4.2.1 c sampling techniques Flashcards
what sampling techniques can be used to collect living animals?
a pooter
sweep nets
pitfall traps
tree beating
kick sampling
how is a pooter used?
used to catch small insects
suck on a mouthpiece
insects drawn into holding chamber via the inlet tube
a filter before the mouthpiece stops the insect from being sucked into the mouth
when are sweep nets used?
to catch insects in areas of long grass
how are pitfall traps used?
to catch small, crawling invertebrates
a hole is dug into the ground where the insect falls into
must be deep enough that they can’t climb out of it and covered with a roof-structured propped above it so it can’t fill with rainwater
traps are normally left overnight
what is tree beating?
used to take samples of the invertebrates living in a tree or bush
a large white cloth is stretched under the tree
tree is shaken or beaten to dislodge the invertebrates
they will fall onto the sheet where they can be collected
what is kick sampling?
used to study organisms that live in a river
river bank and bed is kicked for a period of time to disturb the substrate
a net is held just downstream for a set period of time to capture the organisms released into the flowing water
how are plants sampled?
using different types of quadrats
what else can be sampled by quadrats?
slow-moving animals like limpets, barnacles, mussels and sea anemones
what are the two main types of quadrats?
point quadrat
frame quadrat
what are point quadrats?
consist of a frame containing a horizontal bar
at set intervals along the bar, long pins can be pushed through the bar to reach the ground
each species of plant the pin touches is recorded
what are frame quadrats?
consist of a square frame divided into a grid of equal sections
type and number of species within each section of the quadrat is recorded
what sampling technique should be used to collect the most valid representative sample of an area?
random sampling technique
how do you measure species richness?
a combination of techniques should be used to try to identify all the species present in a habitat
a list of all species identified should be compiled
the total number of of species can be calculated
identification keys are used to help scientists accurately identify organisms
how do you measure species evenness?
frame quadrats
what are frame quadrats used for?
sample a population of plants living in a habitat
what are the three ways of using a frame quadrat ?
density
frequency
percentage cover
how is density measured in a frame quadrat?
count number of individual large plants in a 1m by 1m square quadrat
will give you density per square metre
absolute measure not an estimate
how is frequency measured in a frame quadrat?
using the small grids within the quadrat, count the number of squares the species is present in
work out percentage of squares the species is present in
how is percentage cover measured in a frame quadrat?
used for speed
useful when a particular species is abundant or difficult to count
estimate by eye of the area within a quadrat that a particular species covers
how do you estimate a animal population size?
capture-mark-release-recapture
how does the capture-mark-release-recapture technique work?
capturing as many individuals of a species as possible
organisms are marked and released back into the community
time is allowed for the organisms to redistribute themselves throughout the habitat before another sample of animals is collected
compare the number of marked animals to the number of unmarked animals in the second sample so scientists can estimate population size
how can the species evenness of animals be calculated?
by comparing the total number of each organism present in an area
what are abiotic factors?
non-living conditions in a habitat
why do scientists measure the abiotic factors?
to enable them to draw conclusions about the organisms present and the conditions they need for survival
scientists normally measure them at each sampling point
how can abiotic factors be measured?
range of sensors
why are sensors advantageous for taking readings of abiotic factors?
rapid changes can be detected
human error in taken a reading is reduced
high degree of precision can often be achieved
data can be stored and tracked on a. computer
