Teacher Resource 2: Using Transects

TeacherResource 2

Using transects

This worksheet can be used as a plenary after activity 1 or as a homework.

Ask learners how they might use quadrats to find out how the abundance/distribution of plants changes from one area to another with a gradual change in abiotic factors e.g. from a sunny, dry end of a field towards a shaded, damp woodland or along a sand dune moving away from the sea.

Explain the method tolearners and ask whether this is random or non-random sampling.

Hand out the worksheet.

Lower ability learners may need some support and information on how to draw a kite diagram. Higher ability learners should be able to use the example on the worksheet as a model.

Answers

Two learners wanted to find out how the distribution of plants changed from the seashore to the top of the sand dunes.

Explain how they would carry out a line transect to measure this.

A straight line is marked out from one end of the dune to the other using string/tape.
A tape measure is placed alongside the line.
Quadrats are placed at specified distances along the line e.g. every 2m.
The species of plant are identified using a key/chart.
The percentage cover of each species is counted at each distance along the line.
Repeat measurements are taken.

What abiotic factors that may affect plant growth and therefore distribution do you think would be useful to measure along the transect?

pH, temperature, light intensity, wind speed, humidity, salinity, organic content of sand/soil.

Below is a table of the learner’s results:

Distance from beach (m) / Couch grass / Marram grass / Sea holly / Nettles / Yarrow / Groundsel
0 / – / – / – / – / – / –
5 / 20 / – / – / – / – / –
10 / 38 / 8 / – / – / – / –
15 / 26 / 15 / – / – / – / –
20 / 6 / 32 / 2 / – / – / –
25 / 2 / 24 / 6 / – / – / –
30 / – / 14 / 10 / – / – / –
35 / – / 6 / 12 / 2 / 4 / 6
40 / – / – / 8 / 6 / 7 / 10
45 / – / – / 2 / 8 / 12 / 20
50 / – / – / – / 10 / 15 / 24

Draw kite diagrams on the graph paper below for each plant. Couch grass has been done for you.

Graphs plotted correctly, labelled and drawn to the same scale as the graph for couch grass.

Use your diagrams to answer the questions:

Which plant is the most tolerant to salty conditions? Explain your answer.

Couch grass – it is the one that grows closest to the beach i.e. the sea.

Rabbits and other animals graze on one area of the sand dune, excreting waste on to the ground. Which plants grow in this area? Explain your answer.

Nettles, yarrow and groundsel – the waste puts nutrients into the ground (and increases the organic matter in the soil) and these three plants must need this as they don’t grow on the less nutrient-rich sand.

At which distance from the beach is the sand dune at its most biodiverse? Explain your answer.

35m – it is the only distance where five different species of plant grow.

At which distance from the beach is the sand dune at its least biodiverse?

0-5m – at 0m no plants grow and at 5m only one species of plant is found.