biodiversity comparing-biodiversity-between-habitats

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Comparing Biodiversity Between Habitats

Once the abundance of different species in an area has been recorded, the results can be used to calculate the species diversity for that area
- Species diversity looks at the number of different species in an area but also the abundance across the different species
An index of diversity is a measurement that describes the relationship between the number of species present and how each species contributes to the total number of organisms that are present in that community

The index of diversity formula

The formula is:

$straight D space equals space fraction numerator straight N left parenthesis straight N minus 1 right parenthesis over denominator Σn left parenthesis straight n minus 1 right parenthesis end fraction$

Where:
- n = total no. of organisms for a single species in the community
- N = total no. of organisms in the community
- Σ = sum of
The larger the number obtained, the higher the level of diversity

Calculating the index of diversity

To calculate:
- Step 1: Calculate N(N-1) to find value A
- Step 2: Calculate n(n-1) for each species and add all these numbers together to find value B
- Step 3: Divide value A by value B

Worked Example

Samples of different insect species in a back garden were collected using sweep nets and identification keys. Use the data recorded to calculate the index of diversity.

The total number of organisms(N) in this community would be: 7 + 34 + 6 + 21 + 12 + 37 + 7 + 19 + 59 = 202

The formula is:

Answer:

Step one: Calculate N(N-1) to find value A

N(N-1) = 202(202-1)

N(N-1)= 202(201)

N(N-1) = 40602

Step two: Calculate n(n-1) for each species and add all of these numbers together to find value B

See table below

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Biology AS Edexcel Snab Revision

biodiversity comparing-biodiversity-between-habitats

Comparing Biodiversity Between Habitats

The index of diversity formula

Calculating the index of diversity

Worked Example

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