Practical skills and research methods Flashcards
when is random sampling used?
-fairly uniform areas for studying the distribution of pants/animals that don’t move much
When is systematic sampling used?
Where the environment/species gradually change (environmental gradient)
In systematic sampling the samples are taken at….
regular/predetermined intervals
True or false systematic sampling NEVER uses quadrats
False : used in belt transects
Why is random sampling used?
- to reduce/eliminate biased
- data is representative = allows for a statistical test
Consideration when using quadrats:
- The size of the quadrat (depends on ____ of species and _________)
- the ______ of samples taken in area (the ____ samples the more ______ the results)
- The ________ of the quadrat
- size, distribution
- number, more,reliable
- position
How many repeats should be taken?
- A large _____ to make results _______
- Enough to carry out ________ test
- Calculate a _____ ______
- When a _____ ______ shows little change=________
- If the work can be carried out in the _____ available
- number, reliable
- statistical
- running mean
- running mean, stop
- time
What is a line transect?
Tape measure on ground, straight. Check at specific points/intervals
a pro and con of a line transect
pro: easy to use
con: may miss species as only counting if the species is there is it touches transect
what is a belt transect?
a tape measure, use quadrat along tape measure at set intervals
a pro and con of a belt transect
pro: gives info on abundance
con: takes longer than a line transect
What is species diversity?
no. of different species that are represented in a species community
What is the equation called which gives species diversity?
Simpsons Index
What 2 pieces of info do u need to calculate species diversity?
Total no. of all organisms of all species
Total no. of organisms in each species
When talking about representative data what 5 things do u need to include?
location, method, timing, standardising, sample size/repeats
What is the equation called for mark release recapture?
Lincoln index
In MRR the higher the proportion of _______ sample recaught, ________ population estimate.
original, decreases
Name 3 assumptions of MMR method
some individuals more likely to be recaught
Was there sufficient time for reintegrating organism
territorial individuals
Marking may impact survival of organisms (more predated)
births, deaths, migration
When do you stop sampling ?
when the running mean levels out
repeating many times= ?
increase validity
standardising kick sampling? what is it used for?
same person kicking, same size mesh (net), same no.of kicks
- used for aquatic invertebrates
standardising surber nets and why is it easier to standardise? what is it used for?
same size nets/mesh, how long it is left
as it is not influenced by person
- used for sampling aquatic invertebrates
standardising pooter? what is it used for?
time you spend sampling/catching organisms
- used for small insects
standardising sweep nets? what is it used for?
no. of sweeps, size of net
- used for butterflies/flying insects in long grass/ vegetation
standardising light trap? what is it used for?
light intensity, same time leaving it out, same light bulb
- for sampling night flying moths
standardising beating tray? what is it used for?
same force of hitting, same no. of hits, same size tray
- used for overhanging vegetation
standardising colonisation media? what is it used for?
time of year you are leaving, same type of material
- study species that colonise/populate over time
standardising tullgren funnel? what is it used for?
check regularly, same size sieve, light intensity of bulb, sample sample size of soil/leaf litter
- used for insects/invertebrates living in soil/leaf litter
When sampling earthworms in a lab you would use the _______ _______. in the field you would use a _______ and an ______ solution i.e. mustard powder. Leave for 2 mins to let it ____ in, 5 mins ____, then count worms. How would you standardise?
tullgren funnel, quadrat, irritant, sink, wait
standardise by same size quadrat, same volume of irritant, same type of solution, time you leave it
When answering question on methods on sampling what 4 things have you got to include?
- justified no.of sample size
- sample location
- timing
- standardising
What do electronic meters measure? and examples.
abiotic factors (pH, light levels, temp, dissolved oxygen, wind/water velocity, water turbidity)
Name the old and the new method used for measuring humidity
whirling hygrometer (old) electric humidity meter (new)
How do you measure wind velocity?
electronic anemometer
what are the two methods to measure water turbidity?
secchi disc and turbidity bottle
What are the limitations of using a secchi disc
depth is subjective, sunlight affect visibility, water may not be deep enough to no longer see sectors
limitations of using a turbidity bottle
distinguishing circles are subjective, light levels affect visibility
What are the 2 methods to assess soil texture
soil sieves and sedimentation
what mineral particles do we assess in soil texture ?
sand, silt and clay
Put these in order in which they take shortest to longest for them to settle during sedimentation: silt, caly, sand and how long.
shortest: sand (2 mins)
middle : silt (2 hours)
Longest: clay (2 days)
Name the 3 methods used to measure concentrations of ions in solution plus limitation
- test strips
- electronic colourimeter
- ion selective electrodes
Limitation: presence of other ions can lead to inaccurate results
The limitation of universal indicators are…….
that they are subjective
Name 3 methods to test soil pH
universal indicator, universal indicator papers, electronic pH meters
Limitation of electronic pH meter?
that you need to calibrate regularly
What is the equation for estimated % water content?
% H2O content = wet soil mass - dry soil mass/wet soil mass then x100
What is the equation for % organic matter content in soil?
% organic matter content = dry soil mass - burnt soil mass / dry soil mass x 100
what is the equation for soil bulk density?
bulk density = weight of dry soil / total soil volume
sample size and timing can be determined by…..
a preliminary study
