Distribution of organisms pt 2

Transects are used to study the distribution of organisms along a line.
1. 1) Mark out a line in the area you want to study, using a tape measure.
2. 2) Then collect data along the line, e.g how many daisies are along the line.
  1. You can do this by just counting all the organisms that you are interested in that touch the line.
  2. Or you can collect data by using quadrants. These can be placed next to each other along the line or at intervals e.g every 2m.
When collecting environmental data you need to think about reliability and validity.
1. Reliability
  1. Quadrants and transects are pretty good tools for finding out how an organism is distributed.
  2. You have to work hard to make sure your results are reliable - which means making sure they are repeatable and reproducible.
  3. To make your results more reliable you need to:
    1. Take a large sample area e.g using as many quadrants and transects as possible. Bigger samples are more representative of the whole population.
    2. Use random sample e.g randomly put down or mark out your quadrant or transect.
2. Validity
  1. For your results to be valid they need to be reliable and answer the original question.
  2. To answer the original question, you must control all the variables.
  3. The question you want to answer whether a difference in distribution between two samples areas is due to a difference in one environmental factor.
  4. If you've controlled all the other variables that could be affecting the distribution.
    1. You'll know whether a difference in distribution is caused by the environmental factor ore not.
  5. If you don't control the other variables you wont know whether any correlation you've found is because of the following things:
    1. Chance, the environmental factor or a different variable.

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Distribution of organisms pt 2

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	Created by jessica-gollop about 11 years ago