Biodiversity within a community

Biodiversity

Biodiversity refers to the variety of life and can be measured on different scales

It can relate to a small local habitat or to the entire earth

Species richness- the number of different species present in a community

Index of diversity- the relationship between the number of species in a community and the number of individuals in each species

Biodiversity can be used to

Describe a range of habitats from small local habitats to the entire earth

Low biodiversity might not be a concern e.g. expect this in the arctic or desert

A decrease in diversity is a cause of concern, and this is caused by human activity

Index of diversity

D = N(N-1) / n(n-1)

N = total number of organisms of all species

n = total number of organisms of particular species

D = simpsons diversity index

1 is the lowest value for D

The larger the value for D, the greater the species diversity

Farming reduces biodiversity- modern farming techniques are often designed to maximise food production but can reduce biodiversity. This is because they typically:

Remove habitats (e.g. through hedgerow removal or draining wetlands)

Use monocultures (large areas of a single crop)- which reduces species richness

Use pesticides and herbicides- which kill insects and unwanted plants, reducing food sources and habitats for other organisms

Overuse of fertilisers- which can lead to eutrophication and damage aquatic ecosystems