Human influences on ecosystems

• Intensive Food Production


  • Producing food more efficiently with a finite amount of land and other resources
• Ways modern technology has increased food supply

  1. Agricultural machinery has replaced humans and improved efficiency

  2. Chemical fertilisers improve yields

  3. Insecticides and herbicides kill pests and weeds

  4. Selective breeding of high-yielding animals and crops
• Intensive Livestock Farming

  • Keeping large numbers of livestock in a small area
  • Feeding high energy foods
  • Regularly giving medication
  • Keeping in artificially warm temperatures and small spaces
• Advantages of intensive livestock farming

  • Less land required
  • Food can be produced all year round
  • Lower cost of production
  • Lower labour requirement
• Disadvantages of intensive livestock farming

  • Use of herbicides and pesticides
  • Ethical issues with animal welfare
  • Habitat destruction
  • Reduction in biodiversity
  • Soil erosion
  • Methane production
• Monoculture


  Growing only one type of crop in an area
• Issues with monocultures

  • Lower biodiversity
  • Increase in pest populations
  • Overuse of pesticides
• Biodiversity


  The number of different species that live in a particular area
• Human activities have tended to force biodiversity downwards
• Reasons for habitat destruction

  • Increasing human population
  • Economic activities
  • Pollution
• Deforestation


  The clearing of trees, usually on a large scale
• Undesirable effects of deforestation

  • Extinction of species
  • Loss of soil
  • Flooding
  • Increase of carbon dioxide in the atmosphere
• Water pollution

  Pollution of land, water and air from various sources
• Eutrophication


  1. Runoff of fertiliser causes increased growth of algae and water plants

  2. Algal bloom blocks sunlight, causing plants to die

  3. Decomposing bacteria use up dissolved oxygen, killing aquatic organisms
• Plastic pollution


  • Non-biodegradability
  • Animals ingesting or getting caught in plastic
  • Toxins released as plastic breaks down
• Effects of plastic pollution on land

  • Toxins released into soil
  • Land unsuitable for growing crops or grazing
• Methane and carbon dioxide


  Greenhouse gases that contribute to global warming and climate change
• Plastic that has broken down into very small particles is commonly ingested by animals and enters the food chain
• Plastic disposal on land

  1. Burying in landfills

  2. As it breaks down, it releases toxins into the surrounding soil

  3. Land is no good for growing crops or grazing animals

  4. Can only be used for building on several decades after burial
• Both methane and carbon dioxide gases insulate the Earth and act as a 'blanket' around the atmosphere
• Higher levels of methane and carbon dioxide

  Have led to global warming and climate change
• Human activity has increased levels of both methane and carbon dioxide in the atmosphere
• Causes of increased methane and carbon dioxide


  1. Burning fossil fuels increases carbon dioxide

  2. Keeping livestock generates methane gas

  3. Global warming melts the permafrost in sub-polar regions, which results in even more trapped methane being released into the atmosphere
• Sustainable resource


  A resource that is produced as rapidly as it is removed from the environment so that it does not run out
• Non-renewable resource


  A resource, such as fossil fuels, that cannot be replaced once used
• Fossil fuels are being used as an energy source in increasing amounts, and are also the raw materials for many other products we make
• Some products, especially those made from paper, plastic, glass or metal, can be reused and recycled - this reduces waste in the environment and reduces the amounts of raw materials and energy needed to make new products
• Sustainable development

  Development providing for the needs of an increasing human population without harming the environment
• Balancing needs for sustainable development


  1. Balancing the needs of local people to utilise resources with the needs of large companies to make money from resources

  2. Balancing the needs of humans for resources with the needs of animals and plants that live in the areas the resources are taken from

  3. Balancing the needs of current populations with the needs of future populations
• For development to occur sustainably, people need to cooperate at local, national and international levels in the planning and management of resources
• Sustaining forests

  1. Replanting similar trees when mature trees are cut

  2. Introducing schemes to monitor logging companies and track the wood produced

  3. Education to ensure logging companies are aware of sustainable practices and consumers are aware of the importance of buying products made from sustainable sources
• Sustaining fish stocks

  1. Controlling the number of fish caught each year (quotas)

  2. Controlling the size of fish caught

  3. Controlling the time of year that certain fish can be caught

  4. Restocking (breeding and keeping offspring until they are large enough to survive in their natural habitat then releasing)
• Endangered species are at risk of becoming extinct due to reasons such as hunting, climate change, pollution, loss of habitat, and introduction of non-native species
• Conservation measures for endangered species

  1. Education programmes

  2. Captive breeding programmes

  3. Monitoring and legal protection of the species and of their habitats

  4. Seed banks as a conservation measure for plants
• There are moral, cultural and scientific reasons for conservation programmes, including reducing extinction rates, protecting food chains and food webs, protecting our future food supply and maintaining nutrient cycles and possible sources of future medical drugs and fuels
• Reasons for conservation

  • Maintaining or increasing biodiversity, which allows ecosystems to remain stable
  • Reducing extinction, which helps to retain iconic species and maintain biodiversity
  • Protecting vulnerable ecosystems which would have been quickly lost to human activity
  • Maintaining ecosystem functions such as nutrient cycling and resource provision
• Conservation techniques


  1. Artificial insemination (AI) in captive breeding programmes

  2. In vitro fertilisation (IVF) in captive breeding programmes
• If a species' population size decreases, it will experience reduced genetic variation, rendering the species more susceptible to environmental change and at greater risk of extinction