11) Biodiversity

• biodiversity:

  • the variety of living things found in an area
  • includes all living organisms
  • organisms are interconnected, they depend on each other
  • generally higher in areas near the equator (rainforests)
• importance of biodiversity:

  • maintaining the balance of the ecosystem
  • recycling and storage of nutrients
  • combatting pollution
  • stabilising climate
  • protecting water resources
  • forming and protecting soil
  • maintaining eco-balance
• main importance of biodiversity:

  • genetic variation
  • interdependence
• habitat diversity - refers to the number of different habitats within an area
• species diversity:

  species richness - the number of different species living within a particular area

  species evenness - a comparison of the number of individuals of each species within a community
• genetic diversity - the variety of genes that make up a species
• measuring biodiversity:

  • distribution
  • abundance
  • quadrats
  • transects
• measuring abundance:

  • percentage cover (quadrat)
  • abundance scale

  ACFOR scale: abundance, common, frequent, occasional & rare

  • species frequency
• non-random sampling:

  opportunistic - weakest form, uses organisms that are readily available

  stratified - population divided into subgroups. A sample of a subgroup is then taken to estimate its size

  systematic - can be done with line transects or belt transect
• Simpsons diversity index:

  D = 1-(Σ(n/N)²)

  n - number of individuals of a particular species

  N - total number of all individuals of all species

  the closer to 1 the higher the diversity