1.1-b) Sampling Animals and Plants

Question 1

• Compare the differences between qualitative and quantitative data.

Answer 1

• Qualitative:
  ➞ is descriptive, and regards data that can be observed, but not measured.
  ↳ (used to inform on what species are present)
• Quantative:
  ➞ regards information about quantities, and therefore numbers.
  ↳ (allows for statistical analysis and interpretation of trends)

Question 2

• Describe the purpose of a representative sample?

Answer 2

• Sometimes a population is so large that it would be impractical to sample every individual.
• In this case, a representative sample of the population is selected.
• If a population has a wide range of variations, then a larger representative sample is needed.

Question 3

• What are the 3 principles of a representative sample?

Answer 3

1. The sample should have the same mean as the population as a whole.
2. The sample should have the same degree of variation about the mean as the population as a whole.
3. The sample should be a large sample.

Question 4

• What are the 3 main strategies for obtaining a representative sample?

Answer 4

1. Simple Random:
   ➞ each member of the population has an equal chance of being sampled
   ↳ (e.g. random quadrat sampling)
2. Systematic:
   ➞ members of a population are selected at regular intervals
   ↳ (e.g. sampling an ecosystem every 10 metres along a transect)
3. Stratified:
   ➞ the population is divided into categories and then sampled proportionally
   ↳ (e.g. sampling of three distinct habitats)

Question 5

• Describe the importance of species monitoring.

Answer 5

• It is important to identify and monitor species for several reasons:
  1. monitoring population change 📉
  2. monitoring invasive species ❗
  3. monitoring pollution using indicator species ☢️
  4. monitoring the discovery of new species ✨

Question 6

• Discuss pollution monitoring and indicator species.

Answer 6

• Indicator species can be used to determine the impact of pollution on an environment.
  ➞ The presence, absence or abundance of certain living organisms show if an environment is affected by a particular set of environmental conditions.
  ↳ (e.g. Lichens can tolerate different levels of atmospheric sulfur dioxide)

Question 7

• Explain what the measurement ‘DENSITY’ is when using quantative techniques?

Answer 7

• Density:
  ➞ is the number of individuals of the same species pesent per unit area or unit volume.

Question 8

• Explain what the measurement ‘RELATIVE ABUNDANCE’ is when using quantitative techniques?

Answer 8

• Relative abundance:
  ➞ is how common or rare a species is relative to other species in a defined area or community
  (expressed as a percentage of the total number of organisms in an area)

Question 9

• Explain what the measurement ‘FREQUENCY’ is when using quantitative techniques?

Answer 9

• Frequency:
  ➞ is the chance of finding a species within a defined area and the number of percentage of samples in which a particular species occurs
  ↳ (e.g. a quadrat)

Question 10

• Explain what the measurement ‘PERCENTAGE COVER’ is when using quantitative techniques.

Answer 10

• Percentage cover:
  ➞ is a measure of the amount of cover of a particular species in a quadrat.

Question 11

• Explain what the measurement ‘DISTRIBUTION’ is when using quantitative techniques?

Answer 11

• Distribution:
  ➞ is the manner in which a group is arranged geographically and can change seasonally, in response to resource availability and in response to other external factors.

Question 12

• Explain what a transect is.

Answer 12

• A transect is a sampling method which investigates the distribution of organisms in relation to a fixed area by recording all the species found at points, or in a quadrat placed in certain intervals along a line.

Question 13

• Explain the 3 different methods for using transects.

Answer 13

1. Line:
   ➞ A line is drawn through the habitat.
   Any species touching the line is counted and recorded (e.g. a piece of string placed along a habitat and the number of dandelions touching the line can be counted).
2. Belt:
   ➞ A quadrat is placed continuously along a transect line of a known length and width (e.g. quadrats placed continuously along a line of a river bank).
3. Point:
   ➞ Sampling using simple, random, or systematic methods at known points along the transect line (e.g. quadrats placed every 10m along a transect line).

Question 14

• What are the limitations of using quadrats to sample the environment and the potential solutions?

Answer 14

1. Organisms in a quadrat may be wrongly identitified
   ➞ a.) use a resource (e.g. internet) to identify unknown organisms (+ paired statement keys, reverse imageing, photographs, etc)
2. Organisms in a quadrat may be wrongly counted
   ➞ b.) Establish a common rule for counting organisms (i.e. plants/organisms that are half in/out)
3. Sample may not be representative of the ecosystem
   ➞ c.) Take several samples and calculate an average (mean)

Question 15

• Explain the ‘capture-mark-recapture’ technique (Lincoln Biodiversity Index)

Answer 15

• The ‘capture-mark-recapture’ technique can be used to estimate the size of a population (invertebrates and vertebrates)
• After random sampling has been carried out, the Lincoln Biodiversity Index can be used to determine an estimate of the total population.

1. A sample of the population is captured and marked (M) and released.
2. After an interval of time, a second sample is captured (C)
   ➞ (which allows the population to mix - to have an equal chance of all members of the population to be in the second sample)
3. The number of recaptures (R) in the second sample is counted.
4. The total populaton is found using the formula:
   ➞ Total population (N) = (M x C) /R

Question 16

• Compare the lists of invasive and non-invasive sampling techniques.

Answer 16

• INVASIVE:
  1. Quadrats
  2. Pitfall traps
  3. Net sampling
  ➞ Sweep nets (insects)
  ➞ Mist nets (birds/bats)
  ➞ Drip nets (fish)
  4. Capture-mark-recapture
  5. Tree beating
  6. Pooters
• NON-INVASIVE:
  1. Drones
  2. Camera traps
  3. Thermal cameras
  4. Observational data
  5. Audio recording
  6. Motions sensor cameras
  7. Faecal sampling
  8. Hair trapping

Question 17

• What is a biotic indice?

Answer 17

• Biotic indice:
  ➞ is a scale showing the quality of an environment based on the types of organisms that inhabit it.

Question 18

• What is the Trent biotic index?

Answer 18

• Trent biotic index:
  ➞ a measure which uses freshwater invertebrates to compare water quality at different points in a stream or river.
  ↳ These species are indicator species, which give information regarding the quality of the environment based on their presence, absence, or abundance.
• Scores range from 0 for highly polluted water to 15 for clean water.

Question 19

• What is the Simpson’s diversity index?

Answer 19

• Simpson’s diversity index:
  ➞ a measure of diversity which takes into account the number of species present, plus the relative abundance of each species.
• The value of D ranges from 0 to 1:
  ➞ 0 represents infinite diversity = better health of an ecosystem
  ➞ 1 represents no diversity = worse health of an ecosystem

Question 20

• Explain ‘validity’.

Answer 20

• Validity:
  ➞ is the measure of how well a test measures what it is meant to measure (related to variables)

Question 21

• Explain ‘reliability.

Answer 21

• Reliability:
  ➞ is the ability of an experimental design to give stable and consistent results (measure of consistency)

Question 22

• Suggest ways in which the validity of sampling could be increased.

Answer 22

1. Ensuring your variables are kept constant
2. Ensuring sampling time/location is kept the same
3. Using multiple sampling methods to confirm this trend (triangulation)
4. Comparing findings from your study to previous studies

Question 23

• Suggest ways in which the reliability of sampling could be increased.

Answer 23

1. Taking more samples
2. Repeating the experiment
3. Using a larger number of pieces of sampling equipment (e.g. multiple bat detectors)