4.1.3 Sampling Techniques

Question 1

Point sampling

Answer 1

• Estimate population by counting individuals at selected points
• Points random or predetermined
• Pro: broadly establishes kinds of organisms present in an area
• Con: may miss some species

Question 2

Quadrat sampling

Answer 2

Estimate number and kinds of organisms in a larger area by counting in 1sqm quadrats

Pro:
- Broadly establishes kinds of organisms present in an area

Con:
- May miss some species
- Location may be biased

Question 3

Quadrat population density

Answer 3

Total no. in all quadrats/(no. of quadrats x area of one quadrat)

Question 4

Transect sampling

Answer 4

• Line marked through a habitat
• Investigate distribution of a population across an area with different abiotic factors

Pro:
- Can assess variation in community composition throughout the habitat
- Time efficient
- Minimal disturbance to environment

Con:
- may miss species of low abundance

Question 5

Capture/Recapture

Answer 5

Organisms are captured and tagged, and can be identified later in the study.
Form of representative sampling: sample assumed to accurately represent entire population

Pro:
- Avoids double counting
- Can track trends across time
- Able to track/count mobile population

Con:
- Time consuming

Question 6

CMR estimated population is

Answer 6

no. initially tagged * no. consequently tagged
_________________________________________________
no. of recaptured tagged individuals