Sampling Flashcards
What is the result of sampling?
An estimate number in the whole habitat
What is sampling?
Counting the number of species and number of individuals in each species in a small proportion of the habitat
What does sampling allow?
Predictions and generalisations about number, type of species, distributions of organisms and their traits
What is a minimum to sample?
10%
What are the issues with sampling?
It is never entirely representative due to sampling bias or chance
What is sampling bias?
Selection may be biased either by accident or on purpose
How do you reduce the effect of sampling bias?
Random sampling where no human involvement in choosing
What is chance?
Organisms selected may be by chance and aren’t representative
How can the effects of chance be reduced?
By using a larger sample size
What are the 2 types of sampling?
Random and non random
What is the method of random sampling?
- Use a grid of measuring tapes
- Random number generator gives co-ordinates
- Sample at the point
What are strengths of random sampling?
It avoids bias, each area has the same probability of being chosen and you can analyse statistically
What are the 3 types of non-random sampling?
Opportunistic, systematic and stratified
What is opportunistic sampling?
Sample organisms that happen to be present so might not be representative
What is systematic sampling?
Sample different identified areas using a transect
What is stratified sampling?
Divide organisms into subgroups and sample according to size of group
What are strengths of non random sampling?
It can measure the variety of distribution patterns at the site and good to measure change
How do you measure population size?
Mark, release and recapture
What is the equation to measure population size?
N = Mn / m
What is N?
The populations size to be estimated
What is M?
The number of members of the population that are captured and initially tagged
What is n?
The number of members of the population that are captured subsequently
What is m?
The number of members of this subsequent captured population that are tagged
What are the types of quadrants?
Frame, grid, and point
What is a frame quadrant?
A square sub-divided frame for easy estimation
What is a quadrat used for?
Non-mobile species
How do you use a frame quadrat?
Count number of individuals or estimate percentage cover when cannot count
What is a grid quadratic?
Has 100 squares so better estimate for percentage cover so can count better
What are quadrats used to measure?
Density, frequency and percentage cover
How do you measure density using a quadrat?
If an individual plant can be seen, count number per quadrat
What is a strength of calculating density?
It is an absolute measure instead of an estimate
How do you measure frequency using a quadrat?
Work out frequency of occurrence per quadrat
When do you use frequency?
When individual members of a species are hard to count
When do you use percentage cover?
For speed
How do you measure percentage cover using a quadrat?
Eye estimate of area within quadrat that plant cover
What are line transects?
Mark a line along the ground and take samples at specified points
What is a belt transect?
Two parallel lines are marked, and sampled are taken of marked area
How do you use a line or belt transect?
Place a quadrat at either intervals or continuously along tape measure
What is a line or belt transect used for?
To measure change over a distance
What is a point quadrat?
A frame contains a horizontal bar and at set intervals, long pins are pushed through bar to reach the ground
When do you use a point quadrat?
In dense vegetation or deeper foliage
What are ways of sampling animals?
Capture, tree beating, tull green funnel, light traps, pooters, pitfall traps and mammal trap
What is the capture method of sampling animals?
Use a sweep net or kick net where sticks and mud are kicked up then net is brought through water
What is tree beating?
Hit the tree and small animals are knocked out of tree into the net
What is a tullgren funnel?
Leaf litter is place in funnel and the light drives the animals downwards as the litter dries out, they fall through mesh screen into collecting jar with preservative
What are light traps?
Used to collecting moths and flying insects as attracted to the light
What are pooters?
Used to suck up insects or small animals for investigation, gauze/filter prevents inhalation of animals
What are pitfall traps?
Used to collect small animals, leave out for 24h then remove
What are mammal traps?
The door closes once a mammal walks into trap, have to be checked frequently due to starvation or dehydration
What are advantages of measuring abiotic factors?
Rapid changes can be detected, human errors are reduced, high degree of precision and data can be stored and tracked
How do you measure wind speed?
Anemometer
How do you measure light intensity?
Light meter
How do you measure relative humidity?
Humidity sensor
How do you measure pH?
pH probe
How do you measure temperature?
Temperature probe
How do you measure oxygen content in water?
Dissolved oxygen probe
How do you measure temperature of soil?
Soil thermometer
How do you measure acidity/alkalinity of soil?
Soil pH tester
How do you measure nitrogen concentration?
Nitrate detector
How do you measure mositure?
Moisture meter
How do you measure levels of light?
Light meter
How do you identify plants?
Key and loop (magnifying glass)
