7.3 Biodiversity and human interaction on ecosystems

• What is biodiversity?


  The variety of different species of organisms on Earth or within an ecosystem
• What 3 things do different species depend on eachother for?

  Food, shelter, maintenance of physical environment
• How does a high biodiversity ensure the stability of ecosystems?

  By reducing the dependence of one species on another for food, shelter and maintenance of the physical environment
• Give 3 ways human activites are reducing biodiversity

  
  

  • Producing waste
  • destruction of habitats to make space for landfill and toxic chemicals from landfill waste can leach into soil
  • Deforestation
  • destruction of forest habitats that contain high biodiversity
  • Global warming
  • disruption of ecosystems and reduced biodiversity due to flooding of coastal habitats, coral bleaching, increased frequency of extreme weather events etc
• What does the future of human species on Earth rely on?

  Us maintaining a good level of biodiversity
• Give 3 ways humans relay on other species to survive

  • We rely on photosynthetic organisms to produce oxygen to respire
  • We rely on pollinators to pollinate our crops
  • We rely on plants for medicine
• Why have humans used increasingly more resources and produced more waste?

  • Rapid growth in the human population
  • Increase in the standard of living
• Give 3 examples of water pollutants

  • Toxic chemicals (pesticides and herbicides)
  • Untreated sewage
  • Fertilisers
• How do toxic chemicals in water affect biodiversity?

  • The chemicals cannot be broken down by organisms
  • They are absorbed by aquatic plants or invertebrates and can build up in the tissues of these organisms over time (bioaccumulation)
  • At each stage of the food chain, increasing levels of the chemicals build up in organisms, which can eventually build up to dangerously toxic levels in top predators, leading to death or failure to breed (biomagnification)
• How does untreated sewage affect biodiversity?

  • Sewage provides a good source of food for bacteria which increase rapidly, depleting the oxygen dissolved in the water as they respire anaerobically
  • Eutrophication - the lack of oxygen results in the death of aquatic organisms such as fish
• How do fertilisers affect biodiversity?

  • Fertilisers cause increased growth of algae and water plants
  • This results in algal bloom, which blocks sunlight so water plants on the bottom start to die
  • Algae also die when competition for nutrients becomes too intense
  • Dead plants and algae are a good source of food for bacteria, leading to eutrophication
• Give 2 examples of land pollutants

  • Toxic chemicals
  • Discarded rubbish
• How does discarded rubbish affect biodiversity?

  • Landfill sites take up a lot of room and their creation often results in the destruction of natural habitats
  • Toxic chemicals can spread from the waste into the soil
  • Much rubbish is non-biodegradable and remains in the environment for hundreds of years
• Give 2 examples of air pollutants

  
  

  • Smoke
  • Acidic gases
• How do sulphur dioxide and nitrogen oxides affect biodiversity?

  • Acid rain can damage plants and make rivers and lakes too acidic, resulting in the death of certain aquatic organisms
  • It can also cause the leaching of minerals that are toxic to fish, such as aluminium into lakes
• How does pollution reduce biodiversity?

  By killing animals and plants
• Give 4 ways humans have reduced the amount of land available for other animals and plants

  • Building
  • Quarrying
  • Farming
  • Dumping waste
• What are bogs?


  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
• What is peat?


  Partly decomposed plant matter which 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 could fully decompose) is stored as peat
• Give 3 reasons why peat bogs are being destroyed

  • They are drained so 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
• What are the effects of using peat?

  
  

  • Carbon dioxide is released in the atmosphere when peat is used as a fuel
  • This contributes to global warming
  • Peat bogs are a non-renewable energy source as they take so long to form, and they are being destroyed faster than they can form - they are being used unsustainably
  • Peat bogs are habitats for many species, so by destroying peat we are reducing biodiversity
• How can deforestation sometimes be sustainable?

  When the trees are replaced by replanting
• Give 2 main reasons for large-scale deforestation in tropical areas

  • To provide more land for farming
  • To grow crops from which ethanol-based biofuels can be produced
• Give 4 examples of undesirable effects of deforestation

  • Extinction of species
  • Loss of soil
  • Flooding
  • Increased carbon dioxide in the air
• Give some other reasons for deforestation

  • To provide land for farming
  • To provide land for quarrying
  • To provide wood for building materials
  • To provide paper
• What is a greenhouse gas?

  A gas that absorbs infrared radiation from the sun so it remains trapped in the Earth's atmosphere
• Give 5 examples of greenhouse gases

  • Water vapour
  • Carbon dioxide
  • Methane
  • Nitrous oxides
  • CFCs
• How have human activities increased carbon dioxide and methane?

  • Carbon dioxide is produced during the combustion of fossil fuel
  • Methane is produced by cattle as they digest grass and released by rice paddy fields
• Explain the greenhouse effect

  1. The sun emits rays that enter the Earth's atmosphere
  2. The heat bounces back from the Earth's surface and some heat is reflected back out into space
  3. Some heat is absorbed by greenhouse gases and is trapped within the Earth's atmosphere
• Explain the enhanced greenhouse effect

  Levels of greenhouse gases in the atmosphere rise due to human activities and the Earth's average temperature rises beyond normal (enhanced greenhouse effect) causes global dimming
• Give the consequences of global warming

  • Ocean temperatures rising - melting of polar ice caps
  • Increasing temperatures - extreme weather like flooding
  • Changes in or loss of habitats
  • Decreases in biodiversity
  • Increases in migration of species to new places
  • Includes increased spread of pests and disease
• How has evidence for global warming been developed?

  • There is scientific consensus (almost all scientists agree) that global warming is happening and that human activities are largely responsible for the most recent warming
  • This scientific consensus is based on systematic reviews of thousands of scientific research papers that have been 'peer reviewed' by other scientists
  • Although they can make good predictions, it is difficult for scientists to say for certain what the consequences of global warming will be
• Give 4 examples of negative human interactions with the ecosystems

  • Waste production
  • Peat bog destruction
  • Deforestation
  • Contributions to global warming
• Give 5 methods of reducing impact on ecosystems and protecting biodiversity

  • Breeding programmes for endangered species
  • Protection and regeneration of rare habitats
  • Reintroduction of field margins and hedgerows in agricultural areas where farmers grow only one type of crop
  • Reduction of deforestation and carbon dioxide emissions by some governments
  • Recycling resources rather than dumping waste in landfill
• What impact do breeding programmes have on biodiversity?

  • Breeding programmes have been set up to save endangered species from extinction
  • Endangered species are bred in captivity
  • Individuals can then be released back into their native habitats to help support or re-establish endangered wild populations
• What is the purpose of replanting hedgerows and field margins?

  There is higher biodiversity in the margins than the fields they surround
• What are some conflicting pressures on maintaining biodiversity?

  • The cost of programmes
  • Protecting food security
  • Land protected to maintain biodiversity could be used for farming, causing conflict in areas with food shortages
  • Development of society
  • Increasing amounts of land are required to sustain the increasing human population
• Why is peer review needed?

  • To detect for false claims
  • To make sure that research published in scientific journals is valid
• Reports in the popular media are not subject to peer review. What does this mean they can be?

  • Oversimplified
  • Inaccurate
  • Biased