Factors Affecting Biodiversity

• Biodiversity


  Variety of life within and between organisms
• Factors affecting biodiversity


  • Human population growth
  • Habitat destruction
  • Overexploitation
  • Hunting
  • Agriculture
  • Climate change
• Human population growth


  • The global human population has been growing exponentially for the last 150 years
  • Improved technology leading to an abundance of food increase in birth rate
  • Improved medicine, hygiene and health care = decrease in death rate
• As the human population increases and countries become more economically developed

  Our requirement for natural resources also increases
• Increased requirement for natural resources


  Having a harmful effect on many aspects of the environment, including aquatic and terrestrial ecosystems, and our atmosphere and climate
• A conflict exists between human needs and the conservation of biodiversity
• Habitat destruction


  • Habitat loss (plant and animals completely lose their habitats)
  • Habitat fragmentation (habitats are divided into small areas - populations living within these separated habitat fragments are more likely to suffer from inbreeding or local extinction)
• Deforestation is one of the most damaging forms of habitat destruction, as forest habitats often have the highest levels of biodiversity
• Marine habitats are also being destroyed, including coral reefs and sea beds
• Overexploitation


  Natural resources are being used up faster than they can be replaced
• Overexploitation


  • Deforestation
  • Overfishing
• Hunting


  Removal of wild, non-farmed species of animals more quickly than their wild populations can be replenished
• Hunting


  • Hunting of animals for 'bush meat' in developing countries
• Agriculture


  • Farms became more specialised so they grew only one crop or raised one type of livestock (monoculture)
  • Switch to growing cereal crops rather than vegetables
  • Fields made bigger to accommodate machinery via the removal of hedgerows and stonewalls
  • More land made suitable by draining wetland and filling in ponds
  • Increased use of fertilisers and pesticides
• Most of these modern farming techniques have had a major negative impact on the level of biodiversity present in farmed areas
• Monocultures


  Support much lower levels of biodiversity compared to natural habitats or even natural grazing land
• Hedgerows represent an important habitat for many insects, small mammals and birds, which can nest there. As hedgerows are being increasingly removed, this habitat and the biodiversity it supports is lost
• Fertilisers can leach into waterways, causing eutrophication, which can lead to the death of many aquatic invertebrate and fish species
• Pesticides (e.g. insecticides) used on crops kill insect pests but also kill many non-target species, including important insect pollinators like bees
• Bumblebees


  Essential pollinators that pollinate wildflowers and valued crops such as oilseed rape and peas
• Almost a quarter of the European bumblebee species are threatened with extinction
• Bumblebees require habitats with a large number of flowering plants to ensure a supply of pollen and nectar all year round. Examples of this are hedgerows, field margins and grasslands
• The monoculture of crops

  Reduces plant diversity for bumblebee habitats
• Pesticides


  Can have a negative effect on bumblebees
• Farming practices that maintain or increase biodiversity can be expensive, labour intensive, time-intensive. They can also reduce the yield of crops and livestock
• It is difficult to find the balance between conservation and farming due to these knock-on effects
• Climate change


  • Human-caused climate change is causing weather patterns to change and the frequency of extreme weather events, such as hurricanes, typhoons, floods and droughts, to increase
  • Climate change is now occurring too fast for many species to be able to adapt to these changes, which could result in many species becoming extinct and a major decline in biodiversity
  • Global warming is causing many species to move towards the poles or to higher altitudes, which may lead to decreased biodiversity
• Increasing atmospheric CO2 is leading to more CO2 dissolving in seawater, decreasing its pH (known as ocean acidification). This is negatively affecting organisms that require calcium carbonate for shells (e.g. plankton and coral polyps)
• Increased ocean temperatures have also led to an increased frequency of coral-bleaching events, where the tiny organisms that live inside corals and help keep them alive leave due to temperature stress. Without these organisms, the corals die and are broken down, eventually leading to the loss of whole coral reefs and as a result, the loss of the huge amount of biodiversity that depends on them