Table 1 shows plant species recorded at one site, on one island, in 1975.

Calculate the index of diversity for this site using the formula:

d = N(N−1) / Σn(n−1)

d = ______________

Outline a method the ecologists could have used to determine the plant species richness at one site.

Some of the ecologists' results are shown in Table 2. They carried out a statistical test to find out whether any differences between the 1975 and 2010 means were significant. The values for P that they obtained are also shown in Table 2.

Do these data show that there were any significant changes in the grassland communities on these islands? Give reasons for your answer.