19 populations in ecosystems Flashcards
what are the two types of quadrats?
point and frame
what is a point quadrat?
a bar with ten holes that a pin can be dropped in
how would you count species with a point quadrat?
count each species that the pin touches
what is a frame quadrat?
square frame with equal sized subdivisions
how would you count species with a frame quadrat?
count each species within the quadrat
what 3 factors should you consider when using quadrats?
- size of quadrat to use
- number of quadrats to record with
- position of each quadrat
do larger species require smaller or larger quadrats?
larger
if a population of species isn’t evenly distributed throughout an area, would you use a smaller or larger quadrat? why?
larger for more representative results
what’s a strength and a weakness of using a large number of quadrats?
strength- more reliable results
weakness- time consuming
how do you choose the position of each quadrat?
random sampling
what is a strength for using random sampling?
avoids bias
how do you take a random sample?
- lay out 2 tape measures at a right angle
- get random coordinates from a computer
- place quadrat at each pair of coordinates and record species within
when would you use systematic sampling over random sampling?
when there is some form of gradual change
eg. starts with sand ends with woodland
how would you take a systematic sample?
- stretch string across ground in a straight line
- lay frame quadrat down along the line and record species
- move quadrat down the line and repeat
when would you use mark release recapture?
when the species are faster moving
