Sampling and studying ecosystems

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Describe a quadrat
1m square and string across every 10cm, separating it into 100 squares.
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What can we record with a quadrat?
Either the distribution or abundance of each species.
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What is distribution?
The presence or absence of each species.
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What is abundance?
Estimating or counting the number of individuals.
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When it is difficult to count individuals, what do ecologists tend to estimate?
Estimate percentage cover.
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What will improve the estimate?
Using a point frame.
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How is a point frame used?
Each needle should be lowered downwards and species recorded that the tip touches.
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How can we avoid biasing the sample?
Randomly position the quadrats across the habitat using random numbers to plot coordinates. Taking samples at regular distances.
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How do ecologists work out how many quadrats are needed?
Carry out pilot study with random samples and plot cumulative frequency against quadrat number. Where curve levels off.
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How do you work out what size the quadrats should be?
Plot quadrat area on x axis against no. of species you find in each one. Read where curve levels off.
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What is the equation used to estimate the population size of a species?
Mean no. of individual of species in each quadrat/fraction of total habitat area covered by quadrat.
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How is a transect used?
Line taken across a habitat/stretched out tape measure. Take samples at regular intervals along tape.
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How is a line transect used?
Taken at regulation intervals, make a note of which species are touching the tape.
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How is a belt transect used?
At regular intervals, place quadrat next to the line (interrupted belt) and study each or move the quadrat along the line (continuous belt transect).
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Other cards in this set

Card 2

Front

What can we record with a quadrat?

Back

Either the distribution or abundance of each species.

Card 3

Front

What is distribution?

Back

Preview of the front of card 3

Card 4

Front

What is abundance?

Back

Preview of the front of card 4

Card 5

Front

When it is difficult to count individuals, what do ecologists tend to estimate?

Back

Preview of the front of card 5
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