works in the same way; whether a small woodland to a large tropical rainforest<\/p>\n
The plants use sunlight, water and nutrient from the soil to produce their own food (so they’re called Producers)<\/p>\n
The animals feed on the plants, or each other (so they’re called consumers)<\/p>\n
Fungi and bacteria feed on dead and waste materials, and make things break down or rot (so they’re called decomposers) – they recycle nutrients for the plants to use again.<\/p>\n
Without plants all other things would die.
\nFood webs and food chains
\nPicture
\nIn any ecosystem, animals need to eat to survive – and whatever is eaten is part of the food chain. In the oak woodland, it works like this:<\/p>\n
oak leaf ————> caterpillar —————> wood mouse ————–> fox<\/p>\n
(The arrow means: ‘it gets eaten by’ and shows a flow of energy in the ecosystem)<\/p>\n
Often several consumers eat the same type of food. So, for example, caterpillars and aphids (a type of fly) both feed on oak leaves.
\nIndividual food chains then link up to form a food web.
\nEcosystem processes
\nPicture
\nRecycling nutrients
\n Nutrients continually circulate within ecosystems as the diagram to the left shows:<\/p>\n
Energy flows
\nEcosystems work because there’s a flow of energy through them. The main source of energy is sunlight, which is absorbed by plans and then
\nconverted by photosynthesis. Energy passes through the ecosystem in the food chain. Each link in the chain feeds on – and gets its energy from – the link before it<\/p>\n
Non-living environment ————-> Producers ————————> Consumers ——————> Consumers——————————-> Decomposers
\nSunlight is the main source of energy which Green plants convert by photosynthesis
\nHerbivores eat plants and obtain their energy from them
\nCarnivores eat herbivores,
\nOmnivores eat both<\/p>\n
Changes to ecosystems<\/p>\n
Different parts of an ecosystem depend on each other, and there’s a balance between them. A change in
\none part of an ecosystem will affect other parts and upset the balance. <\/p>\n
Ecosystems around the world are facing changes, or threats, including:
\nClimate change – which can affect where species can live, when the reproduce, and the size of their population
\nHabitat change – the conversion of land for farming can lead to a loss of habitat for huge numbers of species
\nPollution – which, for example, can reduce oxygen levels in wetlands and rivers (killing fish), and also cause rapid plant and algal growth (called algal blooms)<\/p>\n","protected":false},"excerpt":{"rendered":"