Investigating seed dispersal

In a nutshell

Seed dispersal is very important to reduce competition between new plants. The dispersal distance can be easily measured for different fruits and the impact of the wind can be measured.

Investigating seed dispersal

This experiment tests the seed dispersal distance of different fruits.

Procedure

1.	Find fruit containing seeds. Example Sycamore or conkers.
2.	Choose a height to drop the fruit from. Example One metre above the ground.
3.	One at a time, drop the fruit from your chosen height.
4.	Use a ruler or tape measure to measure how far the seeds have been dispersed on the ground.
5.	Repeat this procedure three times for each fruit.
6.	Calculate the average distance each seed disperses after being dropped.

Factoring in the wind

Wind can impact the distance that a seed is dispersed. If the fruit is light then it can be carried in the wind and the seeds will be dispersed further away from the parent plant. A similar experiment can be carried out to investigate how wind affects seed dispersal.

Procedure

1.	Set up an electric fan a set distance (like $30\ cm$ ) away from the person dropping the fruit.
2.	Choose a speed setting on the fan (this must be the same for each repeat and each fruit) and turn the fan on.
3.	Drop the fruit from a set distance as before.
4.	Measure the dispersal distance using the same method as before.
5.	Repeat this procedure three times for each fruit.
6.	Calculate the average distance each seed disperses after being dropped.

The wind should make the lighter fruits, like the sycamore, travel further. Heavier fruits, like conkers, may not be affected by the wind.

Fair test

To be able to make fair comparisons between the dispersal distances of all the fruits that are being tested, everything must be the same except the thing you are testing. This is called controlling the variables.

This means that the person dropping the fruit must be the same each time. The height the fruit is dropped from should also be the same and you must always drop the fruit in the same location as things like open windows or uneven surfaces may affect the distance the fruit travels.

Science; Plants; KS3 Year 7; Investigating seed dispersal

Science; Plants; KS3 Year 7; Investigating seed dispersal