Species richness & index of diversity

Sampling is an important technique for assessing biodiversity.

Sampling is used to measure the abundance of organisms in habitats.

State why sampling is necessary when measuring the abundance of organisms in a habitat.

Explain why it is important that sampling is random.

Quadrat sampling is a useful tool for measuring the abundance and distribution of plant species.

A student sampled plants on an area of sports field. Observations recorded by the student for two of the quadrats are shown in the image below. The symbols represent different plant species.

Quadrat A
Quadrat B

State the species richness in quadrat A.

Compare the species evenness in quadrats A and B.

Some students investigate the biodiversity of flying insect species in different parts of their school grounds.

The school has an area of wildflower meadow and some planted flower beds.

This is the method they use:

1. Select an area of wildflower meadow.

2. Pass a sweep net back and forward 5 times.

3. Shake the net into a tray and close with a transparent lid.

4. Use a key to identify the types of insect.

5. Release insects.

6. Repeat the procedure 9 times in different areas of the wildflower meadow.

7. On the same day, repeat steps 1 to 6 for the planted flower beds.

Their results for the wildflower meadow are shown in the table below.

Calculate the Simpson’s Index of Diversity for the wildflower meadow.

You may use the table above for working out.

Give your answer to 2 significant figures.

Explain the significance of the value for D calculated in part (i).

Describe how the students should select their sampling areas for steps 1 and 6.

Suggest two improvements that the students could make to step 2 of their method. For each improvement explain how that would increase the validity of the results.

Suggest and explain one limitation with step 7 of the students’ method.

Identify one problem with the way in which the students categorised their flying insect species that could reduce confidence in the calculated value for Simpson’s Index of Diversity.

The Convention on International Trade in Endangered Species (CITES) came into effect in 1975.

The kakapo, shown in Fig. 4.3, is an endangered species of flightless bird that lives in New Zealand. The population size of kakapos has experienced a large decrease over the past few hundred years. There are now fewer than 250 kakapos living in the wild.

State the term for a large decrease in population size that reduces the gene pool.

Adaptations can be categorised into three different types:

• anatomical

• behavioural

• physiological.

The table lists four traits that kakapos have evolved.

Complete the table by naming the type of adaptation represented by each of the four

The kakapo and two other species of bird, the kaka and the kea, evolved from a common ancestor approximately 70 million years ago.

The evolutionary timeline of the three species is shown in Fig. 4.4.

Fig. 4.4

Emergence of the Southern Alps mountain range

• The kakapo cannot fly. It forages for leaves and roots on the ground in forests and grasslands.

• The kaka can fly. It eats seeds, fruit, and occasionally the eggs of other birds in forest habitats.

• The kea can fly. It eats plants, larvae and other small animals. It lives in mountainous forest habitats.

• All three species live on the South Island of New Zealand and had overlapping ranges until the population size of kakapos started to decrease. Populations of kakas also live on the North Island of New Zealand.

A student studied the information and suggested that all three species evolved by sympatric speciation.

Evaluate the student’s conclusion.

New Zealand has a high species biodiversity compared to many countries.

Species biodiversity includes the concepts of species richness and species evenness.

Explain the difference between species richness and species evenness.

On a biology field trip, a student calculated that an area of ancient woodland had a Simpson’s Index of Diversity of 0.85.

Which interpretation of a Simpson’s Index of Diversity of 0.85 is correct?

A Biodiversity is high.

B Biodiversity is low.

C Interspecific variation is high.

D Intraspecific variation is low.

Your answer

The teacher said that this method would not allow the students to measure the distribution of plant species.

Suggest an improvement to the method that would allow the distribution of plants to be measured.

Identify a limitation with step 3 of the students’ method and explain why this limitation might affect the data collected.

The students’ results are shown in the table.

Calculate the Simpson’s Index of Diversity (D) for the students’ data.

The students found grass species difficult to distinguish from one another so they decided to record any grass species as ‘grass’.

Explain how the students’ decision might have affected the calculated value for D.

On a biology field trip, the same students surveyed a large area of heather moorland.

On this occasion they did not use quadrats.

Pairs of students were each assigned a large area of moorland. They rated the abundance of plant species using the following scale:

A = Abundant C = Common F = Frequent O = Occasional R = Rare

One reason the use of quadrats was inappropriate was that many moorland plants are too large to fit in the quadrat.

Suggest one other advantage of using an ACFOR rating scale for the students’ survey.

Suggest one limitation of using an ACFOR rating scale, instead of quadrat sampling, to rate the abundance of plant species.

Explain one way in which tourists can lead to an increase in the biodiversity of an area.

The Lake District contains large areas where timber is produced. One of the aims of the management of National Parks is to produce timber sustainably.

Using Fig. 18, estimate the percentage of land that is covered by woodland and forest.

Timber can be produced economically by a technique called clear felling. Clear felling can damage biodiversity.

Explain how it is possible to produce timber sustainably using clear felling.

Many schools visit the Lake District to undertake Biology fieldwork.

A group of students investigated the biodiversity of five herb plants they found in adjacent coppiced and mature areas of woodland in the spring of 2016.

Their results are shown in Table 18.

The students calculated the Simpson’s Index of Diversity (D) for the mature area to be 0.489.

Use the information in Table 18 to work out the Simpson’s Index of Diversity (D) for the area of coppiced woodland.

Use the example of the students’ fieldwork to explain how biodiversity can be considered at different levels.

Accurate analysis of an ecosystem’s biodiversity requires a detailed classification of organisms.

The spruce pine plant is given the binomial name Pinus glabra.

Place a tick (✓) in the box next to the species most closely related to Pinus glabra.

Explain why Pinus glabra and humans, Homo sapiens, are classified in the same domain but in different kingdoms.

A scientist sampled the species of trees present in two different habitats containing Pinus glabra.

The results of the sampling are shown in Table 5.

Using Simpson’s Index of Diversity, the scientist calculated the biodiversity (D) of Habitat A as 0.71.

Use the formula given to calculate the biodiversity of Habitat B.

Show your working.

State which habitat, A or B, has the greater biodiversity.

D ( Habitat A ) = 0.71

Habitat B was situated beside a lake and showed evidence of ecological succession.

The scientist planned to investigate how the biodiversity changed from the edge of the lake to the other side of habitat B.

State the collective name of the animal and plant populations that are present at the end of primary succession.

Suggest how the scientist could achieve the following during their investigation:

Sample all stages of succession in the habitat........

Minimise sampling bias........

Sample insect biodiversity........

The scientist also measured primary production in both the woodland and lake habitats.

Suggest the units the scientist should use to measure primary production in the two habitats.

Which of the statements, A to D, best defines the term species evenness ?

A the number of species in an area

B the relative abundance of each species in an area

C the relative number of individuals of a species in an area

D the spread of species over an area

Your answer