PAG 3 Sampling techniques

Question 1

sampling methods needed for an unbiased valid measure of biodiversity

Answer 1

random sampling
use of quadrat/transect line
place quadrat at regular intervals
use a key to identify
count organisms in the sample
many repeats at different times of the day/season

Question 2

random sampling

Answer 2

establish coordinate graph for a habitat

use a random number generator to generate x and y coordinate

sample the area corresponding to the number generated —> place quadrat (bottom left hand corner at the point generated)

Question 3

why is the use of a key important?

Answer 3

to ensure the correct species is identified

prevents the misidentification of species

ensured validity

Question 4

how would you count the number of organisms in the sample using a quadrat?

Answer 4

count all organisms inside the quadrat square

do not count any organisms which are half in/out of the quadrat

Question 5

why is it important to repeat at different times of the day?

Answer 5

increases the reliability of the data

large sample size = more representative

Question 6

why is sampling important in measuring biodiversity in a habitat?

Answer 6

not possible to count every individual organism in a habitat

sampling provides an estimate which can be representative of the entire ares

Question 7

why would you take samples of two different areas in a habitat?

Answer 7

to be able to compare data

Question 8

what do species evenness and richness show when assessing biodiversity?

Answer 8

both show whether there is a dominant species or not

high species richness and evenness is associated with high biodiversity

Question 9

what would a low value for Simpon’s indicate?

Answer 9

the presence of a dominant species

shows that the habitat is less likely to cope with changes to the environment or the introduction of a disease

Question 10

when counting animals/insects what precautions must be taken?

Answer 10

collect at different times of the day/season
method to capture the insect
use a key to correctly identify
mark the insects to ensure they are not counted again

Question 11

methods to capture insect

Answer 11

pooter
sweep net
pitfall trap
kick sampling

Question 12

how can data be eyeballed to see species richness?

Answer 12

look at the number of individual species

Question 13

how can data be eyeballed to see species evenness?

Answer 13

look at the range

smaller range = more evenness

Question 14

types of systematic sampling

Answer 14

belt transect
line transect

Question 15

what are the limitations of systematic sampling?

Answer 15

only runs in one direction so not representative of entire habitat

without a key misidentification can occur

if not done on different days or at different times

if not repeated for a larger sample size

when plants not in a quadrat are counted (in or out?)

Question 16

what is the benefits of using a point quadrat?

Answer 16

less subjective than point quadrat
able to establish correlations over a distance
you only count what touches the point

Question 17

what are the limitations of point quadrat?

Answer 17

less representative as plants in abundance may not be present at a specific point

Question 18

what is the main method of sampling to investigate succession?

Answer 18

belt/line transect

Question 19

outline use of transect line

Answer 19

use transect line and place point quadrats at regular intervals

count the relative abundance of each species

use a key to identify the species

repeat at different times of the day and different seasons

Question 20

when comparing two fields/habitats what should be controlled?

Answer 20

size of field
pH/nutrient content of field
time of day
season
sampling method

Question 21

ways in which validity of a sampling technique for an investigation can be increased

Answer 21

use key to identify species
mark organisms to prevent recounting
repeat at different times of the day
repeat at different seasons/climate
collect in a a large area