Biodiversity within a community

What is biodiversity?

● Variety of living organisms (species, genetic and ecosystem diversity)

● Can relate to a range of habitats, from a small local habitat to the Earth

What is a community?

All populations of different species that live in an area.

What is species richness?

A measure of the number of different species in a community

What does an index of diversity do?

Describes the relationship between:

1. The number of species in a community (species richness)

2. The number of individuals in each species (population size)

Suggest why index of diversity is more useful than species richness

● Also takes into account number of individuals in each species

● So takes into account that some species may be present in small or high numbers

What is the formula for index of diversity?

List the steps involved in calculating an index of diversity

Describe how index of diversity values can be interpreted

● High → many species present (high species richness) and species evenly represented

● Low → habitat dominated by one / a few species

Index of diversity: worked example

Explain how some farming techniques reduce biodiversity

Explain the balance between conservation and farming

● Conservation required to increase biodiversity

● But when implemented on farms, yields can be reduced, reducing profit / income for farmers

○ Eg. by reducing land area for crop growth, increasing competition, increasing pest population

● To offset loss, financial incentives / grants are offered

Give examples of how biodiversity can be increased in areas of agriculture

● Reintroduction of field margins and hedgerows (where farmers only grow one type of crop)

● Reduce use of pesticides

● Growing different crops in the same area (intercropping)

● Using crop rotation of nitrogen fixing crops instead of fertilisers

Exam insight: common mistakes ❌