practical skills Flashcards
why should you have a large sample size?
increased reliability of data + more representative
when should you use systematic sampling?
when about distance, samples are taken at (named) regular intervals
when should random sampling be used?
when the area is uniform, used for studying distribution (of plants or animals that don’t move much)
when should a transect be used?
if there is an environmental gradient
what’s the difference between a belt vs. line transect?
belt = with quadrat along the transect
- gives info on abundance but may be potentially more damaging
line = no quadrat, just whatever’s touching the transect directly
- quick + easy
why use random sampling?
-eliminates bias - data is representative
-allows use of stats test
what are some considerations when using quadrats?
- the size of quadrat (based of size of species + distribution)
-number of samples taken in an area - [min 10, until running mean levels out]
-position of each quadrat - random no. generator + coordinates
^(calc. = Rnd#1-10) eg. 10Rnd#
-type of quadrat eg. gridded
how many repeats should one do?
minimum 10 (more = better)
- large enough number to ensure reliable data
- enough to carry out a stats test
-until running mean levels off with little fluctuations
^any more = waste of time, not efficent
what’s the calculation for: population density
population density = number/area
(individuals m^2-1) (m^2)
how do you work out % cover?
estimate of area covered in quadrat
which area is more species diverse: index of 1.5 or 2.7
2.7! - higher no.= more diverse
when do you use %cover?
if species abundant is difficult to count individuals eg. moss
+ data collected very quickly
why calculate frequency?
gives an idea of what species are present eg. is 13/30 quadrats have species.. frequency =43%
dis = no info on pop. density
what is a representative sample?
a sample/ small portion of the total that accurately reflects the entire population
whats the ideal sample size?
samples until the running mean levels out
how does one ensure their results are representative?
standardize!!!!!!!
eg. what, where, when, how, how many etc..
^^keep all the same BUT the IV
+large enough sample size
describe the steps of mark recapture release
-capture no. of animals
-carefully mark them
-release them + allow time to re-integrate with pop.
-collect 2nd sample
-count + record no. of marked + unmarked
-use Lincoln index to estimate pop. size
what is Lincoln index + what is it and MRR used for?
estimating population size:
total pop. = number or organisms in sample 1 x
. number of organisms in sample 2
. —————————————————
. number of marked organism in sample 2
what does MRR assume?
- no natural population change ie. no deaths, births, migration etc..
-there is enough time/ the population is fully re-integrated/mixed
-all organisms have an equal likelihood of getting caught
-the marks are don’t rub off/ the individuals are identifiable
-the sample size is large enough
how can data be made scientifically valid?
-do a large amount of samples
- collect samples at different times of day, season, and year etc..
what should you do if the question says “use the information”
quote data!!!!
what does -1 at the end of a unit mean?
per
ie. LU-1 = per livestock unit
what should be done if you don’t know the calculations for a maths question
multiply or divide and then pick the most reasonable answer
what is the structure for a practical question
technique, representative and data collected
what is meant by ‘representative’ in the structure of a practical question answer
- location and timing - systematic or random (always say one!!)
- number of repeats (for reliable data +/ carry out a stat test)
- standardisation
- sample size
name three factors for areas that should be standardised if they are not being investigated
climate, temperature, vegetation, time of year/ season etc..
