11.3 - Sampling Techniques

Question 1

State the 5 animal sampling techniques.

Answer 1

1. Pooter
2. Sweep Nets
3. Pitfall Trap
4. Tullgren Funnel
5. Kick Sampling

Question 2

Describe how kick sampling and a Tullgren funnel works.

Answer 2

Tullgren Funnel:

• Used to extract invertebrates from soil or leaf littter
• Place the sample in a funnel above the perforated disk
• Shine a bright light over the funnel
• Rise in temp. and drying effect will force the organisms to move and fall through the disc into a collecting funnel (takes 2-3 days)
  
  • Insects land into a preservative liquid such as alcohol

Kick Sampling: Studies organisms in rivers. River bed/bank is kicked to disturb substrate, a net is held downstream to capture flowing dislodged organisms

Question 3

Describe how a pooter,** **sweep net** & **pitfall trap works.

Answer 3

Pitfall Traps: Catch small crawling insects. Dig hole in ground, deep enough so insects cannot crawl out. Have a roof-prop above the hole. Leave trap overnight (for nocturnal). Sample

Sweep Nets: They catch insects in areas such as long grass.

Pooter: 2 tubes present inside a chamber. One connceted to the insect habitat, one in your mouth. Both feed into a tube, suck on it to draw insects in

Question 4

State and describe the 2 plant sampling methods.

Answer 4

Point Quadrat: Uses a frame with a horizontal bar. Long pins along the bar can be pushed into the ground. Each species of plant touching the pin is recorded

Frame Quadrat: Square frame, divided into a grid. Type and number of species in each section is recorded

Question 5

How is species richness measured?

Answer 5

• Use a combination of techniques to identify all species in a habitat
• Produce a list of the species and calculate the total number of species.
• Identification keys are used – help scientists identify organisms – may contain images, or a series of questions based on the presence of characteristics to identify the species.

Question 6

How is species evenness measured?

Answer 6

Identify the number of each species to decide the evenness of species spread in a habitat.

Question 7

Describe the 3 ways to sample using a frame quadrat.

Answer 7

Density – count number of plants in 1m by 1m square quadrat – gives density per m² - an absolute measure, not an estimate.

Frequency – used where individual members of species are hard to count (e.g. grass). Use frame quadrat, in each grid count the number of plant species present. If there are, for e.g. 65 clovers present in 100 squares, there is an estimate 65% coverage.

Percentage cover – used for speed, useful when a species is abundant or hard to count. Eye estimate of the area within a quadrat a plant covers

Question 8

Describe the method used to estimate animal population size.

Answer 8

• Animals are constantly moving through their habitat, so counting them is difficult
• Capture-mark-release-recapture is used – capture as many individuals of a species as you can, mark them in a way that doesn’t harm the animals, or inhibit their survival chances, then release them. This gives them time to redistribute. Capture as many as you can again.
• The greater the number of marked organisms recaptured, the smaller the population

Question 9

Define abiotic factor and give some examples.

Answer 9

Non-living conditions of a habitat. {light intensity; water; pH; temperature etc.}

Question 10

What are the sensors and units used for each abiotic factor?

Answer 10

Wind speed

Anemometer

ms^-1

Light intensity

Light meter

lx

Relative humidity

Humidity sensor

mg dm³

pH

pH probe

pH

Temperature

Thermometer/Temp. probe

⁰C

O₂ content in H₂O

Dissolved O₂ probe

mg dm³

Question 11

What are the advantages of using accurate sensors?

Answer 11

• Rapid changes can be detected
• Reduced human error
• High precision degree
• Data can be stored and tracked for analysis