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American Museum of Natural History

If you are coming to the Museum on Saturday, May 25, please use one of the following entrances: 79th Street and Central Park West, subway entrance, or Weston Pavilion (Columbus Avenue entrance). The 81st Street entrance will be closed, but the Hayden Planetarium Space Show will be shown on a normal schedule.

How to Calculate a Biodiversity Index

The question of how many different species exist in a particular environment is central to the understanding of why it is important to promote and preserve species diversity. A uniform population of a single species of plants adapted to a particular environment is more at risk if environmental changes occur. A more diverse population consisting of many species of plants has a better chance of including individuals that might be able to adapt to changes in the environment.

Scientists use a formula called the biodiversity index to describe the amount of species diversity in a given area. A simple biodiversity index is calculated as follows:

the number of species in the area (numerator)
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the total number of individuals in the area (denominator )
= biodiversity index

For example, a 4 X 4 meter square area in a carrot patch has 300 carrot plants, all the same species. It has a very low biodiversity index of 1/300, or 0.003.

A 4 X 4 meter square area in the forest has 1 pine tree, 1 fern, 1 conifer tree, 1 moss, and 1 lichen, for a total of 5 different species and 5 individuals. The biodiversity index here is high, 5/5 = 1.

  • More About This Resource...

    • This brief online article show students how to use a formula called the biodiversity index to describe the amount of species diversity in a given area.

      • The article starts with an explanation of why an environment with a single species of adapted plants is more at risk.
      • Two sample calculations are given along with the formula, illustrating how the formula can be applied to a carrot patch or a forest area.

    • Teacher Tip

      Supplement a study of biodiversity with an activity drawn from this look at the biodiversity index.

      1. Ask students which area they think is at greater risk during environmental changes“an area with a single plant species or one with several dozen.
      2. Send students to this online article, or print copies of it for them to read.
      3. Have students identify several different nearby environments and calculate the biodiversity index for each one.

    • Topic

      Biology

    • Subtopic

      Tools and Methods