Biodiversity Revision Notes

Biodiversity, Species diversity index, the importance of diversity, the effects of farming and deforestation on biodiversity.

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  • Created on: 13-09-13 21:10
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Biology Unit 2- Biodiversity
Biodiversity depends on:
1. The amount of different species in an area.
2. The population size of each species in the area.
Species Diversity Index
The species diversity index (d) is a formula used to give a relative number of the diversity an area. It is used for comparison
between two areas, where a high species diversity index shows a more diverse population.
`N' is the total number of organisms in a habitat.
`n' is the total number of each species.
The Importance of Diversity
Areas with low species diversity are susceptible to mass destruction.
The bigger the species diversity the more secure the habitat.
Factors that can decrease diversity are:
Loss of food source.
New predators being introduced to an area.
Habitat loss.
Climate change.
Natural disasters, e.g. volcanoes, tsunamis.
The Effect of Farming on Biodiversity
Just one crop is grown over a very large area.
Bigger field mean that monocultures cover huge areas.
Farming lots of one type of animal.
This means there is a limit to the number of organisms that can survive because there is:
o A reduced number of types of food source.
o A reduced number of types of habitat.
Pesticides and herbicides-
Help to keep an area as a monoculture.
Prevent other organisms living in that area.
Not specific over which organisms they kill so greatly reduce the number of species in an area.
Reduced hedgerows-
Less hedges means more space.
Habitats and food sources are lost as a result of removing hedgerows.
Less habitats and food sources means there is reduced biodiversity in that area.
Farmers are paid to maintain hedgerows and field margins.
Wildlife corridors so that animals can move between fields and aren't isolated.
The Effect of Deforestation on Biodiversity
Less types of habitat.
Less types of food source.
Isolated pockets of forest (fragmentation) can lead to genetic bottlenecks which lead to a reduction in genetic diversity.

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