criteria need to give valid results from quadrats
sample must be TYPICAL of the WHOLE area
the bigger the sample the size the better as smaller ones can be more unusual
why do quadrats need to be placed at random
avoid bias
Why is it necessary to repeat many times
Greater confidence in results
what is quadrat sampling used to do
Data about abundance of species in an area / population size
What is transect sampling used for
Find the DISTRIBUTION of organisms
How can we measure an animal population that moves around
Capture / recapture because if not we may miss species or count more than once
What c1 c2 c3
c1 first captured and then u dye them
c2 secondly captured
c3 the recaptured (the ones from c2 which are dyed)
What c1 c2 c3
c1 first captured and then u dye them
c2 secondly captured
c3 the recaptured (the ones from c2 which are dyed)
Why may the capture/recapture technique be an inaccurate estimate of population size
Migration (into or out of)
We assume there’s been no deaths
Sample size may be too small
