Question 1
Paper 2Hard16 marksEcologists surveyed the same twelve 1 ha woodland plots in 2012, 2018 and 2024. Expert teams used the same method, visited at the same time of year and spent the same amount of time surveying each plot. The table shows the numbers of individuals recorded for six native bird species. A zero indicates that no individuals of that species were recorded.
| Species | 2012 | 2018 | 2024 |
|---|---|---|---|
| A | 40 | 50 | 70 |
| B | 30 | 24 | 12 |
| C | 20 | 14 | 4 |
| D | 10 | 7 | 2 |
| E | 8 | 5 | 0 |
| F | 2 | 0 | 0 |
A citizen-science portal also collected observations in the surrounding landscape. A record is one submitted sighting, not a count of unique species. The portal did not use fixed observer-hours or fixed locations, and sightings were not independently checked.
| Year | Records submitted | Contributors | Habitat types sampled |
|---|---|---|---|
| 2012 | 1 200 | 80 | 3 |
| 2024 | 5 100 | 600 | 9 |
Other estimates for the same landscape were:
| Measure | 2012 | 2024 |
|---|---|---|
| Human population | 42 000 | 59 000 |
| Native woodland remaining / ha | 1 200 | 780 |
| Woodland converted to agriculture or settlement since 2012 / ha | 0 | 420 |
| Plots occupied by an invasive alien plant / 12 | 1 | 7 |
Calculate the percentage change in recorded bird species richness between 2012 and 2024.
Describe how species richness and evenness changed in the bird survey between 2012 and 2024.
State one benefit of citizen-science observations and explain why the increase in portal records alone does not establish an increase in biodiversity.
A conservation group concludes that biodiversity in this landscape is recovering and that any decline in the bird survey was caused solely by human population growth. Evaluate whether the data support these conclusions.