4.1.2: Biodiversity: Sampling Flashcards
What is the purpose of sampling in measuring biodiversity?
To record data on every individual within a population would be too time-consuming and potentially impossible.
What is a key requirement for a sample to be representative of a population?
A large sample size must be taken and random sampling should be used.
What is the minimum sample size recommended for calculating a mean?
At least 30.
What does random sampling help to avoid?
Bias.
Describe a common method of random sampling.
Lay out two tape measures at right angles, generate random coordinates, and place a quadrat at those coordinates.
What are the three non-random sampling techniques?
- Opportunistic
- Stratified
- Systematic
What characterizes opportunistic sampling?
It involves sampling organisms that are conveniently available, leading to potential bias.
How does stratified sampling work?
Populations or habitats are separated into groups or strata, and random samples are taken from each group.
What is systematic sampling used for?
To identify different areas within a habitat to sample, especially when there is a change in species distribution.
What is a belt transect?
A method in systematic sampling where a tape measure is placed along the sample area and quadrats are placed at regular intervals.
What are quadrats used for?
To sample plants and slow-moving organisms.
What is the density method in sampling?
Counting the number of individuals present.
How is frequency measured in sampling?
Counting how many squares out of 100 a species is present in using a gridded frame quadrat.
What does percentage cover estimate in sampling?
The percentage of the entire quadrat covered with the species being investigated.
What is a limitation of the percentage cover method?
It is subjective and results in lower accuracy.
What is the purpose of sweeping nets in sampling?
To capture insects in long grass.
Describe how a pitfall trap works.
A hole is dug and a pot is placed inside; small invertebrates crawl in and cannot escape.
What is a pooter used for?
To capture very small insects using suction.
How does a Tullgren funnel extract organisms from soil samples?
Soil is dried with a heat lamp, causing organisms to move downwards into a collecting dish.
What is kick sampling used for?
To sample organisms within river beds by disturbing the substrate and capturing released organisms.
