Plant Sampling Methods (2.3.1)

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Why do we take samples?
To estimate the total numbers present in an area.
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Why would you sample an area randomly?
To avoid bias.
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How do you sample randomly?
Use a random number table to generate coordinates of areas to take samples from, as this is down to chance.
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How would you sample systematically?
Lay out string in a straight line and take samples along the line. This is called a transect.
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Give two ways in which a transect can be used.
You can record every plant touching the string, which would give a descriptive account of species present. Also, you could lay quuadtrats at fixed distances along the string and sample within these (interrupted belt transect).
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How many samples should be taken in a small field?
20 samples would be sufficient.
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Why should more samples be taken?
The more samples taken, the more reliable the results will be.
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What is a disadvantage of random sampling?
You can miss rarer species that occur infrequently in an area.
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What is a quadrat?
A square frame that marks off an area of ground, in which you can make a survey of which species are present.
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Why is it not necessary to use the biggest quadrat possible?
There comes a point when using a bigger quadrat makes no difference to the number of species found.
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What could be measured in each quadrat?
Species richness, species frequency, species density and percentage cover.
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What is species richness?
The number of different species in the quadrat.
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What is species frequency?
How many of a species is found in each quadrat.
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What is species density?
The number of each species in each quadrat.
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/What is percentage cover?
You use a frame holding a number of long needles. You lower the frame into the quadrat and record any plant touching the needles.
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Other cards in this set

Card 2

Front

Why would you sample an area randomly?

Back

To avoid bias.

Card 3

Front

How do you sample randomly?

Back

Preview of the front of card 3

Card 4

Front

How would you sample systematically?

Back

Preview of the front of card 4

Card 5

Front

Give two ways in which a transect can be used.

Back

Preview of the front of card 5
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