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