Sampling along a transect

Aim

In this activity, students use transects to collect detailed data about the variety of living things in the study area. A transect is a 10-metre-long straight line across the study area. At one-metre intervals, whatever living thing is under (or above) the tagged mark is recorded. For example, at the start of the transect line, there's grass; at 1 metre, there's soil; at 2 metres, there's a magpie in a wattle tree and so on. Using transects allows you to collect random data about the distribution and abundance of living things in an area.

Print this activity
(MS Word 26kb)

Preparation

You will need:

A 10-metre-long transect marker. To make this, you can use rope or cord or a tape measure. Mark one-metre intervals with knots or pegs or coloured ties.
A reference chart of living things in the area. You prepared this in Step 4 of 'Setting up for success'.
Pencils
Transect data recording sheet (MS Word 38kb).

top of page ^

Process

Step 1 — Set up the transect line for sampling

Working in groups of two or three, students choose a line for sampling in the study area. They extend the 10-metre rope between two points, starting in one kind of ecosystem and finishing in another. The rope can be secured with pegs at each end to minimise movement.

Step 2 — Mark the transect on the map

Each group of students plots the length and direction of their transect line on the map of the study area.

Step 3 — Record living things found at one-metre intervals

At each one-metre interval, observe the living thing(s) immediately under or above the tagged mark. Note this information on the data recording sheet. Collect a sample, take a photograph or do a drawing of each living thing so that you can identify it later.

Step 4 — Compare data

When each group has finished sampling along their transect line, compare the data collected by all the groups. Discuss common data, unique data and the variety in biodiversity.

Biodiversity varies from place to place — this is called 'variation over distance'. Variations between years or seasons are called 'variations over time'. Biodiversity changes over distance and time.

top of page ^

Step 5 — Identify new specimens

Identify any new specimens that were found. Give them a code and then enter them in the reference chart.

Helpful hints

In an area that is sparsely populated, sampling at one-metre intervals might not be best. For example, on a rocky area or a beach, it might be necessary to record all living things along the transect line.

During the class survey, it might be easier to identify living things by a code and take time later to name them if it's necessary. For example, at 0 metres on the transect, the first grass from the reference chart is noted. This can be recorded as G1 (as it is in the reference chart). At 1 metre, a different grass is found. This grass has not been listed in the reference chart and so can be recorded as Ga. The letter 'a' shows that it hasn't been entered in the reference chart yet.

Reporting

Prepare a large map of the site on which to plot the results of all the transects. Use a bar graph to show the numbers of each species found. Comparisons between data from different transects can be discussed and reasons for variations suggested.

When data from earlier surveys is available for comparison, changes over time can be discussed and explanations offered. Is the area biologically stable? Or is it changing over time into a different type of ecosystem?

top of page ^

Reflection

Were students successful in gathering data along the transects?
Where an environmental gradient was included in a transect, was this evident in the data collected?
Did data from the different groups vary appreciably?