Transects & Quadrats

Question 1

What is sampling and what is it used for?

Answer 1

• used to measure biodiversity of a habitat or abundance of a species
• it is impossible to count all species so we need to take sample
• sample needs to be representative of the whole habitat / ecosystem - need a few
  repeats
• use sample data to extrapalate to estimate the total number of
  individuals in the habitat

Question 2

What are the rules of sampling?

Answer 2

• Large sample size / lots of repeats
• sample at different times of day or year or weather conditions
• standardise sampling methods e.g. height
• take measures to avoid capturing the same individual twice
• calculate means
• use a statistical test

Question 3

What are the two types of sampling?

Answer 3

random sampling and non random sampling

Question 4

What is random sampling?

Answer 4

• to avoid bias
• divide the sampling area into a grid
• use a random number generator to pick coordinates

Question 5

What are the random sampling for plants, mobile animals and flying insects?

Answer 5

plants - quadrats
mobile animals - traps
flying insects - sweep nets

Question 6

What is systematic sampling in non random sampling?

Answer 6

• samples are taken at fixed intervals e.g. transect

- measures a change in the enviroment e.g. change in vegetation moving away from high tide line

Question 7

What is opportunistic sampling?

Answer 7

sample sizes are chosen by investigator

will be biased

easy and fast to do

Question 8

What is stratified sampling?

Answer 8

• survey area is divided into groups

- each area is surveyed separately - in proportion to its coverage of total area