Biodiversity within a community

• Biodiversity

  The range and variety of genes, species and habitats within a particular region.
• Index of diversity

  Puts a figure to biodiversity for numerical comparisons.
• Species richness

  A measure of the number of different species in a community.
• Biodiversity accounts for:

  1. Species richness
  2. Species evenness- the relative abundance of each species.
• Index of diversity

  $d=$$\frac{N\left(N-1\right)}{\sum_{ }^{ }n\left(n-1\right)}$

  N= total no. of organisms of ALL species

  n= total no. of organisms of one species
• Uses of the index of diversity

  • Compare biodiversities of different ecosystems
  • Monitor change in biodiversity in a community over time
• Greater biodiversity= more healthy community
• How do farming techniques reduce biodiversity?

  1. Deforestation

  • Increases area for farmland
  • Reduces number of trees and tree species
  • Destroys habitats-> species die or migrate

  1. Removal of hedgerows

  • Increases size of fields, more efficient farming
  • Reduces number of trees and tree species
  • Destroys habitats- species die/migrate
• Use of herbicides and pesticides

  • Kills pests and weeds that would compete with the crops
  • Directly kills pests. Affects all organisms that feed on them as well (food chain affected)
  • Same for herbicides
• Monoculture

  • More efficient to grow just one crop
  • Reduces diversity
  • Can support fewer organisms as a habitat/food source as there are fewer niches
• Balance between biodiversity and farming

  • Reduce in biodiversity could affect food chains we rely on, as well as natural food chains
  • A less diverse ecosystem is more at risk of collapsing at an environmental change
  • Moral responsibility