Human Interactions Within Ecosystems (OCR Gateway GCSE Biology: Combined Science)

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Biology Project Lead

Humans & Ecosystems

Humans & ecosystems

  • Biotic factors are the ways in which the distribution of a species is affected by other species
  • By far the largest biotic factor on earth is the human impact on other species
  • Humans are the most intelligent and sophisticated species on Earth and have been biologically very successful
    • Humans have colonised all the continents
    • Humans have developed technology such as clothing, housing, hunting equipment, agricultural equipment etc to become the dominant species
  • Human success has come at a cost to other species, although there have been some notable positive interactions between humans and other species
  • Many interactions with humans have affected biodiversity
  • The largest factor in increasing human impact is the growing human population
    • Approaching 8 billion people (2022) versus approx. 2 billion a century ago
    • The population has doubled in the last 50 years!

Human population growth, IGCSE & GCSE Biology revision notes

Human population growth is growing exponentially

  • People nowadays expect a higher standard of living
    • A high standard of living requires more of the Earth's natural resources
      • e.g. oil, gas, rare earth minerals for electronic goods, red meat in the diet
  • Raw materials are being used up quicker and they can't be replaced
    • e.g. crude oil is running out, so alternatives need to be found
  • Waste materials build up and can create toxic effects in ecosystems
    • e.g. plastic build-up in the oceans

The Effects of Pollution

Sources of Water Pollution and their Effects Table

Sources of water pollution and their effects table 1, downloadable IGCSE & GCSE Biology revision notes

Bioaccumulation and biomagnification of a pesticide, downloadable IGCSE & GCSE Biology revision notes

Biomagnification and bioaccumulation of a pesticide in an aquatic ecosystem

Example of Human Impact on Ecosystems

Land use

  • Humans encroach onto more and more wild land for the following purposes
    • Farming
      • Often subsistence farming (producing just enough to supply their own family's needs)
      • To grow crops and host livestock
    • Quarrying or exploration for minerals and oil/gas
    • Building of homes and businesses
    • Waste disposal
    • Introduction on non-indigenous species

Increasing Human Land Use Table

Increasing human land use, downloadable IGCSE & GCSE Biology revision notes

Peat bogs

  • Bogs are areas of land that are waterlogged and acidic – plants living in bogs do not decay fully when they die due to a lack of oxygen
  • The partly decomposed plant matter accumulates over very long periods of time and forms peat
  • The carbon that would have been released into the atmosphere as carbon dioxide (if the plants had been able to fully decompose) is instead stored in the peat
  • Peat bogs are important habitats for many species (eg. migrating birds)
  • Destruction of peat bogs is happening because
    • Peat bogs are drained so that the area can be used for farming
    • Peat can be dried and used as a fuel
    • Peat can be used to produce compost for gardens or farms to increase food production

Negative impacts of peat bogs

  • Carbon dioxide is released into the atmosphere when peat is burned as a fuel – this contributes to climate change
  • Similarly to fossil fuels, peat bogs take so long to form that peat is effectively a non-renewable energy resource
  • The availability of peat bog habitat area for many species of animals, plants and microorganisms is decreasing, reducing biodiversity
  • Peat bogs are being destroyed faster than they can form – they are being used unsustainably

Positive human interaction with ecosystems

  • Not all human activity has caused damage to ecosystems
  • Humans have recognised that their planet's resources are finite, and have taken steps to reverse the downward trend in biodiversity
  • The future of the human species on Earth relies on us maintaining a good level of biodiversity
  • Just like any other species in an ecosystem, humans rely on many other species to survive (interdependence) 
  • For example:
    • We rely on photosynthetic organisms to produce oxygen, without which we cannot respire
    • We rely on pollinator species such as bees to pollinate our food crops
    • We rely on many plant species for medicine

  • Many human activities are reducing biodiversity and only recently have measures been taken to try to stop this reduction
  • Conservation is an excellent example


  • Conservation can help to protect biodiversity
  • It is not a way of preserving a habitat without any contact with humans
    • Conservation is more a way of allowing humans to use natural resources whilst living alongside other species, without harming biodiversity
  •  Conservation steps that can be taken
    • Habitats are protected
    • Harmful species are not allowed to be introduced
    • Protected areas like national parks and reserves are created
    • Safe areas like zoos and botanical gardens can be used as a bank of species to be conserved
  •  The following table lists some conservation examples that have had a positive impact on biodiversity

Methods of Conservation Table

Methods used to reduce our negative impact on ecosystems and protect biodiversity_1, downloadable IGCSE & GCSE Biology revision notes

Exam Tip

It is tempting to think of human impact being only negative, but for balance, make sure to mention examples of both positive and negative human interactions within ecosystems.

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Author: Phil

Phil has a BSc in Biochemistry from the University of Birmingham, followed by an MBA from Manchester Business School. He has 15 years of teaching and tutoring experience, teaching Biology in schools before becoming director of a growing tuition agency. He has also examined Biology for one of the leading UK exam boards. Phil has a particular passion for empowering students to overcome their fear of numbers in a scientific context.