Describe how you would determine the mean percentage cover for beach grass on a sand dune.

The scientists concluded that the results shown in Figure 5 were due to succession taking place.

Use Figure 5 to explain why the scientists reached this conclusion.

The scientists also investigated how the proportion of sunlight reaching the ground changed during succession. Some of the results the scientists obtained are shown in Figure 6.

Use Figure 5 to explain the results in Figure 6.

Using evidence from Figure 6, what can you conclude about the net primary productivity (NPP) in the sand dunes that are older than 1000 years?

Explain your answer.