Lesson 2

Question 1

To assess biodiversity of a habitat or geographical area you need to determine…

Answer 1

The number of different species present in the area
The number of individuals of each species present in the area

Question 2

Random sampling
- every individual organism / species must have an equal chance of being included in the sample
- the sampling method ensures that the sample is representative of the whole population of each species.

Why?

Answer 2

Reduces subjectivity and removes bias from the data collected

Question 3

What can quadrats be used for

Answer 3

Quadrats can be used to collect data on population sizes for organisms that do not move or move slowly.
Quadrats are frames of a known area e.g., 0.25m2 or 1m2.

Question 4

How do you chose the size of the quadrats?

Answer 4

The choice of size of quadrat depends on the area being sampled and the size of the organisms:
- small quadrat: a narrow area or an area with a high level of diversity
- large quadrat: counting trees in a wood (may need 10 x 10m2quadrats).

Question 5

What are reasons to use random sampling?

Answer 5

• To ensure the data is respresentative
• To avoid bias

Question 6

The area to be sampled is divided into a grid pattern with what?

Answer 6

Indexed coordinates

Question 7

How are coordinated selected?

Answer 7

At random, using dice or random number generator

Question 8

What is recorded at each quadrat?

Answer 8

Numbers/frequency/percentage cover of each species in each quadrat

Question 9

What are the different ways of counting species and individuals?

Answer 9

• species density
• species frequency
• species cover

Question 10

What is species density?

Answer 10

Number of individuals of a given species in a given area. Calculated as mean number per quadrat converted to a mean number per m2 multiplied by the area of the habitat

Question 11

What is species frequency

Answer 11

It is a measure of the probability of finding a given species with any one placement of a quadrat in a given area. Species frequency is found by recording the presence or absence of a species in a quadrat.

Question 12

If a species occurs once in every 10 quadrats, what is its frequency?

Answer 12

10%

Question 13

Species frequency is a quick and easy method of assessing ________, but the values depend on ___________ and____________.

Answer 13

Species frequency is a quick and easy method of assessing biodiversity, but the values depend on the size of the quadrats and values depend on the spatial distribution of the organisms.

Question 14

Organisms found in clumps may have a _____ density but a ____ frequency. e.g. _________.

Answer 14

Organisms found in clumps may have a high density but a low frequency. e.g. many plants growing in only a few places

Question 15

What is species cover?

Answer 15

It is a measure of the proportion of ground occupied by a given species. This is a useful technique when studying plants that spread over the ground and it is difficult to identify individuals. Estimate how many squares in the grid are covered by the plant and convert to a %.

Question 16

What is the ACFOR scale?

Answer 16

This is an estimate of abundance,
A = abundant
C = common
F = Frequent
O = occasional
R = rare.
This is only semi-quantitative and is subjective.

Question 17

What is preliminary work

Answer 17

Preliminary work is usually required to determine the minimum number of quadrats that need to be used to ensure that all species living in a habitat are sampled.

This involves placing quadrats randomly and recording the cumulative number of species. When there is no further increase in the number of species recorded in the habitat, this indicates the minimum number of quadrats to use.

Question 18

Explain a transect

Answer 18

A transect is a line that runs across the habitat being studied with different values of an environmental factor along the line. This is used to study how an environmental factor that changes across a habitat affects the abundance and distribution of organisms.

To increase the repeatability of your data and increase your confidence in any conclusions reached, you would need to repeat the study at several points across the same study area.

There are different transects that you can use depending on the subject of the research or the environment or scale etc

Question 19

What are the different methods of transect?

Answer 19

Line transects, belt transects and kite diagrams

Question 20

Explain the line transect method

Answer 20

• run a line across the area being studied and then at evenly spaced points (e.g. every 1 or 2m), you identify the species of organism touching the transect.

-This is a good method for a long distance.

• This method only provides information on presence of a species. No information is collected on abundance at different distances along the transect.

Question 21

How would you use the line transect to describe difference in plants in a woods?

Answer 21

To describe the difference in plants as you enter a wood, run a 20m tape measure into the wood and identify the plant every two metres.

Question 22

How would you investigate the effect of a stream running through grassland?

Answer 22

To investigate the effect of a stream running through grassland you would run a tape measure at right angles across the stream and record the species of plant touching the tape measure every 1m. The environmental factor being investigated is moisture content of the soil.

Question 23

Explain the Belt transect method

Answer 23

• This method enables you to collect data on the abundance of different species along the transect
• After running the transect across the area being studied, you place a quadrat at even distances along the tape measure
• estimates: density, percentage frequency and percentage area cover.
• yields more data but is only practical over a short distance unless you have a lot of time
• As there is an environmental gradient, it is useful to measure the factor that varies, so in each quadrat, you could measure, for example, the light intensity. You could plot the density, percentage frequency or percentage area cover of your species against the light intensity.