Human Interactions Within Ecosystems (OCR Gateway GCSE Biology)

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 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

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

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

• 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