biodiversity and community

Question 1

1. What is species richness?

Answer 1

the number of different species in a community

Question 2

2. What does the index of diversity show?

Answer 2

The relationship between the number of species in a community and the number of individuals in each species.

Question 3

3. What is the difference between species richness and the index of diversity as a measure of biodiversity?

Answer 3

Species richness measures only number of different species, it does not measure number of individuals. Whereas index of diversity is a measure of both.

Question 4

4. What is the formula for calculating an index of diversity (d) and what do the symbols mean?

Answer 4

d=N(N-1) divided by Z n(n-1)

Question 5

5. How can a more precise index of diversity be obtained?

Answer 5

Take more samples and find mean; Select random samples using a grid and a random number generator for coordinates.

Question 6

6. Explain why the diversity (insects) is higher in a hedge/woodland than in a monoculture field.

Answer 6

More plant species; More food sources; More habitats / niches;

Question 7

7. Explain why the removal of hedgerows decreases the diversity of (birds)

Answer 7

Removes species of plant or insect; Fewer food sources; Fewer habitats or niches;

Question 8

8. What is the impact of farming on biodiversity?

Answer 8

Farmers need to maximise yields to make profit from their crops so fields are carefully controlled communities, with monoculture providing a very low index of diversity. Use of pesticides kills insects feeding on the crops reducing biodiversity. Removal of hedgerows to make way for large machinery reduces biodiversity. Use of fertilizer pollutes water (eutrophication) reducing biodiversity in ponds.

Question 9

9. Describe and explain the advantages and disadvantages of planting hedgerows to increase diversity on farmland.

Answer 9

Advantages: Greater biodiversity so increase in predators of pests so more yield due to less damage to crops; Increase in pollinators so more yield; May attract more tourists/subsidies to their farm so more income;
Disadvantages: Reduced land area for crop growth so less income; Greater biodiversity so increase pest population so less yield due to more damage to crops; Increased competition so less yield; More difficult to farm so less income;