Coursework: Measuring biodiversity

Question 1

What is biodiversity?

Answer 1

The variety of life - The range of living organisms to be found. This includes different species as well as variations within a specie.

Question 2

What is is a species?

Answer 2

A group of individual organisms very similar in appearance, anatomy, physiology, biochemistry and genetics; whose members are able to inbreed freely to produce fertile offsprings.

Question 3

What is a habitat?

Answer 3

A place where individuals in a species live. It usually has a specific set of conditions with living organisms living in it usually well adapted.

Question 4

What does biodiversity encapsulate?

Answer 4

1. The variety of different habitats found in a specific location.
2. Differences between each species; either anatomically, physiologically…
3. Genetic variation between members of the same species.

Question 5

How are samples taken randomly?

Answer 5

1. Samples are taken across the habitat at regular intervals.
2. A grid is laid over the habitat and random numbers are generated with a random number generator that are used to obtain random sampling coordinates.
3. Alternatively, the grid can be one found on a map. The sampling spot is then found with a GPS.

Question 6

How is sampling size determined?

Answer 6

Sampling size is dependent on the biodiversity of the habitat itself. If the habitat looks diverse, then more samples should be taken to ensure that rarer/ more concentrated colonies of species are included in the sample. If the habitat doesn’t look diverse, less samples will need to be taken. However, when comparing two habitats, the same number of samples should be taken.

Question 7

How are plants sampled?

Answer 7

Plants are usually sampled using quadrats, squares varying in size used for defining the sampling area.

Question 8

What is species richness?

Answer 8

The number of species present in a habitat.

Question 9

What is species evenness?

Answer 9

A measure of the species richness taking into account the number of individuals of that species (population) within a given habitat.

Question 10

How is species richness determined?

Answer 10

Using a quadrat. The number of different species that can be seen within the quadrat are usually counted and noted.

Question 11

What limitations are there with this method?

Answer 11

1. It may be difficult to distinguish between different species if they have similar appearances.
2. Smaller, more insignificant plants may be missed.
3. Seasonality may affect the number of species that can be seen within the sampling area.

Question 12

How can species evenness be determined?

Answer 12

1. The number of individuals of a species can be counted within a quadrat.
2. A visual survey can be done of the quadrat and a measure of abundance can be giving using the ACFOR scale.

Question 13

What are the limitations with this method?

Answer 13

1. Difficult to distinguish between different species and indeed different individuals.
2. There may be too many individuals to count.
3. Smaller, more insignificant plants are harder to see and therefore their numbers are usually underestimated.

Question 14

What is a better way of estimating species evenness?

Answer 14

Using percentage coverage of different species.

Question 15

How can % coverage be determined?

Answer 15

1. The quadrat can be split into smaller squares, % coverage can be estimated within these smaller squares and totalled at the end.
2. A point frame can me used. These are frames with usually a series of 10 needles/ pointers mounted onto them (with the same width as the quadrat). These are moved across the quadrat 10 times and plants touching the pointers are recorded.

Question 16

What are the limitations of using a point frame?

Answer 16

1. Smaller, insignificant plants can be missed.

2. More than 1 plant can be touching the pointer with each measurement, giving a % coverage of over 100%.

Question 17

How can species evenness be quantified?

Answer 17

By using Simpson’s diversity index; 1 - [sum(n/N)^2], where n = number of individuals in a particular species and N = total number of individuals in all species. A higher Simpson’s index indicates a greater species evenness.

Question 18

What factors need to be kept the same when comparing different habitats for results to be valid?

Answer 18

1. Number of samples.
2. Standard procedure; results should be collected in the same way.
3. Other variables; including obvious factors that may affect biodiversity including shade or human factors.

Question 19

What is accuracy?

Answer 19

Accuracy is how close the values obtained by the experiment is to the true value. This can be determined by commenting on the uncertainties, the apparatus/ experiment or the data obtained with other data.

Question 20

What is reliability?

Answer 20

Reliability considers how good the data obtained is. This can be determined by looking at the spread of the data and can be improved by doing more repeats so outliers contribute less to the final mean.

Question 21

What is precision?

Answer 21

Precision is the degree of accuracy a measurement is taken to and is determined by the apparatus and the experimental method.

Question 22

What is validity?

Answer 22

Validity is how good the results are as a representation of the original hypothesis, considering any factors that may have distorted the data.

Question 23

How can range bars be interpreted?

Answer 23

1. Large range bars usually mean bigger spread of data, thus more unreliable data.
2. When comparing 2 sets of data, if range bars overlap, we cannot confidently say the 2 sets of data are different.
3. The size of the overlap determines how confident we can be of a clear difference between the data sets.

Question 24

What factors may contribute towards different biodiversities?

Answer 24

1. Different light exposure.
2. Different consumers present.
3. Level of human activity.
4. Wind exposure.
5. Soil type and quality.
6. Disease.
7. Availability of water.
8. Mineral content of soil.
9. pH of soil.