Measuring Biodiversity

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Measuring Biodiversity

Biodiversity is split into:

1) Species richness: the number fo different species in a habitat; a qualitative measure

2) Species eveness: the relative abundance of individual species; a quantiative measure

Biodiversity is measured using the Simpsons Diversity Index.

This takes into account both species eveness and richness.

D = 1 - [  (n/N)  ]


Low number on Simpsons index --> sominated by a few speices --> a small change could effect one of these species and damage the whole habitat.

High number on Simpsons index --> more diverse habitat with many different species and organisms --> a small change in the habitat may effect one species which is a lower proportion of the total

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In Situ Conservation

In situ conservation means on site --> so protecting species in their natural habitat.

Important to ensure survival of endangered species - either at risk of extinction because of low population or a threatened habitat.

Can be done by:

  • Establishing protected areas e.g. nature reserves and national parks
  • Controlled introduction of a threatening species e.g. grey squirrels
  • Protecting habitats e.g. water levels
  • Restoring damages areas of habitat


  • (+) Often both species and habitat are conserved
  • (+) Large populations can be protected
  • Less disruptive than ex situ conservation and chances of population recovery greater than exsitu
  • (-) Can be difficult to control some factors
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Ex Situ Conservation

Ex situ conservation means off site, so removing part of a population from a threatened habitat and putting them in a new location (often a last resort).

Can be done by:

  • Relocating organism to a safer area
  • Breed organisms in captivity then reintroduce them to the wild
  • Botanical gardens are good controlled environments for plants
  • Seed banks - seeds frozen and stored without losing fertility


  • (+) Can be used to protect individual animals in a controlled environment e.g. predation and hunting are eliminated
  • (+) Used to reintroduce species which have left an area
  • (-) Few numbers can be cared for
  • (-) Difficult and expensive to produce the right environment
  • (-) Less successful than in situ conservation
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International Biodiversity Agreements

When deciding how to implement conservation methods, countries need to work together.

Rio Convention on Biodiversity:

Aims to develop international strategies on the conservation of biodiversity and how to use animal and plant resources in a sustainable way.

CITES Agreement:

An international agreement designed to increase international cooperation in regulating trade in wild animal and plant specimens.

All member countries made it illegal to kill endangered species.

Aimed to raise awareness of threats to biodiversity through education.

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Environmental Impact Assessment

An Environmental Impact Assessment is an assessment of the impact a development project might have on the environment.

It involves:

1) Estimating biodiversity at the site and evaluating how the development may affect it.

2) Identify ways biodivsity could be conserved.

3) Identify any threatened or endangered species on the site and any relevant laws.

4) Decide on any planning stipulations.

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