3.14 Investigating Abundance & Distribution

Question 1

What are the two main sampling methods?

Answer 1

1) Quadrats - to measure abundance
2) Transects - to measure how distribution changes

Question 2

How can you investigate how the distribution of an organism gradually changes across an area?

Answer 2

Using lines called transects

Question 3

What is a belt transect?

Answer 3

Sampling along the length of a transect using a quadratic.

Question 4

Describe in 4 steps how to do a belt transect

Answer 4

1) Mark out a line in the area you want to study using a tape measure.
2) Place a quadrat at the start of the line and count and record the organisms you find in the quadrat.
3) Then, instead of picking a second sampling site at random, you take samples by moving your quadrat along the line, e.g. placing the quadrat at intervals of every 2m. You could even take samples along the entire length of your transect by placing your quadrats right next to each other. This might take ages if you have a long transect though.
4) Repeat your transect at least twice more at different places within the area you want to study.

Question 5

What are transects used for?

Answer 5

Transects are used to observe and record changes in species distribution across an area.

Question 6

Explain what sampling means and why it is often used.

Answer 6

Sampling means only counting a subset of the organisms in a habitat. This is done because it would be impossible, or very time consuming, to count all the organisms.