rp 12 Flashcards

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1
Q

Describe how you could investigate the effect of an environmental factor on
the distribution of a species in a habitat (random sampling in two areas)

A
  1. Divide two areas into squares eg. place 2 tape measures at right angles
  2. Generate a pair of coordinates using a random number generator
  3. Place a quadrat here and count frequency
    ○ Standardise this eg. only count it if it is more than half in the quadrat
  4. Repeat a large number of times and calculate a mean per quadrat for both areas
  5. Measure environmental factor in each area eg. take soil moisture readings with a soil moisture meter
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2
Q

why is percentage cover used rather than frequency

A

too difficult too count individual organisms
as they may be too small to count

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3
Q

importance of large sample size

A

minimise effect of anomolies
ensures sample size represents population

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4
Q

Describe how you could decide the number of
quadrats that should be used in order to collect
representative data.

A

● Calculate a running mean
● When enough quadrats, this shows little change
● Enough to carry out a statistical test

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5
Q

Describe how you could investigate the effect of a factor on the distribution
of a species in a habitat (systematic sampling)

A

Place a transect line (tape measure) across an area with an environmental gradient e
2. Place quadrats at regular intervals eg. 1m (until end of transect) and record the number of organisms of
[named species] and [named environmental factor] eg. light intensity using a light meter
3. Repeat in other parallel areas and calculate mean number of plants at each point along the transect

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6
Q

limitations of using systematic sampling to estimate population of a species in a field

A

not suitable unless envi gradient
transects run in one direction but to cover the entire field you’d need to place in multiple directions

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