10 - Effect of one abiotic factor on species distribution & morphology

What equipment is needed for this practical?

• Quadrat

• 20 metre tape measure

What is the method for this practical (light intensity) ?

1. Choose an area with clear gradient of light intensity

2. Lay 20m tape measure from open area to shaded area

3. Look along transect & pick plant species that clearly changes in number along the line

4. Begin at one end of transect & lay quadrat next to 0m mark of the tape 

5. Measure light intensity at ground level

6. Record abundance of chosen species at this point by counting number present 

7. Move quadrat 2m along tape & repeat steps 5 & 6

8. Continue until you have 10 measurements along transect

9. Create two more transect running from the openly lit to the shaded area & repeat steps 4 to 8 to obtain repeats (or class data can be shared)

What are some considerations to keep in mind?

• Take readings close together in time to ensure light intensity doesn’t vary much

• Using an interrupted transect is quicker & can be used to measure a greater distance

• Instead of recording abundance via counting number of species, we can estimate percentage cover (less accurate as it’s an estimation)

What things should be included in the risk assessment?

• Be cautious when handling quadrats & ensure they’re not thrown

• Cover cuts & wash hands after fieldwork to prevent risk of infection from plants/soil that could have been contaminated with animal faeces

• Use sunscreen if working in an area with high UV for long periods of time

• Don’t enter water & ensure you can be seen by others at all times

• Wear gloves if working with nettles 

• Possibility of allergic reaction from pollen, so inform teachers if you fell unwell

What is the conclusion from this practical?

There may be a relationship between light intensity & chosen plant species, but it doesn’t mean light is the cause - other factors (e.g. competition, soil moisture) can also influence distribution