11.2 sampling

What is sampling?

Selecting a representative group of organisms from a habitat to estimate the biodiversity of the whole habitat.

Why is sampling used to measure biodiversity?

It is impractical to count every organism in a habitat, so sampling allows estimates to be made.

Why is representative sampling important?

It reduces bias and makes estimates more reliable.

What is random sampling?

Selecting sampling locations entirely by chance, giving each location an equal chance of being selected.

How is random sampling carried out?

Use random coordinates generated within a defined sampling area, then collect samples at those locations.

What is non-random sampling?

Sampling where locations are selected using a particular method rather than entirely by chance.

What are the three types of non-random sampling?

Opportunistic, stratified and systematic sampling.

What is opportunistic sampling?

Collecting samples from organisms or locations that are easiest to access.

What is a disadvantage of opportunistic sampling?

It is prone to sampling bias and may not be representative of the habitat.

What is stratified sampling?

Dividing a habitat into distinct areas (strata) and sampling each area separately.

Why is stratified sampling useful?

It ensures different areas or habitats are represented in the sample.

What is systematic sampling?

Collecting samples at regular intervals along a transect or within a sampling area.

Why is systematic sampling useful?

It shows how the distribution of organisms changes across a habitat or environmental gradient.

What is the importance of sampling a range of organisms?

It provides a more representative estimate of the biodiversity within a habitat.

What can affect the reliability of biodiversity estimates?

Sample size, sampling method, sampling bias and the range of organisms sampled.