knowt ap exam guide logo

How to use Shannon Biodiversity Index to Compared Biodiversity

The Shannon Biodiversity Index

  • A mathematical formula that measures the diversity of species in a community.

  • It measures the diversity of a community by considering both the species richness and evenness.

The Shannon Biodiversity Index Equation


With this equation, you’ll be solving for E! 

  • When E = 1, the species in a population are equally represented which means the population has biodiversity.


Variables to Know

  • Pi - represents the number of a certain species divided by the total population. 

    • The 'i' in Pi for this equation represents the species you are calculating Pi for.

  • S - represents the number of species in a population.

  • E - represents the evenness of species in a population. 

    • The fact that different species are represented evenly is an important factor of biodiversity.

  • H - represents the Shannon Biodiversity Index number. 

    • Higher values of H represent greater biodiversity.


Steps in Using the Equation

First Equation: How to get H

  1. Calculate Pi for each species

    • So if we had 18 snakes out of 110 total animals, it will be 18/110.

      • This would give us the answer .16

    • Every value of Pi added together should equal 1 or be close to it.

  2. Calculate the natural log (ln) of Pi for each value

    • Equation: In(Pi) 

    • With the snakes, the equation will be In(.16)

    • The answer -1.83 is our ln.

  3. Multiply each Pi to each natural log 

    • For the snakes, the equation will be 0.16 * 1.83

    • The answer will be -0.29 

  4. Add the Pi x ln values for each species

  5. Multiply the previous value by -1 to get the value of H

Second Equation: How do get E

  1. Plug in the value of H into the equation.


Using the Values to Compare

  • You’re able to use the E value to compare the evenness of different populations

    • The higher the E value, the more even the population.

  • You’re also able to utilize the H value for comparisons. 

    • The higher the H value, the greater diversity there is in a population.

SD

How to use Shannon Biodiversity Index to Compared Biodiversity

The Shannon Biodiversity Index

  • A mathematical formula that measures the diversity of species in a community.

  • It measures the diversity of a community by considering both the species richness and evenness.

The Shannon Biodiversity Index Equation


With this equation, you’ll be solving for E! 

  • When E = 1, the species in a population are equally represented which means the population has biodiversity.


Variables to Know

  • Pi - represents the number of a certain species divided by the total population. 

    • The 'i' in Pi for this equation represents the species you are calculating Pi for.

  • S - represents the number of species in a population.

  • E - represents the evenness of species in a population. 

    • The fact that different species are represented evenly is an important factor of biodiversity.

  • H - represents the Shannon Biodiversity Index number. 

    • Higher values of H represent greater biodiversity.


Steps in Using the Equation

First Equation: How to get H

  1. Calculate Pi for each species

    • So if we had 18 snakes out of 110 total animals, it will be 18/110.

      • This would give us the answer .16

    • Every value of Pi added together should equal 1 or be close to it.

  2. Calculate the natural log (ln) of Pi for each value

    • Equation: In(Pi) 

    • With the snakes, the equation will be In(.16)

    • The answer -1.83 is our ln.

  3. Multiply each Pi to each natural log 

    • For the snakes, the equation will be 0.16 * 1.83

    • The answer will be -0.29 

  4. Add the Pi x ln values for each species

  5. Multiply the previous value by -1 to get the value of H

Second Equation: How do get E

  1. Plug in the value of H into the equation.


Using the Values to Compare

  • You’re able to use the E value to compare the evenness of different populations

    • The higher the E value, the more even the population.

  • You’re also able to utilize the H value for comparisons. 

    • The higher the H value, the greater diversity there is in a population.

robot