Biodiversity Flashcards
What is biodiversity?
Biodiversity is the variety of living organisms in an area.
What’s the difference between species richness and an index of diversity?
Species richness measures the number of different species in a community, whereas an index of diversity measures both the number of different species and the abundance of each species.
How does monoculture reduce biodiversity?
Monoculture is where farmers plant fields containing only one type of plant. This reduces the number of plant species in an area, which directly reduces biodiversity. A monoculture will also support fewer organisms, which further reduces biodiversity.
Explain how the use of pesticides and herbicides in agriculture can affect biodiversity.
Pesticides kill organisms that feed on crops. This reduces biodiversity directly by killing pest species. It may also lead to a reduction in the number of organisms that feed on the pests. Herbicides kill weeds. This reduces biodiversity by killing the weeds and reducing the number of organisms that feed on the weeds.
A green bridge is a type of wildlife crossing that animals can use to travel across a habitat that has been fragmented by human development. Suggest how green bridges could help to improve biodiversity.
E.g. species living in fragmented habitats may have limited access to resources (such as food) which could reduce their numbers. Re-linking parts of a fragmented habitat may allow organisms to migrate to more suitable areas, improving their chance of survival and so increasing biodiversity.
A study was conducted to investigate the impact on biodiversity of introducing a green bridge to reconnect a smaller habitat with a larger habitat.
Scientists counted members of different species of mammals present in the smaller habitat before and after the introduction of the green bridge.
Their results are shown in the table above. The index of diversity before the introduction was 1.98. Use the results and the formula below the table to calculate the index of diversity after the introduction of the green bridge. Give your answer to 2 d.p.
ii) What conclusions be drawn about how the green bridge has impacted biodiversity?
The index of diversity after the introduction of the green bridge is 2.44 (to 2 d.p.).
N(N-1) = 127(127 - 1) = 16 002.
Σn(n − 1) = 8(8 – 1) +11(11 – 1) +77(77 – 1) +22(22 – 1) + 9(9 – 1) = 6552.
So, N(N-1) [n(n-1)= 16 002 6552 = 2.442…
ii) The index of diversity is greater after the introduction of the green bridge. This suggests that the green bridge was effective at increasing the diversity of mammal species.
