Required practical
Measure the population size of a common species in a habitat
Greg Foot describes how to carry out a field investigation into distribution and abundance of organisms in an ecosystem
Aim
To measure the species richness on the school field in areas in which the grass is regularly and irregularly cut.
Method
- Choose an area on the school field where the grass is often cut. Map the area and then lay a numbered grid over the map.
- Use Occurring without a pattern. Unpredictable. In statistics where each item has an equal probability of being selected. numbers where to place your first A square frame of known area used for sampling the abundance and distribution of slow or non-moving organisms.. You can use a computer generated random number table to do this.
- Count the number of different plant A type of organism that is the basic unit of classification. Individuals of different species are not able to interbreed successfully. within this quadrat (the species richness).
- Return to your starting position and repeat steps two and three a further 14 times using different random numbers.
- Repeat steps one to four for a part of the school field which the grass is infrequently cut.
- Compare your results by calculating a The average. for each location.
Results
| Quadrat number | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
| Number of plant species per quadrat (on cut area of the school field) | 1 | 2 | 1 | 2 | 3 | 1 | 3 | 1 | 1 | 1 | 2 | 3 | 2 | 1 | 1 |
| Number of plant species per quadrat (on uncut area of the school field) | 3 | 2 | 4 | 6 | 1 | 1 | 1 | 4 | 5 | 3 | 6 | 4 | 5 | 3 | 4 |
| Quadrat number |
|---|
| 1 |
| 2 |
| 3 |
| 4 |
| 5 |
| 6 |
| 7 |
| 8 |
| 9 |
| 10 |
| 11 |
| 12 |
| 13 |
| 14 |
| 15 |
| Number of plant species per quadrat (on cut area of the school field) |
|---|
| 1 |
| 2 |
| 1 |
| 2 |
| 3 |
| 1 |
| 3 |
| 1 |
| 1 |
| 1 |
| 2 |
| 3 |
| 2 |
| 1 |
| 1 |
| Number of plant species per quadrat (on uncut area of the school field) |
|---|
| 3 |
| 2 |
| 4 |
| 6 |
| 1 |
| 1 |
| 1 |
| 4 |
| 5 |
| 3 |
| 6 |
| 4 |
| 5 |
| 3 |
| 4 |
Question
What are the totals and means for the two different locations?
A total of 25 and a mean of 1.7 on cut school field and a total of 52 and a mean of 3.5 on uncut school fields.
Conclusions
Question
What conclusions can you draw here? [4 marks]
The mean of the number of plant species in the cut school field is lower than on the uncut school field (1 mark). There is a mean of 1.7 different species per quadrat on the cut grass (1 mark). The number of plant species per quadrat on the uncut field is over twice this at 3.5 (1 mark). Therefore, there is greater species richness on the school field in uncut areas (1 mark).
Question
What limitations might there be in drawing these conclusions?
The two students only placed 15 quadrats. Completing more would allow them to be more confident in their conclusions.
