sampling

How can u ensue your sample is representative

Take larger sample

Calc mean and take statistical tests to see if there are any differences o correlations you see are significant

Random sample

How would you do random sampling

Create griddle area (lay out 2 measures at right angles

Use random number generator to give 2 coordinate numbers

What is the method of using a point quadrat and what is it used for

Point quadrat is used for sampling plants and slow moving organisms

It’s a horizontal bar with holes at set intervals that long pins can be placed through

Pin is pushed through to touch ground - any species touching pin is recorded

What is another type of quadrat instead of point

Frame quadrat

What are the 3 non random sampling

Opportunistic

Stratified

Systematic

What is opportunistic sampling used for and what’s bad about it

The opportunistic - sampling organisms conveniently available

• bias

• Doesn’t accurately represent pop

What is stratified sampling used for

Stratified sampling is used for same pop and habitats separated into groups to sample from

What is an example of stratified sampling

Sampling a pond

Divide into 3 parts

Strata each sample (random sample) within each group

What is systematic sampling used for? And what is the method

Systematic sampling is used for identifying different areas in a habitat to sample

Used to investigate when there has been a change in biodiversity due to change in distribution of species

Involves tape transect and at regular distances place quadrat

What are the 3 methods of using a quadrat

Density - count in individuals present

Frequency - quick/ requires gridded frame quadrat with 100 squares And count how many squares your species is present in

Percentage cover - estimate the number of squares with species - its quick and subjective - lower accuracy

How can u improve the percentage cover method

Standardising how percentage is estimated

E.g counting 1% for every small square that is at least half covered with plant

What are sweeping nets used for

Capture insects in long grass

What is a pitfall trap used for

It’s a ole dug

Pot paced within

Small invertebrates crawl in - roof put on top to prevent tings from outside getting in - collected every day and let out

What is the funnel method called and what is it

Tulgren funnel

Extract small samples within soil samples

• this dried using heat lamp - animals then move in opposite direction (down) where a collecting dish is plated

What are pooters used for?

Captures small insects

2 tubes connected to a closed pot

Investigator sucks on one tube and places the other tubes over the insect - suctions insect out and into pot.

What is the sample method including 2 people and a net

Kick sampling

Sample organisms within river beds

1st investigator - gently kick river bed to disturb earth + organisms within

2nd investigator - stands behind with a net to capture any organisms released.

How to record species evenness

Count different species and each individual within the species to work out relative abundance