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Topic last updated: 09 Nov 2023
    • Biology Biology
    • Ico Science Science
    • 14-16
    • 55

Ecosystems and ecology

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The impact of human activity on ecosystems


Biodiversity refers to the variety of all the different living species on Earth or within a particular ecosystem.

High biodiversity means that there are lots of difference species, and this is important for ecosystems due to species interdependence. The more species there are, the less dependent the ecosystem is on one species, which reduces competition and reliance.

Deforestation is a process in which humans cut down widespread areas of trees to use the land for farming or to use the trees for materials such as wood and paper. Deforestation is a good example of how humans are reducing biodiversity; before the trees are cut down, the forests contain many different species and have high biodiversity within an ecosystem. When deforestation occurs the whole ecosystem is wiped out, and biodiversity is reduced.


As the population rises and demand increases, humans are making more and more waste. The waste that we produce then contaminates water, the land and the air.

  • Water: In some countries sewage is released into water systems such as rivers and streams. Fertilisers may enter water systems too. When this happens the oxygen level in the water reduces (abiotic factor), meaning that animals and plants have less oxygen available and the population size decreases. This can reduce biodiversity. Toxic chemicals from factories entering water streams can have the same effect.
  • Land: Waste is placed into landfill meaning that the land is taken from living organisms. Pesticides and herbicides used for farming can kill animals too, reducing biodiversity.
  • Air: Burning fossil fuels adds greenhouse gases to the atmosphere and can pollute the air with pollutants. Some gases can cause acid rain too, such as sulfur dioxide. 

Land use:

As the human population and demand rises the need for land increases too. Humans mainly use land for farming (including cattle farming, crop farming and farming for biofuel biomass), as well as for buildings, for landfill and for quarrying to obtain metal ores. All of these uses of land destroy habitats and ecosystems, particularly peat bogs and forests which are destroyed for land use.