name 10 lowkey sampling techniques
- kick sampling
- surber samplers
- suction samplers/ pooters
- pitfall traps
- sweep nets
- beating trays
- transect lines
- quadrats
- light traps
- tullgren funnel
- collection of earthworms
- indirect evidence
why use a beating tray
to sample populations of invertebrates attached to overhanging branches of shrubs or trees
describe how to use beating trays
a tray/ sheet is placed under a branch, the branch is hit repeatedly with a stick, invertebrates are dislodged and fall off
what are the limitations of beating trays
- hard to standardise force of branched striking
- some species are more easily dislodged than others
- not all branches can be reached
name ways to standardise the use of beating trays
- the size of the tray
- the number of hits
- weather conditions
- time of day/ year
describe how to use transect Lines
-line placed along an environmental gradient
- samples taken at points along the line 9
name a limitation of transect lines
only representative data if transect is typical of area of study
name ways to standardise transect Lines
-distance between points
- weather conditions
- time of day/ year
name an advantage of quadrats
can calculate frequency and percentage cover
name a limitation of quadrats
-May involve selective judgement eg. percentage cover
-frame may flatten/ damage vegetation
why use light traps
to sample populations of insects attracted to bright lights - usually night flying insects
describe how to use a light trap
light trap is left overnight, bright light attracts flying insects into trap
name a limitation of light traps
light may be more attractive to certain species
name ways to standardise light traps
- wavelength of light
- power / brightness of light
- size and type of trap
- time left outside
- weather conditions
- time of year/ ear season
why use a tullgren funnel
to sample populations of mobile invertebrates in soil/ Leaf litter
describe how to use a tullgren funnel
soil/ Leaf litter placed on mesh tray with light above, invertebrates are repelled by light and move downwards into the pot
name some limitations of tullgren funnels
-not all species are repelled by light/ heat
- some species are too large to pass through the mesh
- organisms may die due to heating
why use photographic surveys
to sample large organisms or those that tend to be rarer with low population densities
describe the use of photographic surveys
motion sensitive cameras are used to estimate abundance or aerial photographic surveys if there is open land
name some limitations of using photographic surveys
- some species are more likely to be spotted
- some individuals may trigger the camera multiple times
describe sampling by indirect methods for sampling
markers used to identify individuals that are exclusive or too rare to be seen normally
- markers can range from:
- droppings
- nests/ Burrows
- footprints/ tracks
- territorial marks
-(sometimes DNA analysis)
with these, population abundance can be determined
name a limitation of using indirect evidence for sampling
-may require technology to analyse and determine different individuals
- organisms are not actually seen
- only impressions and opinions, not hard evidence
why use the collection of earthworms
to sample earthworm population in soil
describe using collection of earthworms
-area of soil is flooded with irritant solution (eg. dilute acid, mustard water etc..)
-area is marked out with quadrat
- soil is observed for set time
- worms may appear and be collected
some limitations of using the collection of earthworms technique
- differences in soil will influence results
- some worms may escape by moving sideways
name ways to standardise the collection of earthworms
- time left waiting
- volume of solution
- size of quadrat/ area
- weather conditions (ie. rainfall)
- time of day/ year
name six specialised sampling techniques
- tagging
- auditory monitoring
- photographing
- Trackers
- satellite sensing
- DNA databases
- indirect evidence
name an advantage of using indirect methods for sampling
easy to administer
why use satellite sensing
- for seeing what animals are present and where
-weather monitoring - infrared admitted - shows vegetation density and temperature
- reflected visible light - for creating maps and environmental changes
name advantages of satellite sensing
large amounts of data
can see animal movement and activity
name a disadvantage of satellite sensing
only shows one point at a time
why use DNA databases
to identify individuals, Gene pools, and other genetic relationships ( genetic diversity) eg.eDNA shed in water
what is eDNA
environmental DNA
name the advantages of using DNA databases
- very specific
- DNA can be compared, can track back to find it origin
name disadvantages for using DNA databases
- have to get close up to the animal to extract DNA
- DNA degrades quickly (in warm conditions)
why use tagging
to identify already caught organisms for information on movement and life span eg. rings on bird legs
name an advantage of tagging
clear to tell exactly which animal
name a disadvantage of tiger
- can be irritating to the animal
- could be removed
why use auditory monitoring
species that cannot be seen can be found by the sounds they produce eg. bats
name an advantage of auditory monitoring
information can be gathered with interfering
name a disadvantage of auditory monitoring
the animal is not actually seen
why use photographing
using a range of technologies to monitor the presence and activity of individuals day and night/ behavioural habits eg. camera traps, radio, GPS, acoustic transmitters
name an advantage of photographing
can be set up and left
name a disadvantage of photographing
only sees one moment at a time
why use trackers
trackers place on animals to track movements
name an advantage of trackers
easy to gather data
can be reused
name a disadvantage of tractors
battery can run out
can irritate the animal
what does “used in preference” mean
why better than _______
what is the structure of a 9 marker
3-4:
point - detail/ explanation - examples
eg. technology - data provided - conservation value
what is needed for a 9 marker
B- breath
R- relevance
E- examples
A- accuracy
K- key terms
what is Simpson’s diversity index
(sum of) n(n-1)
what does N mean in Simpson’s diversity index
total number of all species
what does n mean in Simpson’s diversity index
total number of each species
